Navitron Renewable Energy and Sustainability Forum

Energy/Electricity Storage and Use/Grid Connection => Off-Grid, Batteries & Inverters => Topic started by: Jonah on March 15, 2016, 07:15:46 AM



Title: New battery needed....
Post by: Jonah on March 15, 2016, 07:15:46 AM
Hi all,

I've finally had enough of my old batteries as after a life of abuse I'm finally happy to admit I've ruined them and they need renewing...

The system used to run our off grid farm but now we have mains. I have 4kw of Pv, midnite solar charge controller and 2 Victron inverters and 1100ah of 48v lead acid batteries and use the system to run all the day to day stuff and the Victron use the main every time the kettle or washing machine goes on. 

Question is, lead acid or lithium ion?  I know that financially it probably doesn't make sense but I happy to play and tinker. I've been looking for a leaf battery or something but nothing has turned up and I'm a little concerned about bms.

Can anybody advise please based on experience with their systems?

Thanks

Marc


Title: Re: New battery needed....
Post by: Fionn on March 15, 2016, 08:14:40 AM
I know where you can pick up a leaf battery for 2200 + delivery with low "mileage" on it.

Hard to look past lithium in my opinion, great cycle life, more compact and far easier to manage.
Just set up redundant dump loads to ensure it never goes above 4.1v/cell and a low voltage disconnect at 3.7v per cell and you're done really.
Loads of cheap BMS systems about and easy to configure it for 48V (LA equivalent) operation with 7 modules in series.

Lithium is really far easier to use than LA, the sole disadvantage is it's not tolerant of over charge or discharge, protect against both of these and it's very straightforward.
No need to worry about charging rate, discharge rate, sulfation, toppping off water, boost charging.
You can leave it indefinitely at mid capacity with no capacity loss - in fact it's ideal to keep it mid way for optimum shelf life.
Determinging state of charge is as simple as checking resting voltage per cell.


Title: Re: New battery needed....
Post by: baker on March 15, 2016, 08:42:05 AM
where
and do you get the bms system and charging leads?
baker


Title: Re: New battery needed....
Post by: billi on March 15, 2016, 09:39:28 AM
...My  0nce  40 kWh   Lead acid battery is now about 12 years old   ,  would  consider it again ,  but with electrolyte string idea  , a 30 kWh bank is about 2000


Title: Re: New battery needed....
Post by: Fionn on March 15, 2016, 09:45:10 AM
If you look up there's a thread on here by user Offpiste IIRC that did it.
The easiest way to hook them up is to use 7 modules in series for a 14S battery which will give an operating voltage range similar to a 48V lead acid system.
You would have 6 strings in parallel if you used 42 modules or a 21kWh battery with 6 modules left over.
There are lots of BMS systems available.
Personally I'd buy 12 of these:
http://www.progressiverc.com/celllog-8m.html
They are highly accurate cell monitors.
You would have monitoring of every individual cell on all 6 strings.
The alarm outputs of the monitors can be configured to operate at precise low and high cell voltage limits.
The paralleled alarm ouputs could then drive your disconnect contactor through some fairly simple circuitry.

There may be better / cheaper off the shelf options available nowadays, it's a while since I looked at it.
For a total belt and braces solution you could put in place a secondary LV/HV disconnect monitoring system that looks at the overall pack voltage and operates slightly above / below the limits of the cell monitors.


Title: Re: New battery needed....
Post by: freddyuk on March 16, 2016, 03:07:37 AM
Consider AHI Aquion. No drama they just work. If you have floor space (30 x 30cm per stack) you can fit and forget. Work well with Victron and will latch onto your existing PV installation and take any spare power for charging. If no dump load facility the Victron can throttle back power of the PV. Nothing greener out there to my knowledge. With 100% DOD potential you only need 50% of FLA capacity so numbers stack up.


Title: Re: New battery needed....
Post by: readiescards on March 16, 2016, 06:18:22 AM
From my limited research the Aquion has higher internal resistance so leading to much reduced maximum output current and likewise longer charge times.  Meaning you need more than double the capacity of the lead acid to achieve the same kWp/h, along with the need to run the generator, or have the sun available, for longer.

Given they are already jolly expensive (along with I suspect zero scrap value), they need to fall in price significantly to be a true competitor to the alternatives.




Title: Re: New battery needed....
Post by: Fionn on March 16, 2016, 08:27:23 AM
To be fair, the leaf cells "just work" too.
I have a 4 module pack that I've been using myself for over a year.

They're a really conveninent form factor and there are plenty of comprehensive BMS systems on the market that could be used with them.
They can be charged at about 2C and discharged at at least 4C too, so ideal for high powered inputs like wind or generators.


Title: Re: New battery needed....
Post by: MR GUS on March 16, 2016, 09:17:56 AM
Fionn, any threads i've missed regards your leaf batteries, till off-piste gets back off his leaf battery assisted yacht / cruiser trip (no joke) I think you may be lead person for any battery pack high jinks!  :)


Title: Re: New battery needed....
Post by: Fionn on March 16, 2016, 09:42:32 AM
Hi Gus,
           I only have 4 modules that I picked up from a seller in the states some time ago.
I haven't shared much on them. Ideally I would get 3 more modules and make it into a 48V system, it would be more useful for me then.

Just this morning a pack from a 2011 car was listed on eBay UK for 1500, no detail on mileage though.
More and more should become available over the coming years.
As early cars are crashed, even light damage will make repair uneconmic with the residual value of the battery packs.


Title: Re: New battery needed....
Post by: nowty on March 16, 2016, 09:46:38 AM
Jonah how old are your fecked batteries ?

I am interested how long they lasted with your said abuse.


Title: Re: New battery needed....
Post by: Jonah on March 16, 2016, 11:15:34 AM
Thanks all, I really want to go the leaf battery route but just a bit scared on the second hand bit although not as scared as the price of new...

I was looking at some leaf batteries in Norway which I'd be happy to drive and get although if I could get a cheap set here and they are easy enough to work with id go for that.

Fionn, where are the first batteries you mentioned?

Nowty, in all fairness I cooked my batteries, they were excellent for two years then I moved house and didn't put them on my new place for another 18 months ish and just left the battery sat full but just abandoned and when I went back to it loads of cells were empty, sg levels all over the shop etc etc but it still works excellently in the longer days when it can have the solar all day but it take a lot more in than it give out. I did try getting some acid to add back in to see if I could fix things but that's as far as it went.

Thanks all


Marc


Title: Re: New battery needed....
Post by: Fionn on March 16, 2016, 11:24:58 AM
Hi Jonah,
               Sorry, I should have clarified, it's the same seller that has the 2014 pack for 2200.
He hasn't listed it directly but it's listed with the engine he has for sale item 281944970610.

I'm sure delivery on a pallet wouldn't be too expensive, I think the seller is in Latvia.
If you go that route I'd happily buy 3 modules from you (you'll have 6 left over if you go 48V).

I wouldn't be overly concerned about buying second hand so long as there is no mechanical damage to the pack.
The Nissan BMS is excellent obviously and there have only been 2 recorded Leaf battery failures in Europe to date AFAIK. Most likely even these would have been single module failures so wouldn't have a big impact on you as you could easily swap out a bad one for a spare.

Fionn.


Title: Re: New battery needed....
Post by: Jonah on March 16, 2016, 11:28:47 AM
Ok thanks, I did email these guys a few months ago about a set they had and have just emailed about the 1500 ones. What is the dod on them? Would I have to treat them like LA battery? Do they give off much heat? Should they go inside building or outside?

Thanks again.

Marc


Title: Re: New battery needed....
Post by: Fionn on March 16, 2016, 11:37:09 AM
Hi Marc,
            In the leaf I think the usable portion is about 21kWh so a DOD of about 87%.
In 48V configuration with 42 modules you'd be down to about 22kWh anyway.
If it's enough for your needs I would set them up for about 15kWh of usable capacity, clipping the top and bottom 15% of the charge cycle.
You can keep them where you like, I'd keep them indoors, about 15C would be a good temperature to keep them for lifetime and performance.
They will give out next no no heat at the typical charge and discharge rates of a stationary storage application.
In the car they can be charged at 22kW and discharged at 90kW, they will have a very easy life with you compared with their original use.
Fionn.


Title: Re: New battery needed....
Post by: Jonah on March 16, 2016, 11:42:52 AM
I think you've sold the idea to me there fionn...  Size wise that's fine, I have one of the Victron set up to dump to an immersion heater at the moment and the other one has a grid tie so it doesn't matter if we don't have enough capacity as it just knocks over to the mains, it's all just a bit of fun to me.


Title: Re: New battery needed....
Post by: Fionn on March 16, 2016, 12:04:29 PM
Cool, I'm not selling anything mind!
Just that the Leaf cells are the best value storage available to my knowledge at the moment.

If you use them as I described in the middle of their discharge cycle, they should last in the ballpark of 5000 cycles I suspect.
They are also super efficient at charge and discharge and very very easy to use once you put a BMS in place and set up proper disconnects for low and high voltage.
Ideally these should never operate as diversions loads should come on before the high limit and an alternative input (generator, grid or whatever) should come in before the low limit.

A benefit of their high speed charging capability is that the voltage is very stable meaning that you can do the above within fine voltage margins.
For example if you were taking in wind input which can have short lived high power bursts. If you tried the same with lead acid, the dump load would be cutting in as battery voltage would spike a lot more due to the higher internal resistance of LA. The lithiums would just soak up the incoming current and store it away, reducing wear on the active components.

LG Chem make 48V blocks now that a company I deal with uses. They are warrantied for 10000 cycles within their specified discharge range, they have onboard data logging to monitor usage.
You also don't need to worry about venting and hydrogen explosions and the like!


Title: Re: New battery needed....
Post by: Jonah on March 16, 2016, 01:53:19 PM
Thanks, I suppose I'm just a bit scared as they are expensive and can go bang... I presume they are just like normal 2v cells to work with after stripping the Nissan box apart? Just positive and negative and string them as required? Do the cells get monitored individually or in stings? Sorry if you've already answered these but I'm a bit slow lol...


Title: Re: New battery needed....
Post by: Fionn on March 16, 2016, 02:23:40 PM
They are lithium cells so they're max 4.2V a cell.
The module consist of 4 cells, 2 in series, 2 in paralllel, so the max voltage per module is 8.4V.
There are 3 terminals on each module, 0V, 4.2V and 8.4V.
The centre tap is only for cell monitoring, it's not designed for taking off load. You need to monitor each individual cell.
This is easy as you can reuse the nissan wiring and connecting hardware.
Photo of some of the bare modules:
https://i.ytimg.com/vi/NrCiQRmGui0/maxresdefault.jpg

There are lots of tear down videos of the full modules on Youtube.

If you buy a complete battery you'll need to be extremely careful when disassembling as the pack is configured for high voltage use in the car.
Once you get them broken up and configured for 48V operation they are far safer as the shock risk is largely eliminated.

In operation, you'll need to make sure that the whole setup is fused correctly and avoid shorts at all costs but this is no different to any bank really.





Title: Re: New battery needed....
Post by: MR GUS on March 16, 2016, 03:11:58 PM
Fionn, do you remember the off-piste thread? wondering if you've used any of the set up / monitoring software he incorporated.

Waiting for my wee pay-out (dragging on) to view, load & drive off with a pack of leaf batts what is the checking & dissassembly process? (ie protocols, cos there's obviously no comeback after the sale & some distance between the vendor).

what test kit? take my garage mechanic on a jaunt?

what have you learnt & what has your insurance company said?

I'll hoover up any info you care to impart, cheers  :crossed


Title: Re: New battery needed....
Post by: Fionn on March 16, 2016, 03:49:48 PM
Hi Gus,
          Been a while since I read the off-piste thread, but if I recall he used a good off the shelf BMS which cost about 1000.
He looked to have done a fine job, and using a 19in rack to house the modules was a good idea.

Not much to check for other than mechanical damage if you buy one.
If the car is operating you can invest in a cheap bluetooth dongle and the "Leaf Spy" app for android phones, this will give you extensive detail on the history of the battery, number of cycles, number of fast charges, remaining capacity etc.
I've read that there were significant improvements to the battery chemistry in late 2013, not sure if they're that significant for our application but they supposedly reduce degradation in automotive use.
The mileage on the car will give you a good overall indicator if you don't go to the above bother.

As regards insurance, I'm not sure what you mean - impact on home insurance?
There shouldn't be an issue as they are an automotive battery, the company i dealt with that uses the LG packs now used a few before because they were far easier to ship than other lithiums since they were an automotive component.


Title: Re: New battery needed....
Post by: Jonah on March 16, 2016, 04:53:52 PM
The only battery that company has left is a 2011 with 26000 miles, does anybody know any sort of mileage life span?

Thanks

Marc


Title: Re: New battery needed....
Post by: phoooby on March 16, 2016, 05:13:29 PM
I think the warranty on 2011 car is 5 years 50k miles. Average 4 miles per kwh gives 6000kwh to get from 26k miles to 50k miles (ie. 6000kWh needed to travel 26,000 miles). That works out at roughly 250 cycles of a 24kWh battery. I'm only going on the warranty to give an idea, I don't for one minute think you could make a warranty claim having butchers the battery. I'm sure there are many Gen 1 cars about with mileage in excess of 50k that are still doing fine. Also you have to consider that using the middle band as suggested above will extend life and you are never going to be charging at 50kw or discharging at 80kw as in a car application.

The newer chemistry on Gen 2 cars seems a big improvement. There is a taxi with 140k miles on the clock still going strong having only lost a single capacity bar on the dashboard.


Title: Re: New battery needed....
Post by: MR GUS on March 16, 2016, 05:53:44 PM
Spot on Fionn, yes house insurance.

Leaf spy! ..will check that out.

 think you'll have to be the forum pimp-daddy for leaf battery shenanigans from this point on!


Title: Re: New battery needed....
Post by: Jonah on March 16, 2016, 08:32:24 PM
Thank phoooby


Title: Re: New battery needed....
Post by: Fionn on March 16, 2016, 08:56:23 PM
Certainly you can forget about the warranty once you remove the battery from the car.

Happy to answer any questions Marc but I'm no expert, only done a little tinkering.

Phooby is spot on with regards to the Gen 2 batteries, I've read the same.
And again regarding lifespan, they're doing well in the cars, they should do far far better as stationary batteries.

I think the 2011 battery is probably still good value at that price for the year and mileage, I'd probably take a chance on it myself if I had a need for it.

On the insurance, best to check with your insurer or broker, I don't know anything about insurance really.
I like to self insure through good engineering in so far possible, install in such a way that it's virtually impossible to cause a fire!


Title: Re: New battery needed....
Post by: Jonah on March 16, 2016, 09:35:46 PM
Thanks guys n girls, I appreciate all your help and advise.

Thanks

Marc


Title: Re: New battery needed....
Post by: freddyuk on March 23, 2016, 06:25:25 AM
From my limited research the Aquion has higher internal resistance so leading to much reduced maximum output current and likewise longer charge times.  Meaning you need more than double the capacity of the lead acid to achieve the same kWp/h, along with the need to run the generator, or have the sun available, for longer.

Given they are already jolly expensive (along with I suspect zero scrap value), they need to fall in price significantly to be a true competitor to the alternatives.




This is from the operation manual:
The AHI chemistry can be rapidly charged such that more than 90% of the nameplate (20-hour) capacity can be input into the battery in approximately 4 hours. This is accomplished by using IR-compensated charging, which permits the allowable Vmax to exceed the specified (non-IR-corrected) Vmax, and setting the charge current to the highest allowable value (13 A for S20 Battery Stacks). Under these conditions, the IR-corrected Vmax becomes approximately 66 V (for an 8-Stack configuration). When this IR-corrected Vmax is reached during charging, the current applied to the Stack should be reduced, and Vmax should be lowered in concert during the current taper phase of the charge. Cycle life testing using this charge regime indicates that this is a safe and reliable use case, and we do not expect any unusual loss in function as a result of fast charging.........

Also the price of this technology is commercially pegged to the Lithium price but the actual raw materials cost is such that the price margin options are there and not subject to possible feedstock issues resulting from potential lack of or control of supply from the limited resources as with Lithium which I suspect could force up the price dramatically.

Each battery unit is already 48volts so easy to connect to existing inverter chargers without any additional components.

As regards safety - this is an excerpt from the LG Chem Lithium manual:

4 Emergency Situations
The RESU 6.4 EX battery pack comprises multiple batteries that are designed to
prevent hazards resulting from failures. However, LG Chem cannot guarantee
their absolute safety.
4.1 Leaking Batteries
If the battery pack leaks electrolyte, avoid contact with the leaking liquid or
gas. If one is exposed to the leaked substance, immediately perform the actions
described below.
Inhalation: Evacuate the contaminated area, and seek medical attention.
Contact with eyes: Rinse eyes with flowing water for 15 minutes, and seek
medical attention.
Contact with skin: Wash the affected area thoroughly with soap and water,
and seek medical attention.
Ingestion: Induce vomiting, and seek medical attention.
4.2 Fire
In case of fires, make sure that the following equipment is available near the
battery pack.
SCBA (self-contained breathing apparatus) and protective gear in compliance
with the Directive on Personal Protective Equipment 89/686/EEC
Novec 1230, FM-200, or dioxide extinguisher.
NOTE
ABC extinguishers are not effective when the battery pack is on fire.
Batteries may explode when heated above 150C. If possible, move the battery
pack to a safe area before it catches fire.
11
Emergency Situations
4.3 Wet Batteries
If the battery pack is wet or submerged in water, do not let people access it,
and then contact LG Chem or an authorized dealer for technical support.
4.4 Damaged Batteries
Damaged batteries are dangerous and must be handled with the utmost care.
They are not fit for use and may pose a danger to people or property.
If the battery pack seems to be damaged, pack it in its original container, and
then return it to LG Chem or an authorized dealer.
NOTE
Damaged batteries may leak electrolyte or produce flammable gas. If such
a damage occurs, immediately contact LG Chem at +82-43-219-2720.
12


Aquion are completely safe without any notifiable hazards. So if the price per kWh was the same would that make them a better choice for the domestic environment?
Being non toxic they are easy to recycle but not for a financial reward or potential hazardous waste cost.