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Author Topic: Do lithium batteries make sense for off-grid?  (Read 11627 times)
wookey
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« on: January 04, 2010, 12:21:48 AM »

Just reading Elanor's thread about which batts to buy. It occurred to me that no-one uses anything but variations on the lead-acid theme in off-grid world, but seeing the prices for her 24V 1000Ah system (2200 - 3300, and that's the cheap-and cheerful end), I wondered if the new lithium chemistries made any sense in this application? They are taking the electric vehicle world by storm at the moment and thus come in big-enough sizes. They are quite a lot more expensive than lead-acid, but in EV applications (fast/deep discharge and recharge) last about 6 times as long. I don't have a good handle on the usage profile for off-grid. What sort of discharge rates and depth profiles occur? Is the 1000Ah because that capcity is needed, or because this oversizing prevents deep-discharge and keeps C-rates low?

A 24V 1000Ah LiFEPO4 battery set would be 3750 from Foxx/Aten energy in the US (35 3.2V x 200Ah cells). That's before delivery and battery-management electronics which would add another few hundred quid. But that's only 'some' more expensive. If these cells lasted significantly longer, or their discharge rates were better, or the deep-discharge tolerance meant that in fact a smaller pack could be used, then that starts to look competitive. They can be fully discharged (until weakest cell hits 2.1V) often and will supply 3C continuous (thats 60kW on this pack - peaks of 100kW). You can expect 3000 discharges to 70% DOD and 2000-odd to 80% DOD. I have no figures for what happens if they are left to sit, mostly full.

Clearly one of the main advantages (~1/4 the weight) is largely irrelevant in this application. And I guess no-one really knows what the longevity of such cells is in the mostly-full off-grid application.

So, just an idea, but I wonder if we are getting to a point where lead-acid ceases to be such an obvious answer. I imagine for fork-lifts LiFePO4 is already sensible, but as observed above, that's a very different usage profile from off-grid storage.

Thoughts? Is this just crazy-talk? These batteries are due to get a lot cheaper over the next few years due to EV use. And there is plenty of competetion.
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Wookey
pipesmokingman
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« Reply #1 on: January 04, 2010, 05:12:05 AM »

get cheaper ?? - you may wish to peruse this  : http://blogs.wsj.com/environmentalcapital/2009/02/03/peak-lithium-will-supply-fears-drive-alternative-batteries/

lead acid type batteries are not getting cheaper that's for sure - every time i have to replace my scooter batteries its a sharp intake of breath  fume

and certainly for low use applications it has proven there is no sense in recycling them - better to bung them in the battery bank - and keep going - I have nearly 10 year old traction batteries that are STILL doing good service - take charge fully - and hold it !! - and do me for what i need ( mostly lighting and low power stuff and will run an inverter quite happily if needed  ) - OK the experts will cringe at such statements , but so far it works for me !!

and in stand by / low draw applications costs me nothing extra - OK it wont run the whole house - but it does save something - and something is better than nothing eh ??

now some will say but if they take and hold charge ,why not use them for the scoot ?? - well it would appear that its all a question of current draw ( I'm no expert on batts ) - the scoot CAN potentially draw any where up to over 100 amps in stall high load condition ( cutouts at 70 amps ) - and prolonged draw of even 40 amps soon tells the tale - BUT  if you are ONLY really drawing peanuts power out of them - say 10 amp max  then they are fine ( again for what i want them for )

what ever - i digress - simple fact is its will be the old supply and demand scenario -  of course as oil declines then the politicos will be looking to tax alternatives - and also he who holds the materials calls the shots  the oil producers have proven that - add in the speculators etc ,and frankly i don't see prices coming down any time soon - going up may be but down ?? - nah
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Billy
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« Reply #2 on: January 04, 2010, 08:08:26 AM »

Big banks cost a lot of dosh, I reckon people are not going to take a punt on untried (in off grid) stuff.  NiCads are  brilliant, you can flatten them and change the electrolyte but how many people use them?  They need a different charge to make them work properly and it seems very few make gear adaptable for them.  Wouldn't it be rather nice to get rid of those monsters with the drink problem and the worry of them blowing up if they get angry or upset.

Billy


 Grin Grin Grin
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EccentricAnomaly
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« Reply #3 on: January 04, 2010, 10:14:41 AM »

I wonder if off-gridders could give a good home to lithium EV batteries between the time they become a bit too tiered to use in a vehicle and the time they're only good for recycling.  That would depend on how they fail, of course.  Anybody know?
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Outtasight
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« Reply #4 on: January 09, 2010, 12:11:49 AM »

I expect there will be a market for used lithium traction packs.  In a vehicle you'll be asking it to deliver a couple hundred Amps and on a inverter you'll be looking at no more than 10-20A most of the time (even when I'm using the kettle it's only 30A at 24V).

I tried to get a quote from Valence for their U-Charge packs but they're only interested in selling to EV makers at the moment.  Bonkers when the U-Charge packs are made in Group24/27 sizes (100/138Ah) and advertised as perfect replacements for lead acid marine batteries - DOH!

http://www.valence.com/products/battery_modules

The Valence ones are a bit different, being LiFeMnPO4.  The Magnesium bit means that they have a very close voltage to lead acid (12.8V nominal) and can be charged using regular lead-acid type chargers (the BMS built into the pack handles balancing or high power ones have an external BMS).  So they are a drop-in replacement for charging with my Morningstar MPPT PV controllers.  The great benefit is that they can be run flat for thousands of cycles and left like that without instantly destroying themselves.  So you don't need such a large bank.  I've got 180Ah gel batts now but you can only really use 50% of it.  Gels will survive deeper discharges more often than flooded or AGM but they still hate being left like that for any length of time.

After Googling around a lot yesterday, I discovered that Optare are making a "Hopper" sized single deck electric passenger bus with Valence U-Charge XP U27-12 packs so in a few years you might start finding ex-bus packs floating around on the second hand market in the UK.  A Chinese maker called Shenzhen OCELL is making some U-Charge looky-likes but they are LiFePO4 types so need the provided special chargers.  Valence have exclusive patents on the Magnesium variant.

http://www.ocelltech.hk/Product_View.asp?id=59

But for a multi-million $ business, they can't get the button text on their web page to line up properly...  Roll Eyes

The main claim to fame of the Valence types is that they don't blow up at the slightest upset (over charging, over discharging, dropping them, looking at them in a funny way, shooting them with an automatic rifle)...  Yes, they did test them in a YouTube video by shooting them!

I did find a very old 2006 quote on the web for the Valence U27-12 packs but they were about $2500 then.  3k is a lot of dough for a 138Ah 24V bank... but then Sonnenschein 330Ah 6V packs are 500 each so a 330Ah 24V pack would cost 2k and you can only use 165Ah of it so maybe the Valence packs aren't so expensive after all.
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http://solarbodge.blogspot.com/
3.58kWp & 800Ah LiFeYPO4 off-grid(ish). See 'Cobbled together PV in W.Sussex' (in "Show Us Yours")
wookey
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« Reply #5 on: January 09, 2010, 01:42:14 AM »

Useful info there. Justto clarify. That's LiFeMgPO4 (ie magnesium, not manganese), the typo being potentially confusing because there is also a Lithium-ion managese chemistry. That valence chemistry is a new one on me - I think that makes 7 different lithium chemistries available now.

pipesmoker: The LiFePO4 batteries are certainly getting cheaper at the moment. I've seen 10Ah cells drop from $27 each to $14 each in about a year. Quite what will happen in the long term is not clear. Lithium is a lot more common than Lead, Nickel or various other elements, but it is hard to extract due to being very reactive. There isn't actually that much lithium in each battery and there are large accessible deposits in south america (currently being dickered over - the Bolivians are being very smart and only selling the right to set up native processing and battery production companies). I see no reason why prices won't continue to drop for a while.

Not sure what you are trying to say about recycling. Lead-acid batteries are the most recyled thing on the planet. Ah, I see. You are saying that old vehicle batts are still good for off-grid use. True, but once dead for that then they will eventually need recycling.

Eccentric - here is some excellent info on what goes wrong if lithium ion batteries are abused:
http://www.mpoweruk.com/lithium_failures.htm
Not entirely clear how much that is modified by the off-grid usage characteristic.
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Wookey
EccentricAnomaly
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« Reply #6 on: January 09, 2010, 10:59:39 AM »

So they are a drop-in replacement for charging with my Morningstar MPPT PV controllers.

Am I confused again?  I thought the Morningstar MPPT controller was just coming out and nobody had them yet.  Is it that they're doing a bigger MPPT now or something?
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EccentricAnomaly
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« Reply #7 on: January 09, 2010, 11:25:54 AM »

Eccentric - here is some excellent info on what goes wrong if lithium ion batteries are abused:

Thanks, indeed interesting.  One thing they're not clear on, though, is storage vs operating temperature ranges.  They say you shouldn't operate the cell below 10 or 15C.  As I understand it, car cells actually warm themselves up if you do operate them at lower temperatures so I assume it's OK to store them at lower temperatures.  Perhaps before leaving a few thousand pounds worth of cells at home it would be worth being clear about this.

Also, that page is about abuse of the cells.  From the donkey sanctuary point of view I wonder what happens to a pack of lithium cells towards the end of its normal life, assuming the battery management system has prevented abuse.  Does one cell fail completely or do they all decline slowly?  Is there scope for bypassing a cell and re-flashing the BMS to allow for it or otherwise fiddling with the BMS parameters to make good use of the pack for a while.  All very speculative but something to bear in mind for the long term.

Wookey's first post:
Quote
I have no figures for what happens if they are left to sit, mostly full.

More recently:
Quote
Not entirely clear how much that is modified by the off-grid usage characteristic.

It's also worth bearing in mind that the present "off-grid usage characteristic" is somewhat biased to fit the properties of lead-acid.  As you've already pointed out, limiting the DOD is battery chemistry specific so a smaller capacity may be appropriate for cells which can be more deeply discharged.  In addition, the habit of keeping the batteries as full as possible is also brought on by chemistry specific fears (of sulphating).  If the battery will sit happily at, say, 50% DOD then maybe it makes sense to do that more often in order to increase the capacity available when the sun shines or the wind blows.
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Outtasight
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« Reply #8 on: January 09, 2010, 01:15:05 PM »

Yep, My bad... It is Magnesium not Manganese.

I've got a pair of the 15A Sunsaver MPPT controllers.  The MPPT versions of the Tristar controllers are the ones that nobody has yet.

I'm of a mind to give up waiting as it would be cheaper to just get a third Sunsaver, which would give me 45A of charge control but with the flexibility of having three MPPT trackers for different parts of my array.  It also means I could charge three separate battery banks at either 12V or 24V but I've currently got the paralleled into one bank.
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http://solarbodge.blogspot.com/
3.58kWp & 800Ah LiFeYPO4 off-grid(ish). See 'Cobbled together PV in W.Sussex' (in "Show Us Yours")
Outtasight
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« Reply #9 on: January 09, 2010, 06:37:40 PM »

A 24V 1000Ah LiFEPO4 battery set would be 3750 from Foxx/Aten energy in the US (35 3.2V x 200Ah cells).


Found this about the Foxx/Aten batts...

http://goldenmotor.com/SMF/index.php?topic=98.0

Are these batts for real?  The web site I found for Aten looks very "home made" and hasn't been updated in a couple of years.

http://www.atenenergy.biz/Foxx.htm
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http://solarbodge.blogspot.com/
3.58kWp & 800Ah LiFeYPO4 off-grid(ish). See 'Cobbled together PV in W.Sussex' (in "Show Us Yours")
wookey
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« Reply #10 on: January 10, 2010, 01:29:38 AM »

I'm pretty sure they exist now. That thread was 2 years ago. He quoted me about 3 weeks ago. Expensive shipping from the US ($225) contributed to me picking Headway in the end. You can buy them from his ebay shop: http://stores.shop.ebay.co.uk/Foxx-Power-Lithium-Batteries__W0QQ_armrsZ1   Here are a couple from people who actually have them:
http://endless-sphere.com/forums/viewtopic.php?f=14&t=8600&p=140230&hilit=foxx+cells#p140230
http://endless-sphere.com/forums/viewtopic.php?f=3&t=6524&p=98305&hilit=foxx+cells#p98305

Eccentric, as you say, the 'mostly full' thing is really a lead-acid side-effect. Laptop lithium-ions (lithium cobalt oxide normally) like to be stored cold at about 40-60% charge. That minimises self-discharge. Not sure if it also affects overall lifetime.
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Wookey
pipesmokingman
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« Reply #11 on: January 10, 2010, 06:04:56 AM »

I wonder if off-gridders could give a good home to lithium EV batteries between the time they become a bit too tiered to use in a vehicle and the time they're only good for recycling.  That would depend on how they fail, of course.  Anybody know?

does anyone read my posts round here Huh  Huh - what holds true for my scoot batteries will hold true for these things -BUT - if you SERIOUSLY think you are going to get any used ones - think again - there will be soo many regs about recycling by then - and lets be fair a certain scrap value - they will be like hens teeth - i ONLY get scoot batteries because i purchased em in the first place - if i go to the battery place they want to keep the old ones and get mighty weasel peed off when i refuse - which is WHY i just get a taxi to collect them ( providing i can FIND a taxi firm that will transport them - bloody H&S rules ) - if not trailer on scoot and pray i will get back

rule one of life : there is NO  such thing as a free ( or reduced price lunch )

rule 2 : if someone can see a way of making a buck from scrap - they will

rule 3 - no one gives stuff away if it has monetary value

rule 4 - take what you can - give nothing back !!

ho hum - stick to lead acid /gel /agm - forget any cast off lithium for a long while yet  Wink
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EccentricAnomaly
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« Reply #12 on: January 10, 2010, 10:45:12 AM »

Yes, recycling rules might be a problem - it's the sort of thing to watch out for and campaign against (not recycling rules in general, just rules that are so draconian that making sensible reuse of a resource is prevented).

I don't think anybody has suggested they would likely be available for free.  They might, however, have more value for use for a few years than would as immediate scrap - given that the use won't make the scrap value go away. 
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Outtasight
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« Reply #13 on: January 10, 2010, 01:51:19 PM »

rule one of life : there is NO  such thing as a free ( or reduced price lunch )

rule 2 : if someone can see a way of making a buck from scrap - they will

rule 3 - no one gives stuff away if it has monetary value

rule 4 - take what you can - give nothing back !!

ho hum - stick to lead acid /gel /agm - forget any cast off lithium for a long while yet  Wink

Yeah, I don't think we expect to find any free EV batts (although it couldn't hurt to move to somewhere near the Optare factory and find out which pubs the garage crew frequent  whistlie).  Telecoms companies and fork lift outfits are getting round the waste disposal issues of old lead batteries by selling them to off-gridders on eBay.  You don't need a waste disposal certificate if you are selling them on to another user... They haven't become "waste" yet.  The definition of a "spent" lead-acid battery for manufacturers and companies that use them is when its capacity has fallen to 80% of new.  Even 50% of 800Ah is still useful to someone - just not a fork lift that has to operate for 6-8 hours between charges.

I got given a load of used 7Ah SLA packs for free by a guy I bought a cheap second hand solar panel from.  They seem ok (used a couple to replace a dead pair in my UPS) and sold some at a car boot for 4 each... Free lunch  Grin

With the Optare bus, they're using a large number of blocks per bus and the general rule is that you have to replace a pack as a whole if it's been in service for a while so in a couple of years there's bound to be some buses that have had a block go bad in the pack and they bin the whole pack because you can't replace the failed one with a new one as then it will be too new compared to the 2 year old ones left.  They could try to keep a stock of used blocks of different ages to find one that is suitable but then that's a lot of old batteries to be keeping around.  They'll be on a warranty contract with the battery / EV supplier so they'll actually get the whole set replaced on warranty and the part packs will either get recycled (for the raw materials only) or binned (or disposed of by the same guys on eBay who sell partial fork lift packs now).

I know of some EV buses that had a bad batch of cheap Chinese gel packs and have binned a few and replaced them all with much more expensive (but reliable) Sonnenschein Dryfit ones.  The dodgy partial packs are probably sitting in a warehouse yard somewhere waiting to be sold off cheap to caravan owners as we speak.

I note that some of the LiFePO4 web sites state a benefit of the tech is that there are no heavy metals or other dangerous (and therefore expensive to dispose of or recycle) elements used so the natural conclusion is that they are cheap to dispose of (as land fill-safe garbage!!! ).

Data centres replace their UPS batteries on a fixed schedule to be on the safe side, regardless of the state of the batteries. Usually its well before the end life of of the batteries because the cost of a battery bank is insignificant to the cost of a power failure in the data centre, so batteries with a useful life are always turning up cheap on the used market.

The recession means that lots of neat kit has been turning up at car boot sales /eBay as companies go bust and they or the administrators flog off whatever they can.  I got the 17" LCD monitor I'm using now at a boot sale from a company that went bust for 15. Even corporations sell at car boots.  I often see seconds and left over stock selling from white vans that's come from Maplins and Argos.  The chains just sell the stuff to these white van men for peanuts (it might be broken or customer returns or just old stock or in a damaged box... all reasons for it to not be sold in store) and they sell it for whatever they can get for it.  I got a 1.5kW oil radiator for 4 and some shelving for 1.

There's ALWAYS stuff to be had for next to nothing... You just need to look in the right skips  Grin  Parts of my PV system are held down / up / together with the contents of my next door neighbour's skip from his kitchen extension.

I think municipal dumps should be converted to a mechanical & electric engineers charity shop!

Rule 3 - It's amazing what people throw away rather than give/sell.

 bike
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http://solarbodge.blogspot.com/
3.58kWp & 800Ah LiFeYPO4 off-grid(ish). See 'Cobbled together PV in W.Sussex' (in "Show Us Yours")
Outtasight
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« Reply #14 on: February 26, 2010, 11:33:54 PM »

Some more lithium battery info.  I found a UK distributor that seems to be willing to sell packs to ordinary folk rather than just EV makers.

Quote
Thank you for your enquiry about the use of LiFeBATT a Lithium Iron Phosphate system in your solar application. I can advise that our LiFePO4 solution would fit well into your application with minimal modifications. We would recommend 2x XPS2E 024045 modules giving 26.4V and 90Ah, maximum discharge for this combination would be 270A constant with peak currents of 300A for 20 seconds.

As for charging, it requires a maximum voltage of 29.2V and with high discharge currents we recommend the external Battery Protection Module. This links with the internal voltage management system (VMS) for complete battery protection. The VMS controls the cell balancing during charge and discharge, monitoring of cell voltages and temperature, recording cycle count and error count. It provides this data to the Battery Protection Module through a RS232 link. 

The modules can provide full capacity to 100% depth of discharge and a life of 2,000 cycles to 80% of the original capacity. So a 90Ah system will still yield 72Ah of usable capacity after 2,000 cycles.

Check 'em out... http://www.lifebatt.co.uk
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http://solarbodge.blogspot.com/
3.58kWp & 800Ah LiFeYPO4 off-grid(ish). See 'Cobbled together PV in W.Sussex' (in "Show Us Yours")
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