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Energy/Electricity Storage and Use/Grid Connection => Off-Grid, Batteries & Inverters => Topic started by: andrewellis on September 17, 2018, 09:29:12 PM



Title: Are batteries worth it, does this calculation work?
Post by: andrewellis on September 17, 2018, 09:29:12 PM
I am trying to determine if batteries are worth it.  I should probably wait a year before getting some, but the vat saving could make it worth while doing now.

I am looking at the  ME3000SP range with pylon batteries which seem quite good value for money.  Key points : 6000 cycles, 80% DOD, 94.5% charge efficiency. 94% discharge efficiency.
Assumptions: linear discharge to 70% at 6000 cycles = average of 85% use
Current price of electricity .15.  I'll use that as most of the use is in the early stages
9.6kwh battery
So is this calculation too basic?  

Power per cycle = 9.6 *.8 * .85 *.945 *.94 =5.79kwh
power saved over life time = 6000 * power per cycle
cost  = .15 * 6000 * 5.79 = £5200  This sounds like a god return on investment.

However 6000 cycles is over 16 years assuming 1 per day. I haven’t had a single laptop battery last more than about 4 years before it has no more than 5 minutes charge held.  Does age alone have a big effect on these batteries so I shouldn’t expect more than about 10 years life?  If that is the case I’d not be able to use the 6000 charges before the battery dies and certainly won’t come near paying back.

I’m just curious if anyone has had batteries for a while (>5 years) and what charge the are holding compared to when they bought them. Thanks.


Title: Re: Are batteries worth it, does this calculation work?
Post by: RIT on September 17, 2018, 10:57:41 PM
I am trying to determine if batteries are worth it.  I should probably wait a year before getting some, but the vat saving could make it worth while doing now.

I am looking at the  ME3000SP range with pylon batteries which seem quite good value for money.  Key points : 6000 cycles, 80% DOD, 94.5% charge efficiency. 94% discharge efficiency.
Assumptions: linear discharge to 70% at 6000 cycles = average of 85% use
Current price of electricity .15.  I'll use that as most of the use is in the early stages
9.6kwh battery
So is this calculation too basic?  

Power per cycle = 9.6 *.8 * .85 *.945 *.94 =5.79kwh
power saved over life time = 6000 * power per cycle
cost  = .15 * 6000 * 5.79 = £5200  This sounds like a god return on investment.

However 6000 cycles is over 16 years assuming 1 per day. I haven’t had a single laptop battery last more than about 4 years before it has no more than 5 minutes charge held.  Does age alone have a big effect on these batteries so I shouldn’t expect more than about 10 years life?  If that is the case I’d not be able to use the 6000 charges before the battery dies and certainly won’t come near paying back.

I’m just curious if anyone has had batteries for a while (>5 years) and what charge the are holding compared to when they bought them. Thanks.


The issue regarding battery life is that of the battery management system in place. For laptops and mobiles, there is sod-all to very little, while for large battery packs used for storage and cars there is a lot of focus on the battery management. This is how you can see reports of even the 24kWh Nissan Leaf hitting 100,000 miles when used as a taxi and still usable, with little-reported drop in cell capacity.

When trying to value a battery I start the calculation from a different point. Overall equipment costs are still dropping and this should continue. A case in point is the pylon battery as next year we should see the larger 3.4kWh unit replace the current 2.4kWh unit. So I look at the possible savings from deploying a system for say the next year and then compare it against the likely drop in the cost of the system over the year.

So far the installation of a battery system has never made much sense as the possible value of energy saving for my situation have never been higher than the year on year fall in equipment costs. At the same time, the funds stay doing something else :)

In terms of your calculations, you seem to be basing them on the ability of your PV system to fully recharge the batteries every day and that you then gain full value by discharging the batteries every day. You will have to look at your generation and usage in more detail I think. It's more common for the PV to provide excess energy during Spring and Summer, while you do not draw much energy from the batteries. At other times you are likely to draw more but store less.


Title: Re: Are batteries worth it, does this calculation work?
Post by: Scruff on September 18, 2018, 02:15:33 AM
You haven't factored the battery charge efficiency (only the charger/inverter efficiency).
The battery mean charging efficiency (diminishing returns with age).
The simple fact that manufacturer quoted efficiencies are usually contrived and often ≥10% inflated on what you can expect in real world normal operating conditions.
Ambient temperature deratings. Battery self consumption (li-ion smanchy packs often have preheaters to stop them igniting in low ambient temperature conditions)
Installation losses (AKA: installer get home in time for dinner legacy losses)
Power factor considered reduced effective capacity.
Replacement inverter costs (only Studers live longer than 10 years)
Unfounded lifecycle claims.

Age does not have a big effect on batteries the potential for neglect and abuse over lifetime is the more pertinent issue.

Are batteries worth it?
I think so. I don't pay a lot for them though and none of mine are proprietary.

Ain't no data like empirical data.


Title: Re: Are batteries worth it, does this calculation work?
Post by: splyn on September 18, 2018, 03:03:11 AM

I am looking at the  ME3000SP range with pylon batteries which seem quite good value for money.  Key points : 6000 cycles, 80% DOD, 94.5% charge efficiency. 94% discharge efficiency.

Its easy to claim xxx thousand cycles but LiFePo4 batteries haven't been round long enough for any reliable data on lifespan to have become available. Accelerated life testing in relatively ideal conditions in a manufacturer's test environment is one thing - whereas data from customers using them in real world, variable, conditions over long periods is almost none existent (unless anyone here knows different).

Personally I'd be very wary of any claims beyond 2000 cycles which used to be typical specs for LFP cells until one manufacturer (Winston?) starting claiming 7000 cycles. That claim, along with Pylon's 6000 cycles may well be legitimate but it will take a long time before it is verified by independant parties.

Quote
Assumptions: linear discharge to 70% at 6000 cycles = average of 85% use
Current price of electricity .15.  I'll use that as most of the use is in the early stages
9.6kwh battery
So is this calculation too basic?  

Power per cycle = 9.6 *.8 * .85 *.945 *.94 =5.79kwh
power saved over life time = 6000 * power per cycle
cost  = .15 * 6000 * 5.79 = £5200  This sounds like a god return on investment.

I assume your electricity is coming from PV. As RIT said, to be able to generate, and use 5.79kWh in excess of your usage during the generation period, daily throughout the year seems to be surprising if not impossible - in winter a 6kW PV system might produce that much, on average, and given the average 10kWh/fday UK household consumption would likely be easily consumed. But in summer it would be producing far more - from perhaps 8am to 8pm or later - so would you be likely to consume nearly 6kWh after 8pm?

And averages, being what they are, means there will be many periods of a few days when you get very little generation and many when you get far more than you can use. I'd be surprised if you could use this much stored capacity every day which would have a big impact on the economics if you don't

Quote
However 6000 cycles is over 16 years assuming 1 per day. I haven’t had a single laptop battery last more than about 4 years before it has no more than 5 minutes charge held.  Does age alone have a big effect on these batteries so I shouldn’t expect more than about 10 years life?  If that is the case I’d not be able to use the 6000 charges before the battery dies and certainly won’t come near paying back.

I think you are right to be wary. In the Pylon datasheet I looked at it stated 'Design life 10 years'. I have no idea what that means precisely, but to hope for 16 years life in addition to 6000 80% cycles seems to be a truely heroic assumption.

I suggest you have a look at this site (especially the 6 month reports) which is an Australian company testing several home storage systems:

http://batterytestcentre.com.au/ (http://batterytestcentre.com.au/)

They are testing a variety of battery types including Li-ion, LFP, Lead acid etc. They produce reports every 6 months and so far it's not very encouraging - they have had a lot of 'issues', including BMS faults, faulty cells and a manufacturer going bankrupt. It is important to note that the tests are being conducted in Australian temperature conditions which are quite high in summer compared to UK conditions which will  adversely impact lifespan. Also the Tesla Powerwall 1 system, which is performing badly, is being driven harder than the other systems so is not directly comparable. They are testing the Pylontech US2000B as part of their second tranche and although it is rather early, it looks to be performing well wrt. capacity fade (see the 4th report) - so perhaps it will meet the manufacturesers claims.

Despite the caveats, the thing I would takeaway from this study is that these systems are still in their infancy and I personally wouldn't put much trust in any of the specifications at this stage. The warranties may look good but some of the smaller companies might not be around in 5 or ten years time; claiming on the warranties may be almost impossible, except in cases of relatively clear cut early failures, given the typically very long list of conditions in the warranty small print - most of which will be virtualy impossible to prove either way.

Batteries are essential for off-gridders but my opinion is they are a mug's game for anyone else who isn't in it principally to enjoy the challenge and experimentation. Those who are trying to game the system by taking our FIT money for generating power and getting paid for deemed exports that they aren't delivering, deserve everything they get... IMHO.


Title: Re: Are batteries worth it, does this calculation work?
Post by: djs63 on September 18, 2018, 09:13:20 AM
Good detailed topic, thank you to the contributors, it is helping me considerably.

Some one on here called the grid “a battery’ and at the moment, that is how I treat it.  As an extremely simplified example, if I use 5 KWh per day from the grid it costs around 75 pence (UK) and if I’m lucky I can take 3 pence per KWh off that for fITs export.  Thus 365 days at 75 pence, call it £280 per year for the use of a battery, ie the grid.

In 10 years equals still only £2800 though the price of electricity and of battery packs will be different, much less than a big battery pack currently.

But is diesn’t help the planet as much as not using the grid at all.

Do Li based batteries require “looking after”? Should you regulate the environment temperature, clean the terminals...?


Title: Re: Are batteries worth it, does this calculation work?
Post by: skyewright on September 18, 2018, 09:46:42 AM
I assume your electricity is coming from PV. As RIT said, to be able to generate, and use 5.79kWh in excess of your usage during the generation period, daily throughout the year seems to be surprising if not impossible
Another factor is charge rate, i.e. the maximum rate at which the batteries can accept charge (sorry if it's already been mentioned & I didn't spot it). Even if you have 5.79kWh of excess you can't necessarily store it all if at times the excess PV is being generated at a rate that is greater than the batteries can accept; in that situation some of your 'excess' will still be exported.


Title: Re: Are batteries worth it, does this calculation work?
Post by: andrewellis on September 18, 2018, 10:25:29 AM
Thanks chaps for the detailed replies. It makes very interesting reading and has certainly helped with my decision making.

RIT - thanks, I didn’t realise the importance of the BMS. I didn't realise laptop batteries had no management.  With regard the calculations, I was thinking hypothetically if I was able to make use of all 6000 cycles independent of the time taken.  That’s where the concern about age comes in.  Will I achieve 6000 cycles at a rate of say 180 a year?  I am on economy 10 already so could time shift but the return on that wouldn’t cover the cost of the batteries.  So it doesn't seem to make sense to waste charge cycles on that.

Scruff -  So it is even more pessimistic for the electricity round trip than I realised.  I am running a GSHP so the power factor would be an issue.  I am curious, do you build your own battery packs? I would love to go down the line of retrieving the battery from my Leaf at EOL but knowing what a clumsy fella I am I don’t think I would survive long enough to tell you about it afterwards.


Splyn - We do have a very high usage which would easily allow for a cycle or two a day during the summer months.  We have 40kwh most days during the summer so we have the ability to absorb the solar pv usage. If I could ultimately use all 6000 cycles it might be worth it.  I remember there was a lot of fear about the life span of electric cars.  A well managed car battery seems to do quite well these days. I hadn't noticed the site you linked to. Thanks for the link. I feel that on some level, taking on renewables as a small invididual whilst noble is a bit of a gamble.  Reading those reports seems to back this up.  The testing site got decent backup support with battery issues as the companies involved want to show the product in the best light.  What happens to the general public who don't monitor every stat on the batteries. As an aside, wind turbines when working are fantastic, but get a turbine which is misbalanced out of the factory can lead to large repeat repair bills.  They seem to be suffering from the same problem of companies disappearing rapidly leaving a lot of farmers locally with very expensive stationary decorations.  Without a field of turbines averaging out the problems you are playing a 1 in 1000’s lottery of sending your cash down the toilet.  

The whole FIT argument / gaming the system is an interesting one which is probably for a different thread.  The government wanted to encourage the uptake of all these technologies which seem to come with a reasonable risk of equipment failure.  Without direct support for replacement of the equipment, the FIT gives some cover for the failures.  Without it, from a monetary point of view there is no point in installing the renewables at small scale.  On another hand if it is such an inefficient process of funding renewables why did we bother doing it.

I am approaching this from many sides;the geek side of things, slightly altruistic, financial gains (effectively locking in to current electricity rates).  However 4.8Kw of solar panels only produce about a 5th of what I use in the year.  Batteries would allow me to time shift the solar production during the summer months in to my GSHP, car charging, dishwasher etc.  However I suspect from replies you have solidified my view in that it probably isn't worth it financially this year.  I have quite a high base load of 900w so I'll be better off spending a few £100 on the solar edge car charger and diverting straight into the car when it is parked on the drive. I shall give it a year and reassess based on my usage rather than diving headlong into purchasing a battery set up now.




Title: Re: Are batteries worth it, does this calculation work?
Post by: Scruff on September 18, 2018, 11:22:44 AM
I build my own batteries. I get the terminals of one battery/cell usually it's about 20kg thereabouts per, I find this easier and more reliable than 90 bazillion teeny ones. I attach it to one beside it lather rinse repeat until I have the desired capacity. I put a master fuse on it and I tail it to a bus bar.

I don't have any li-ion BMS problems because I use lead acid. I've never found them lacking.
I notice most of the proponents of li-ion rather read marketing than data.

I agree with Splyn, batteries as a financial investment for grid-tied is a mug's game.
Mechanical grid-level storage is a no-brainer.

PS. I think you are confusing pessimism with pragmatism.

A lottov people like to call me cynical too. I'm not. I simply benchmark products against their own claims (with certified or traceable calibrated independent test gear) and more often than not find them lacking. Studer and MorningStar are the only manufacturers in this business I have found that live up to self-assured expectations. I could give you a much longer list of those that don't and it'd be fact not defamatory but life's too short.



Title: Re: Are batteries worth it, does this calculation work?
Post by: andrewellis on September 18, 2018, 01:26:39 PM
Crikey, 20kg.  Where do you get them from?  I was looking at the fork lift based ones earlier.

I am on the cautious side in life, would I be right in saying that I should build a small shed to house them with lots of holes in the roof?  I remember, in the Navy, the battery charging bay was usually above deck in its own shed.


Title: Re: Are batteries worth it, does this calculation work?
Post by: biff on September 18, 2018, 02:06:40 PM
This is indeed an interesting thread,
                         "Is it worth it"
     The Answer is both YES and NO!  or depending where you live,,either in the town or the country, Or again, how much you value your independence.
                    Biff


Title: Re: Are batteries worth it, does this calculation work?
Post by: dan_b on September 18, 2018, 03:39:39 PM
As someone who is a "soft-gridder" - as in I have solar PV and a grid-connected battery - for almost 2 years now, I can say that the question of whether it's worth is depends on what you consider the priority.

Firstly - this a clean energy/renewables forum, so you would hope a major priority for anyone here is reducing/ eliminating their reliance on fossil-fuel power.   Therefore on that basis alone, if you have some spare cash and want to spend it on reducing your import of grid power, then that's definitely "worth it."  There's a mantra on here which is "insulate insulate insulate" as far as reducing your heating energy consumption is concerned - but rarely does anyone go "oh don't bother with spending money on insulation you'll never make a return on your spend".   It's also a different equation if you're fully off-gridding as you are doing it by necessity, but each to their own. We can't all do that, but we can all try and make a difference.

Secondly - what else would you do with the money if you didn't spend it on a battery system? Is it just burning a hole in your trousers, do you need it for a "rainy day", or are you happy to splash some cash on what is basically an experiment in early adoption, but one in which you get to learn, and reduce your grid import at the same time?

Thirdly - how prepared are you to tinker?  If renewables/ batteries/ lowering your electricity/carbon consumption is something you're basically rather interested in and want to get involved with, then buying/building a battery is a good way to learn something - for your own benefit, but ultimately for others' benefit too.  But it does take up time!

Now on the actual finance-side...
To get the 15% VAT saving for a grid-tied battery, you're supposed to have to install it at the same time as some Solar PV.
To maximise the battery efficacy, get yourself on an Economy 7 tariff as well, so that in the dark months, you can get some charge in it overnight at the lower rate and get some useful work out of it as a result.
If you can build it yourself it'll be cheaper, but you won't have the warranty support. 
Some battery manufacturers and also some DNOs/ utility suppliers are experimenting with supporting batteries via a remote control tariff as well - ie they pay you to use your battery capacity as a local voltage control unit.  See if they are available in your area.

If it helps, I got a 4kWh PowerVault fitted in Dec 2016. In the first year it discharged 864kWh - so that's power I generated and avoided importing.
This year, I added E7 charging and have so far in the first 9 months discharged  1150kWh - which obviously includes E7 tariff import, but again shows the battery is working and saving me from buying electricity from the grid at the full rate.   I've probably "saved" £200 now in avoided import/tariff shifting, so it's not a total game-changing amount, but my dual fuel bill is now below £60/month for a household of 4 people.

Shop around and see what you can find.


Title: Re: Are batteries worth it, does this calculation work?
Post by: biff on September 18, 2018, 05:29:50 PM
Very good post Dan b,
                        And very true,
 You put it a lot better than i could. I wrote a load of drivel about being off grid and even if i was on grid, i would have a large bank and a 5kw UPS between me and the CU.
  However, I scrapped it because not everyone wants to "Tinker" and "Tweak" like me. Not everybody wants complete control over their electricity generating like me.
 Having a battery like in your situation is obviously the way forward for everyone and will also lessen the need for heavier infrastructure , lines ,transformers, etc.
 The Aussies lead the way in this respect with whole communities connected through their home Batteries , kept topped up by PV. It,s a worker. A giant step in the right direction.
                                               Biff
                         


Title: Re: Are batteries worth it, does this calculation work?
Post by: brackwell on September 18, 2018, 07:21:44 PM
Like others I have been thinking about this issue and concluded that stand alone batts do not work financially, but when the advent of TOU (Time of use) tariffs are imposed and then we have EVs and V2G tech. i wonder if there may not be a better way. Most of the PVs have diverters for the DHW but now we can have them for the EV and i believe that these two items and may be other demand controlled items can absorb  more than stand alone batts but in the case of the EV i feel i am saving expensive polluting FF.  I know for some people this may entail more than one EV ie an expensive one and a cheap one say £5K  but the cheap one will be cheaper than a powerwall etc and have twice the capacity.  Anyway just my thoughts.

Ken


Title: Re: Are batteries worth it, does this calculation work?
Post by: Scruff on September 18, 2018, 08:29:34 PM
Crikey, 20kg.  Where do you get them from?  I was looking at the fork lift based ones earlier.

Flooded golf carts for light duty. Flooded OPzS if yer serious. Flooded forklifts if you want cost effective. AGM if they're half price or less compared to flooded. Winston cells if you need lightweight high energy density. 18650s for charging yer phone.
If your charger can't charge to specific gravity 1.28 per cell bin it and get a new one. (sigh...I sound like a broken record....and yet Victron is a major player  ::))
 
Holes in the roof? WhaaaaT?
Nah! Hydrocaps!

There's no such thing as a game changer that's a marketing buzz word.
What's the sense in buying a battery so other people can use it?  facepalm
Energy in costs more than energy out..you're signing up to be short-changed.

State storage is not domestic storage.


Title: Re: Are batteries worth it, does this calculation work?
Post by: offthegridandy on September 18, 2018, 08:53:27 PM
Actually it may be if you stick to tried and tested lead acid batteries the equation is not so bad. Off grid experience (years of) so no subsidies etc.

We have 4.5 Kw of PV panels in power production.
This year since February no fully operational WT.
Red diesel cost 2018 to date £285.00
Expected red diesel cost this year £500.
1000Amp 24V FLA battery cost £1600 (2 years ago) give it a 5 year life( will be more like 12 years) so annual cost is £320
£320 + £500 =£820

So our annualised electric cost 4 bed house fully civilised with fridges and freezers UFH etc is £820. And we run a business from here.

I'd  have thought thats' got to be around break even point compared with utility supplied. And depends on life style, if you not trying to run a swimming pool or summat.

I accept I'm  ignoring the cost of the inverters and PV panels but the OP presumably all ready has these and will also be harvesting some grant money. I also ignore the cost of maintaining a Lister generator due to it's potentially near infinite life expectancy.

Depending on orientation and exact set up, for at  least 6  months of the year any surplus over battery charging and house loads could go to charging an EV for free.

One thing to think on though is, how much more you consider energy expenditure if you are directly responsible for the generation.  Eg in mid winter at night I wont use the coffee machine and electric kettle at the same time.  I'll do one then the other and thus avoid tripping the genny on, battery energy expended the same but no diesel burned in genny.


Andy


Title: Re: Are batteries worth it, does this calculation work?
Post by: nowty on September 18, 2018, 09:34:05 PM
Its financially worth it if you can get second hand gear cheap enough. My repurposed growatt lithium batteries have worked out cheaper than my lead acid forklift batteries which have worked out at pretty much cost neutral. Also all my renewable gear has been purchased with borrowed money at cheap rates, all being paid back with my FIT income so its all free anyway. By the end of my FIT period I could put everything in the bin and I will have lost nothing but still had lower elecy bills for 25 years. :crossed

Its technically worth it if you like tinkering / experimenting and seeing how low your import can go. My import for a 4 bed family home is now down to 0.15kWh per day Feb to Oct. exhappy:

Its amusingly worth it when your street has a power cut and you open your curtains and turn on every light in the house. Done this a couple of times. stir:

It will be increasingly worth it as we move to time of use tariffs which is the only way we are going to have enough peak generating capacity for all these EVs and heatpumps. My house is fully TOU ready now. bike:

Its environmentally worth it if you like reducing your CO2 levels. In this case doubly worth it cos you will also have forgone a long haul holiday, a hot tub or other CO2 intensive thing. I don’t see myself as an Eco Warrior but I don’t like waste. :fight

There are probably many more reasons to have batteries (obvious one being off grid), but the above are relevant to me. 8)


Title: Re: Are batteries worth it, does this calculation work?
Post by: Scruff on September 18, 2018, 10:41:45 PM
For laptops and mobiles, there is sod-all to very little,

Wholeheartedly disgree. There is cell/battery mismanagement. Big business; "non-replaceable" componentry & manufactured obsolescence.
The last two phones I had reach 4.1V at 75% charge. 4.35V @ 100%
Makita tool batteries will never take a recharge if you lose power to the BMS or drop them below threshold. Samsung laptops do this too so it is extremely difficult to recell them.
Some laptops have cycle counters and electronically controlled diminishing returns.
Smapple just cook theirs with deliberate oversight on thermal management.

If you root access androids you can confine the charge & discharge thresholds.

50% bigger phone cell with same extracted energy per cycle = 6 times the lifetime cycles.
We ought to stop voting for slimmer devices with our wallets.

Careful what you buy because every time you do you say that's an acceptable product.
If it can't play nice with other manufacturers' equipment then as far as I'm concerned they can go attempt procreation with their headwear.


Title: Re: Are batteries worth it, does this calculation work?
Post by: Scruff on September 18, 2018, 10:53:42 PM
Its financially worth it if you can get second hand gear cheap enough.

Sounds like every piece of power electronics I own.
I've only paid for 4 outtov my nigh 20 batteries.  whistle


Its amusingly worth it when your street has a power cut and you open your curtains and turn on every light in the house. Done this a couple of times. stir:


Ah yes this is my favourite. When trade sparkies tell me solar is unreliable and I point out I haven't had a powercut for 8 years and my motorhome can power buildings.  :P

Remote powah to sheds and sites are another good application.
Liveaboards.
Cabins in ja woods.

I don’t see myself as an Eco Warrior but I don’t like waste. :fight

Second that.

There are probably many more reasons to have batteries

Wireless powah! Because Tesla (Nikola, not the neo-antithesis) Coils are too expensive and complicated.


Title: Re: Are batteries worth it, does this calculation work?
Post by: Tinbum on September 19, 2018, 09:03:57 AM
I was importing 25kWh a day on average and now I do less than 1500kWh a year. Our meters haven't increased since the end of February and opefully our grid consumption will go down with the use of a wind turbine during the winter. I'm just in the process of making the mast. We also now have a heated pool for the kids.

I agree with nowty but it's not for everyone. I do it because it gives me great pleasure.


Title: Re: Are batteries worth it, does this calculation work?
Post by: andrewellis on September 19, 2018, 10:38:59 AM

Holes in the roof? WhaaaaT?
Nah! Hydrocaps!

Is hydrogen release a problem with the lead acid these days.  Should I have them in a shed out with the main building?


Title: Re: Are batteries worth it, does this calculation work?
Post by: Scruff on September 19, 2018, 10:43:48 AM
Not especially. Depends on how big the battery is & how aggressive the charger is. You can vent it, recombine it or ignore it. Just try not to contain it (extremely difficult) and ignite it.


Title: Re: Are batteries worth it, does this calculation work?
Post by: Sprinter on September 19, 2018, 12:35:32 PM
"Are batteries worth it", Depends if your only interest is financial to be honest.

I installed batteries without too much regard for "will they ever pay for themselves", my motives are as followed:
  • I am earning more money now that i am likely to earn later as i get older (55 so retirement is only 10 years or so away)
  • I wanted to use some of the spare cash i earn now to offset my reduced income as i get older and or retire giving me more free cash for fishing and boating stuff
  • I despise giving so much of my money to the utility services that are ripping everyone off (batteries allow me to hand over less cash for many, many years)
  • I wanted to be greener or more kind to the environment by using more of my home generated juice
  • I wanted a backup system that will keep my 360 LTR fish tank warm and my fish alive in the event of a power cut
  • I will definitely get a better return on my batteries over decades than i will from my company pension as they force closed the scheme last year
  • FITS gives me money every month for more assumed export than i have used myself, where previously they gave me less money than the amount i was exporting, this pleases me :)  

I guess like many i hope they will pay for themselves, but if they don't, i dont care as they are now bought and paid for so in my mind they are now saving money every month and will continue to do so for years, and i would only have thrown that money away of motorbikes, cars of fishing rods, this way i am a little better off each month.


Title: Re: Are batteries worth it, does this calculation work?
Post by: kristen on September 19, 2018, 04:34:12 PM
Interesting discussion, thanks chaps.

I'm a bit of an eco-warrior - wife says we don't get invited to dinner anymore because I spend the whole evening haranguing my range-rover-school-run-driving hosts ...

Although I'm changing my tune from using absolutely minimum energy to having comfort, and producing/storing my own energy so that I don't consider extravagant use to be "waste", because I hate waste with avegence.

"Why did you leave that light on? How am I suppose to get the energy it used back in the bottle?"
"Chill Dad, the Roof made that energy ..."

A conversation on here a few months back (sorry, forgotten who with) changed my mind from night-venting to cool our Passive House on hot summer days to installing reversible heat pump to put cold water through UFH to cool the floor instead (and by not opening the windows also not let the flies in ... and also not have the day temperature creep up to 25C in a mega-heatwave which is a tad hot if you are just sitting still and don't have a fan on)

Insulate ... Insulate ... Insulate

Done that, but I started with reduce ... reduce ... reduce ... I read the meters and measured the oil-tank each week, and made a graph. We cut our electricity use by 50% and our oil by something significant, and then switched to biomass. That switch cost a fortune .... but oil price (unexpectedly) shot up and all my mates who originally thought I was several Prawns short of a Barbie were jealous and asked about my crystal ball.

The Tesla purchase was 3x what we normally spend on a car. Brexit then caused the pound to cave, and two years on the car is worth close to what I paid for it ... and driving is less than 3p a mile for Fuel and saving me £4,500 a year on fuel (27K miles p.a.)

So Lady Luck has sponsored my Eco Follies.

But ... I'm knocking on a bit ... removing variability from my fuel costs, by spending on Capital now, has appeal for my retirement and being able to retain both my lifestyle but also not becoming old and in a cold, draughty, damp house.

I too want to be 100% "Time-of-Use Tariff Ready" and take advantage of that.

If power company is happy to pay me on assumed 50% export of my PV I'd be a mug not to export zero units or not to install the maximum amount of PV that they will let me grid-tie.

If I'm going to get a battery I will have to buy PV too (maybe only a 1ft square panel?!) to get the reduced VAT ... and I want to do that before next spring before the FITs go away.

Physiologists said BEVs owners have better karma when driving. They couldn't figure out why; maybe because BEVs are quiet, or maybe because owners are pleased to be doing their bit. So if ECO-SMUG is going to make me feel better then I need more PV, more Battery, more Heatpumps ...

Lots of reasons to do it, but mostly because it seems to have worked out alright for me, despite the what the maths said at the time.


Title: Re: Are batteries worth it, does this calculation work?
Post by: billi on September 19, 2018, 08:09:16 PM
Batterries just helped me to get more independant , i jus dislike the fact of beeing controlled ,  not thinking allways aboutz dollars  , was and is worth while the studdy , and my battery is 15 years old now 


Title: Re: Are batteries worth it, does this calculation work?
Post by: pantsmachine on September 20, 2018, 12:21:12 AM
I haven enjoyed reading this thread and the views on the subject.

My old deal with power company a couple of years ago was 8.6p then 13.4p then 15.8p and is now 16.34p fixed until 2020. That is all the financial justification i needed to make to myself.

I like the independence, I like the clean power, i enjoy the added PV efficiency of use of our own power that the batteries give.

I like the battery graphs which have allowed me to see the massive burn rate of our 4 fridge & freezer units. This will be addressed.

I like the idea that i can add to the system and disconnect further from the grid if i choose to and conditions allow.

Great to read of others and the reduce aspect due to raised awareness and also the 'chill' element once been out there to the extreme.

There is a non quantified value in knowing that as you age you will not be at the mercy of rising prices but will instead be sitting on your holidays while your home ticks over at no cost and earns, That thought is priceless.

Some of the above are intangibles but only in money terms, the value is still there and can be felt every day. A part of me thinks it mildly strange that so much focus is brought to bear on the returning of cost at the pounds and pence end, that focus misses quite a lot of the benefits.

An example, I'd love to think i could install a low cost heater in a polytunnel running off the batteries and go chill there in the Winter months.


Title: Re: Are batteries worth it, does this calculation work?
Post by: Scruff on September 20, 2018, 12:54:10 AM
1kWh for campervans from a campsite socket is between €3 & €5 in Éire. Another €25 for the pleasure of parking beside the outlet.
60 cell solar panel payback = 4 nights.  bike:


Title: Re: Are batteries worth it, does this calculation work?
Post by: eabadger on September 20, 2018, 07:49:46 AM
where we live most people heat water with electric and heat odd rooms with electric in the winter supplemented with a wood stove or fire.
my next door neighbor does this and spends €2200 on electric a year.
so was our initial investment and updates been worth it? well no EDF bill for 7 years and the thought of not having a big bill on the way is great, we do use red diesel to charge in winter but the usage is dropping and cost is negligible.

would i recommend it? is it worth it? as a lot have said above if you like tinkering then yes if not, i think no.

steve


Title: Re: Are batteries worth it, does this calculation work?
Post by: heatherhopper on September 20, 2018, 11:56:00 AM
I applaud anyone trying to distance themselves from the corporate grid structure but the sobering fact is that we are all intrinsically tied to it by virtue of our lifestyles - even us off-gridders whose numbers are sadly limited by means and circumstance. True eco -warriors are hard to find.

I am unconvinced by the merits of domestic grid-tie batteries on all levels. I perceive the current raised profile to be driven primarily by consumer sales interests and the all pervasive obsession with "new tech". The possibility of having such a thing is, after all, not exactly new. I think enthusiasm, time, money and effort would be better spent pressing for a rational, sustainable and equitable national grid structure rather than adding more layers of stuff and complexity at the domestic level.

That said I am interested to hear about the performance of the alternatives to FLA batteries - the emphasis here being on real world data and not lab testing or agenda based evidence trawled off the web. Trouble is this information will only be useful many years hence and probably beyond my active interest. The other perennial problem is that real world experience from battery owners is traditionally often economical with the truth about the circumstances of use. Apparently most FLA (even s/h) installations live longer than even the manufacturers wildest dreams! This may not be untrue - probably depends how they are used, but this is either a bit of a secret or not really known. Things do not look like changing much as within this thread alone there are several different and selective descriptions of performance, none of which tell me much I could rely on to make a decision.

There was a time the first piece of simple advice offered to anyone wanting to detach themselves from the grid was to fully understand their generation patterns and consumption needs, reduce consumption to what is actually necessary and then determine the best installation. Seems this fundamental first step is in danger of being skipped in favour of  "I must have a domestic battery - now how can I go about justifying it". Perhaps a bit more in-depth monitoring and then some simple time shifting of consumption might be a better starting point for most people - loads of options available at little or no cost to achieve this.

I have only one reason for having a battery bank - if I didn't the lights would go out unless I clocked up a financially unacceptable number of generator hours. I have no love of the battery bank - it is the single most expensive renewable energy item I have, it produces nothing and consumes a fair bit, buys a variable and unpredictable amount of autonomy, it's longevity is an unknown and when it does give up the ghost I will probably need to spend a similarly large amount again to replace it. The battery is necessary for an uninterruptable off-grid set-up with sustainable pretensions, if I were connected I think it would simply be another gadget.

Although I am not enamoured of my FLA battery bank I don't really understand where all the talk of them being hard work and a lurking hazard comes from. I spend little time actually doing anything with mine - 10-15 minutes water top up and general faffing about every 4-6 weeks. Sure I monitor it's status and have poked around with some charge control settings but the attraction soon wanes unless you start inventing reasons for more fiddling. I can't imagine what extra excitement there would be in having a Lithium fit-and-forget box under the stairs. With no proven track record I think the Lithium would worry me a bit more.

I'm sure there are people with real and genuine reasons for wanting a grid-tie battery as in some of the above posts. Interesting that the justification seems to have whittled down from some less than clear financial  reasoning to mostly a feel good thing. Nothing wrong with that as a personal choice and certainly more credible. Can't see why the general populace would want one though - only a tiny proportion have PV and that was a financial no-brainer with uncontrived green credentials. Probably going to remain a niche item for the foreseeable then (with all that entails) despite the best efforts of the "renewable industry" PR machine and acolytes to kick start it up the ladder.

I say an unashamedly self-interested "good luck" to all those Lithium enthusiasts and look forward to future objective reports regarding the performance of their batteries in whatever circumstances they are used - won't hold my breath on the objective bit though.


Title: Re: Are batteries worth it, does this calculation work?
Post by: kristen on September 20, 2018, 02:28:43 PM
I am unconvinced by the merits of domestic grid-tie batteries on all levels. I perceive the current raised profile to be driven primarily by consumer sales interests and the all pervasive obsession with "new tech".

I share your view, but speaking for myself:

I work from home, my wife too on occasion, and a couple of other (office folk) work from-here too.  We also have servers that are accessed from remote. A power cut is a PITA on two counts - firstly that any work-in-progress is lost (except where we have individual UPS, but they are without exception cheap-and-cheerful and fail sufficiently often to be almost as bad as the power cuts themselves) and secondly from the loss of remote accessibility.

A whole house backup battery would be great, but even one that tripped (to disconnect from the grid) and then allowed continued working would be sufficient.

PowerCuts here are frequent (at least once a month) and normally last a few seconds, sometimes a few minutes, and once or twice a year for a few hours (e.g. JCB dug through the cable). Scheduled downtime is probably a once or twice a year thing - e.g. cutting overhanging branches

So I have "lost billable hours" / "increased cost of working" to offset my battery purchase against.

At the absolutely opposite extreme I'm not sure "not having to reset all the electric clocks in the house", after a powercut, would be sufficient justification!! but there may well be some folk that are somewhere in the middle?

Car EV battery connected to house might become a thing but, personally, I don't want to get home and then discharge my car into the house ... I might need to drive somewhere urgently ... I'd prefer to come home and plug in, although currently I schedule charging for E7, so in practice I don't charge from arrival at home until midnight (but I do charge immediately if I arrive home below 20% because its better that the battery is not left in that state, and "I might need to drive somewhere urgently")

A distributed battery system, at a local-ish level, would achieve better economies of scale than individual-dwelling-batteries, but would it achieve the same up-time for each house? Residential installation also enables, maybe?, the power companies to offload the capital cost of batteries to consumers ... can't see us getting lower cost-per-unit in return though, eh?!! Although when TOU arrives maybe I will be able to sell my stored juice at peak for a worthwhile price

Quote
That said I am interested to hear about the performance of the alternatives to FLA batteries - the emphasis here being on real world data and not lab testing or agenda based evidence trawled off the web

Dunno if it is useful data, but there is data for Tesla batteries used in their cars (which have a decent battery-management-system). Taxis with very high mileage, somewhat abusive charging - high kW charging, often charging to 100% and leaving the battery in that state (normal daily recommendation is to charge to 90% and if charging to 100% "set off promptly"). At around 200,000 miles (battery range approx 200 miles, but I don't know how often discharged to low state-of-charge, so maybe approaching 1,000 cycles - typically they are approaching 100,000 miles p.a. e.g. airport-run taxi companies) battery degradation is around 6%, and it seems that most of that happens early on, and levels off thereafter.

Quote
fully understand their generation patterns and consumption needs, reduce consumption to what is actually necessary and then determine the best installation. Seems this fundamental first step is in danger of being skipped in favour of  "I must have a domestic battery - now how can I go about justifying it"

Telsa (and I'm sure others) have some fancy graphs on their APP showing where the battery / PV has been used/charged relative to grid import/export.  That's after-the-installation of course, and doesn't tell you that your Fridge has a filthy condenser grill and just cleaning that would dramatically reduce consumption (Yeah, BTDTGTTS ...). They also have an open API, so opportunity for doing "stuff" with the data.

Jaguar have provided an APP that records your (normal, current) journeys and then makes recommendations on how your life would be / cash-savings etc. if you bought their i-Pace EV.  Maybe similar APPs exist for Smartmeter folk to show cost effectiveness of PV, Battery-installation, etc.  Its a lot different for someone using energy during the day, when PV would help, to someone who is out to work all day.


Title: Re: Are batteries worth it, does this calculation work?
Post by: Scruff on September 20, 2018, 07:43:23 PM
Heather H; I heart your point of view.

Kristen can you share with the class this Neo-Tesla "data" please?
Would you mind awfully citing the source and verifying the fidelity?

In the summary can you explain to me the following:

How does it compare to the device's projected longevity and functionality info? If you can find any.
What is the cycle depth in these figures? Can you express it in terms of total energy extracted instead of cycles?  Does this meet specification? What is the specification?
Are users pushing this technology to 100% claimed duty cycle or if not what is the nominal duty cycle generally seen by users?
What is the Neo-Tesla battery round trip efficiency independently tested figures? What is the 100% charged per cell cut-off voltage...and the 0% Charged Cut-off voltage? What are the parameters by which they measure battery degradation?

Did you know that Neo-Tesla rate their batteries down to 70% of original capacity while all the rest of the scientific community have agreed on an 80% threshold? Did you realise this disqualifies them from comparative testing with their peers?

What is the true lifetime cost of a kWh from a Neo-Tesla PoowerWall?
What is the PoowerWall self-consumption in ambient -5°C at night?
Does it work in a powercut?
Can you charge it from utility mains or a genset?


Title: Re: Are batteries worth it, does this calculation work?
Post by: Scruff on September 20, 2018, 08:02:11 PM
If the best we can seem to get is a 80% round trip efficiency from every conceivable battery option in production why is everyone obsessed with chemical batteries instead of mechanical? Cathodes degrade faster than turbines!
A mechanical battery is every bit as efficient as a chemical one but more upscalable, less volatile, less toxic embedded energy and lower self-consumption.

I'm taking about State Level Storage here:

Compressed Gas Caverns.
Pumped Hydro.
Tidal Storage.
Magnetic Bearing Flywheels.
High Altitude Rainwater Catchment.
Electrolysed Hydrogen (ok not 80% efficient or anything like it)
etc...


??

Split tarriffs reflect demand economy not energy efficiency.
This current model of demand economy only makes sense because the state has no decent batteries at their disposal!   

 linux:


Title: Re: Are batteries worth it, does this calculation work?
Post by: andrewellis on September 20, 2018, 09:40:02 PM
Exactly, given the problem of most of the power being generated in the summer, some way of taking it through to the winter would be great.  Audi has an interesting project which makes diesel from water and co2 at a reasonable efficiency.  If the technology is scalable to the garage that would be amazing.  Just fill your tank and run a generator in the winter.  Ok, the round trip efficiency is not brilliant but if you have the land you wouldn't need to put aside too much to get through the year. I doubt this will happen in my lifetime.


Title: Re: Are batteries worth it, does this calculation work?
Post by: Scruff on September 20, 2018, 10:07:13 PM
Here's a good argument for electrolysing hydrogen.

Clicky (https://www.telegraph.co.uk/news/2018/01/08/wind-farms-paid-100m-switch-power/)


Title: Re: Are batteries worth it, does this calculation work?
Post by: brackwell on September 20, 2018, 10:37:56 PM
This is old news because that was before the Western HVDC link  which was built especailly to address this problem. Constraint payments also take place for other forms of leccy production remember, and they are a cost effective means of managing the Nat Grid.  The Western Link cost c£1B.  The constrained amount of leccy is peanuts compared to energy demand.  Anyways off topic.

Ken


Title: Re: Are batteries worth it, does this calculation work?
Post by: Scruff on September 20, 2018, 11:13:02 PM
Old news or nay.

More turnips = more powah = more hydrogen = morah powah!

 exhappy: exhappy: exhappy: exhappy:


Title: Re: Are batteries worth it, does this calculation work?
Post by: Scruff on September 20, 2018, 11:17:00 PM
...but fill the gas caverns first^ (http://www.navitron.org.uk/forum/Smileys/classic/onpatrol.gif)


Title: Re: Are batteries worth it, does this calculation work?
Post by: pantsmachine on September 21, 2018, 12:54:36 AM
We could wait a long time for government action on a large scale which should not preclude us from carrying out our own small scale endeavors. Same for efficiencies in accessible tech. Entropy is in everything and unavoidable so not a reason to choose not to but instead a consideration to be taken into account imho.

In saying the above, On a larger scale I have been impressed with SSE's offshore wind farms and their commitment so will be increasing my investment in them which is going off topic but only to show that my focus can be macro as well as micro.


Title: Re: Are batteries worth it, does this calculation work?
Post by: Scruff on September 21, 2018, 01:04:00 AM
I don't advocate not to do anything. I'm saying if you do do, do it sensibly and learn to differentiate between marketing BS and practical applications.


Title: Re: Are batteries worth it, does this calculation work?
Post by: pantsmachine on September 21, 2018, 01:05:22 AM
As am I. I would also throw out for thought that the chemical batteries with BMS are zero maintenance and qualify for a 'fit & forget' badge of merit. In my roving lifestyle where i can be away from home for long periods of time this is appealing.

It is likely to be appealing to a large percentage of the people going forward after the FIT's end. The tech price will hopefully continue to drop and those who choose to buy into PV will be doing it as a lifestyle choice and may see more value in 'fit & forget' rather than cost/return ratio. This last is entirely conjecture and largely from the coffee i have just consumed.

I am already tempted to buy a 3rd battery, say damn the cost and focus on the benefits of the excess PV generation it will store on the good days. Admittedly this does not take into account the cost of its manufacture & transportation from China to my home in Scotland but I only allow myself to obsess so far! I would love to see green mass storage come online, (it kills me when i see wind turbines idle) and will react accordingly when it does. I am going to read about gas caverns now.

I am currently involved in an offshore project which is producing 2 billion cu ft NG per day for Egypt 165k offshore at a WD of 1,500 mtrs. First time Egypt has even been self-sufficient in NG. Its not green, its not particularly cool BUT its not being transported across the globe and is a close source for the country. Different perspective...


Title: Re: Are batteries worth it, does this calculation work?
Post by: Scruff on September 21, 2018, 01:56:39 AM
In my roving lifestyle where i can be away from home for long periods of time this is appealing.

(https://www.smiley-lol.com/smiley/fatigue/sendorq.gif)
Use FLA.  Lose the BMS, turn the absorption down to 2.37V per cell.
Lots less likely burn yer house down with thermal runaway if it gets too hot or cold because a semiconductor fails or failsafe by isolating entire modules.

I am going to read about gas caverns now.

Find a large salt deposit. Inject pressurised hot water. Pump out saline. Congrats you've made an underground cavern. Fill it with pressurised air with abundant energy. Vent it through a pneumatic turnip when you want to extract power from your immortal battery. Simples.


Title: Re: Are batteries worth it, does this calculation work?
Post by: pantsmachine on September 21, 2018, 02:26:17 AM
Thanks,
I appreciate the feedback. I'll look into both highlights as applicable.

Heather H
'There was a time the first piece of simple advice offered to anyone wanting to detach themselves from the grid was to fully understand their generation patterns and consumption needs, reduce consumption to what is actually necessary and then determine the best installation. Seems this fundamental first step is in danger of being skipped in favour of  "I must have a domestic battery - now how can I go about justifying it". Perhaps a bit more in-depth monitoring and then some simple time shifting of consumption might be a better starting point for most people - loads of options available at little or no cost to achieve this.'


I agree wholeheartedly with the above, its a huge part of it and is a simple 1st step to taking control of power consumption. I currently have a 200 watt background drain on the house and i will be addressing it on my return to base. It has a massive impact on the battery charge overnight and the game now is 'how low can i go'? A benefit of PV & battery of which i was previously unaware and had not considered.


Title: Re: Are batteries worth it, does this calculation work?
Post by: Nickel2 on September 21, 2018, 07:18:19 AM
With the increasing number of EV's forecast to be on our roads, is it better to have the wind generation ready and sitting in standby, or wait until everyone is charging their cars at the same time and the grid collapses? There is also the question of electric traction on the railways. Many new MU trains are power-hungry beasts with rapid acceleration and aircon. There have been studies recently that investigate the different types of traction-motor operation and how each draws power from the grid. (electronic poly-phase or D-C field control etc).
I would rather there be an excess of generators that have to be paid for, than a national collapse when fossil fuel generation winds down.
N2


Title: Re: Are batteries worth it, does this calculation work?
Post by: kristen on September 21, 2018, 07:38:05 AM
Kristen can you share with the class this Neo-Tesla "data" please?
Would you mind awfully citing the source and verifying the fidelity?

Can't attest to anything I'm afraid. As a news article it has probably appeared in a number of places, here is one such:

https://techcrunch.com/2016/09/29/tales-from-a-tesla-model-s-at-200k-miles/

That's a  Los Angeles - Las Vegas taxi, I've also read of a Dutch taxi with similar 6% degradation (my recollection is that was an airport-run taxi firm)

Quote
In the summary can you explain to me the following:

No don't think I can help with anything at that sort of level, I have no first hand information; however I think it likely you will find people that can answer such questions on a Tesla forum. There are a couple to choose from, but in terms of general discussion I would suggest Tesla Motor Club. It has a specific forum for Tesla Powerwall (mostly installation stuff, but there are some geeky folk there interested in collecting data etc etc and some technically-astute folk too, and (on the car side) some folk who have taken them to bits, "rooted" them, done write-off repairs (which is outside ANY support that Tesla is prepared to provide ...) and so on.

https://teslamotorsclub.com/tmc/forums/tesla-energy.159/

There are several generic sub-forums on that site, but I wouldn't say that battery performance is discussed much (in the sense that its not regarded as a problem) but you might have some joy in the Technical : Battery forum

https://teslamotorsclub.com/tmc/forums/battery-discussion.40/


Title: Re: Are batteries worth it, does this calculation work?
Post by: kristen on September 21, 2018, 07:54:31 AM
wait until everyone is charging their cars at the same time and the grid collapses?

Clearly we're going to need a solution for that scenario!

I'm imagining that smart meters and TOU will be the solution. Not sure I've found a good source (figures seem very low) but RAC report suggests that average car/van commute (accounting for 57% of UK population's commute) is 10 miles. My single-phase wall charger does 22 MPH, so 10 miles could achieved with half-an-hour sometime during the night.

I think also the possibility that charge-at-work will become a thing, which could mop up Solar excess when available.

So: nick the electricity at work to fully charge the car, come home, discharge car battery into grid at peak TOU for max-$$$ and then buy dirt cheap overnight surplus electricity, just enough to get to work :)

Page 11:
https://www.racfoundation.org/assets/rac_foundation/content/downloadables/car-and-the-commute-web-version.pdf


Title: Re: Are batteries worth it, does this calculation work?
Post by: brackwell on September 21, 2018, 08:10:39 AM
 wait until everyone is charging their cars at the same time and the grid collapses?

Just not going to happen with demand being much more spread out but also TOU tariffs with smart meters will incentivise against that. The problem may arise with the very local network not being able to cope on a street by street level.
Ken


Title: Re: Are batteries worth it, does this calculation work?
Post by: andrewellis on September 21, 2018, 08:41:19 AM
It'll be interesting to see what will happen in the sticks too.  We have a 10kw transformer serving 3 houses.  I have a 60A fuse and I am guessing the neighbours have the same too.  As a worst case experiment I turned on the dishwasher, tumbledryer, GSHP at -6deg C,and charged the car.  The cooker on order is a range to try and avoid the massive instant power draw.  This came close to the 60A (14kw) very easily.  However, we are using as a single house more than the transformer rating so it will be interesting to see what happens this winter. 

As a comparison I've been doing some reading on the Nissan battery.  The original 2011 battery (24kwh)would appear to be at 50-60% charge after 150000 miles.  That would be the equivalent of ~1200 cycles from the battery.  The newer models appear to be performing better with some (few) meeting 95% capacity after 100,000 miles.  The battery treatment over the life time also appears to make a huge difference.  The general trend seems to be for 70% at 120-150,000 miles.  I do wonder if all these home batteries really will make 6000 cycles.

Supposedly all the technology is in the car to charge and discharge to from the house. It's a shame that we can't just drop the battery and plug it into a small controller to the house.  It would appear that the company is trying to make money by recycling the battery themselves and charging a ton of money for the privilege.  Given how charging/discharging rapidly reduces the capacity of the battery I am not sure I would want to use it as a conventional PV battery.  It seems like a nice idea on the face of it, but would prove to be an expensive way to age the car quickly.  Then Nissan could then charge a large amount of money to swap out the battery.


Title: Re: Are batteries worth it, does this calculation work?
Post by: phoooby on September 21, 2018, 09:01:59 AM
OVO offer a V2G unit https://www.indra.co.uk/v2g/ with DC connection to connect a leaf. Buy second hand leaf and charger and leave it in you garage/drive. 20kWh home battery that is probably cheaper than x2 PW" or other options and with the added benefit you can use it to drive to the shops.

There is an OVO product to go with this where you buy cheap and sell at peak to gain a few hundred pounds per year. Not sure what V2H benefits it offers as not looked into it too much.



Title: Re: Are batteries worth it, does this calculation work?
Post by: andrewellis on September 21, 2018, 09:45:07 AM
Oh, now to persuade my missus to let me build a little shed for the car, ahem i mean battery unit. In fact, I can put the car where the oil tank was!


Title: Re: Are batteries worth it, does this calculation work?
Post by: skyewright on September 21, 2018, 10:14:59 AM
In saying the above, On a larger scale I have been impressed with SSE's offshore wind farms and their commitment so will be increasing my investment in them which is going off topic but only to show that my focus can be macro as well as micro.
Also off-topic, but SSE are also involved in several new pumped storage schemes. Around here most people still think  of them as Scottish Hydro.


Title: Re: Are batteries worth it, does this calculation work?
Post by: brackwell on September 21, 2018, 10:25:45 AM
I wish they would get on and build the one on the side of Loch Ness.  They are obviously waiting for more favourable financially.  Up in Scotland the grid charges are greater, because they are further away from the cities and pumped storage ends up paying twice both to and from.  When the Scottish Islands get going the storage will become even more imperative.  The Gov needs to tell the Nat Grid to mend its ways and without any bung.


Title: Re: Are batteries worth it, does this calculation work?
Post by: Scruff on September 21, 2018, 10:38:42 AM
Can't attest to anything I'm afraid.

Interesting. Do you not find it alarming that the basic operation parameters of the battery is not published? Who benefits the most from this do you think?
I could answer most of these questions from the datasheet of a genuine manufacturer for any battery I would consider buying.

Do you think people would be as willing to buy an equally ambiguous amount of say diesel or would they like to know the volume?

...Tesla batteries used in their cars (which have a decent battery-management-system).

What did you base this statement on so given you can't even tell me the upper and lower voltage cut-offs?


I've also read of a Dutch taxi with similar 6% degradation (my recollection is that was an airport-run taxi firm)

Moving 1.5ton with wheels 200 000 miles is not such an achievement as I think you believe it is, that battery is lightly worked compared to the claims.

No don't think I can help with anything at that sort of level, I have no first hand information;

Curious.
Why advocate it so?
Doesn't bother me, it's a proprietary system. Not something I'd get involved with.


Title: Re: Are batteries worth it, does this calculation work?
Post by: Tinbum on September 21, 2018, 11:03:27 AM
I wish they would get on and build the one on the side of Loch Ness.  They are obviously waiting for more favourable financially. 

https://assets.abundanceinvestment.com/docs/projects/investment-updates/2018_07_02_ILIPumpStorageHydro_update.pdf


Title: Re: Are batteries worth it, does this calculation work?
Post by: brackwell on September 21, 2018, 11:11:07 AM
I was referring to the Coire Glas one by SSE which has had planning permission for some yrs now.


Title: Re: Are batteries worth it, does this calculation work?
Post by: RIT on September 21, 2018, 11:45:43 AM
With the increasing number of EV's forecast to be on our roads, is it better to have the wind generation ready and sitting in standby, or wait until everyone is charging their cars at the same time and the grid collapses? There is also the question of electric traction on the railways. Many new MU trains are power-hungry beasts with rapid acceleration and aircon. There have been studies recently that investigate the different types of traction-motor operation and how each draws power from the grid. (electronic poly-phase or D-C field control etc).
I would rather there be an excess of generators that have to be paid for, than a national collapse when fossil fuel generation winds down.
N2

The whole point of smart meters is to allow for "time of use" tariffs, so the grid will be well prepared for when electric cars show up in volume.

With TOU pricing all home charging will take place overnight when the grid has about 10GW of spare capacity. During the day TOU pricing will mean that users end up paying the costs of purchasing additional generation capacity to keep up with demand.


Title: Re: Are batteries worth it, does this calculation work?
Post by: MeatyFool on September 21, 2018, 01:23:01 PM
The car in the garage as a home battery is my hope!  Gen2 Leaf is capable of charging from and discharging to the house, but my 2015 Leaf is not able to do so.

I was hoping that in 4-5 years time someone will have developed an after-market product that essentially bypasses the standard drive train.  Not sure it is even possible!

Of course, in 4-5 years time, the cost of a domestic battery may be much lower, so that the trade-in value of the car plus the "gizmo" is as much or more than the equivalent storage capacity of fresh batteries.

Meatyfool..


Title: Re: Are batteries worth it, does this calculation work?
Post by: phoooby on September 21, 2018, 02:34:03 PM
Meatyfool. As per my link posted above, Indra have made a V2G system using the chademo DC connection. From what I understand they are making these for OVO and will eventually sell them in their own right, presumably for V2H purposes. Might be worth contacting them to see how much they are and when available. Apparently works on all gen 1.5 onward leafs (the ones without the electric handbrake).


Title: Re: Are batteries worth it, does this calculation work?
Post by: MeatyFool on September 21, 2018, 03:27:29 PM
Thanks phooby.

My mistake - I thought it only worked for Gen2 onwards.  I did apply to take part in the trial, but after applying realised that I didn't fit the trial requirements (can't remember why!)

Meatyfool..


Title: Re: Are batteries worth it, does this calculation work?
Post by: MeatyFool on September 21, 2018, 03:39:50 PM
Phooby,

Just checked the OVO indra link - not quite what I had in mind.  The unit discharges back to the grid rather than into the home.  So OVO gets to use some of my car charge to sell on and gives me a portion of that sale back as my incentive.

As opposed to me being able to discharge from my car at a time of my choice (TOU - peak time), which *might* be better for me.

If I remember correctly, there was quite a discussion here regarding the financial implications when it was first launched.

Meatyfool..


Title: Re: Are batteries worth it, does this calculation work?
Post by: heatherhopper on September 21, 2018, 09:05:44 PM
I am constantly reminded of a slight variation on the square hole round peg type game when reading some of the visionary speculation regarding integration of batteries, EVs etc with the grid. Normally a straight forward puzzle and great cognitive development for infants but have you ever watched a child who has been given access to shapes that look more attractive than the correct ones but don't quite fit, with an added incentive of a brownie point if they do manage to fit them in. Good fun to start with but certain to ends in tears and tantrums.

Scruff - you have me paranoid about my Makita batteries. They look absolutely fine on the outside, sort of..... well, fit and forget. Are you telling me there is something fiendishly unknowable lurking inside?


Title: Re: Are batteries worth it, does this calculation work?
Post by: phoooby on September 21, 2018, 09:32:23 PM
Meatyfool. Yes it seems to be V2G at the moment. I read about it and concluded they thash the living daylights out of your battery and give you £2-300 pa. I decided it was not for me despite them saying it would actually benefit the battery as charge/discharge would be managed. Probably a good idea for someone with a company car or leased leaf.

Maybe they will offer the same unit as V2H in the future so it can be used for home PV storage and you are not tied to OVO. I can see that being a good idea as you get a much larger battery to store PV and the unit would hopefully be cheaper than buying separate batteries. Nissan seem to have made something but I seem to recall it was going to cost over £3000. Also found this article from this year. https://www.zap-map.com/franklin-energy-and-powervault-partner-for-smart-home-charging/#more-40556


Title: Re: Are batteries worth it, does this calculation work?
Post by: Scruff on September 22, 2018, 12:08:24 AM
I am constantly reminded of a slight variation on the square hole round peg type game when reading some of the visionary speculation regarding integration of batteries, EVs etc with the grid. Normally a straight forward puzzle and great cognitive development for infants but have you ever watched a child who has been given access to shapes that look more attractive than the correct ones but don't quite fit, with an added incentive of a brownie point if they do manage to fit them in. Good fun to start with but certain to ends in tears and tantrums.

Agree

Scruff - you have me paranoid about my Makita batteries. They look absolutely fine on the outside, sort of..... well, fit and forget. Are you telling me there is something fiendishly unknowable lurking inside?

Not at all, they're among the best in the business and the bigger the better in terms of longevity...double the price = 3 times the battery.
Samsung cells usually.

All I'm saying is if you stick a light bulb where a drill ought to be and forget about it, where the per cell voltage drops below ~2.6V they will never recover because they are electronically failsafed. You'll have to reflash the BMS to get it to play nice and most people can't.
This also means if you attempt recelling them then you have to maintain power from an external source to the BMS at all times and not let the smoke out with a conductive pokey jabber in the process.

They are state of the art batteries...if you're not in the habit of invalidating warranties you have nothing to worry about.


Title: Re: Are batteries worth it, does this calculation work?
Post by: jonesy on September 22, 2018, 02:07:50 PM
This also means if you attempt recelling them then you have to maintain power from an external source to the BMS at all times and not let the smoke out with a conductive pokey jabber in the process.
Dell used to, and probably still, so this. Really ticked me off at the time as I trashed the bms during a re-cell. I will have to do my research for the next tools. I've re-celled my Dewalt 3 times and onto the 2nd chuck.
I understand why they do it; 2 new original batteries for my dewalt cost just shy of the new replacement.


Title: Re: Are batteries worth it, does this calculation work?
Post by: Scruff on September 22, 2018, 02:14:19 PM
I can vouch for ACER batteries being completely dodo dead when the laptop says so.
I made an underwhelming boomstick from them.

Never had as much success with recelling and just whacking a 12V plug on 'em.

My hitachi 14.4v drill is 15 years old.


Title: Re: Are batteries worth it, does this calculation work?
Post by: Nickel2 on September 23, 2018, 08:13:36 PM
Purely as a matter of interest, It appears that Nissan have teamed up with Eaton to re-purpose used EV batteries for use in home energy storage.

 <https://www.youtube.com/watch?v=sBlFmLyJchM>

I know this article is a few years old, but has anyone noticed anything new from this partnership? did it develop?


Title: Re: Are batteries worth it, does this calculation work?
Post by: RIT on September 24, 2018, 01:05:06 PM
I know this article is a few years old, but has anyone noticed anything new from this partnership? did it develop?

They have an active product called xStorage, but when I got a quote it was well above other solutions we have touched upon in these forums.