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rachelsdad
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# Posted: 2 Dec 2022 04:41am
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https://www.ebay.com/itm/325446453899?hash=item4bc61eca8b:g:KcYAAOSwtJxjPmwo
Anyone have any experience with these?
Almost seems to good to be true on a $ per kwh basis.
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Steve_S
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# Posted: 2 Dec 2022 10:13am
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They can work but that particular chemistry is problematic for solar gear including inverters. These are 18650 Li-Ion cells (NMC or NCA I forget which) and their power curve is a bugger. Also these are the cells that can runaway & catch fire.
These would still require a BMS & Harness, choosing a Solar Controller & Inverter system that can be configured/programmed to use the voltages etc...
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rachelsdad
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# Posted: 2 Dec 2022 01:58pm
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Thanks Steve,
I had a trouble free year with the Volts after I left the last bank on for a few weeks with the CC off, (they bulged like Nobadays).
In fact I had already purchased two more to up my storage but it seems like the original opinion on these may not have been as rosey as I was led to believe. So I guess I'm searching for alternatives for my 24 volt system.
Can't seem to find much info on the Volts any more on line, (like you could when they were becoming available in numbers), and like you stated in the past, 8 years, (age of my batteries), has passed and technology has improved.
I dunno....if you think they are still worth using for the next few years I'd keep 'em as I do love the size and quick charge in the mornings.
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Steve_S
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# Posted: 3 Dec 2022 07:46am
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My concern would be WHY did they bulge, especially when no power was being sent into them. That just isn't right and NCM/NCA are quite stable at various "ambient" temperatures.
For an ESS system my only recommendations are to look at LFP (LiFePo4) battery packs and not only because they are the safest of the Lithium Base family but also because they present very similar voltage profiles as Lead Batteries. That makes them far easier to integrate with Solar Related Gear. LFP charges pretty fast as well but I don't know of any speed comparison for charging the different Lithium based chemistries.
Many companies making battery assemblies for Energy Storage Systems are already using LFP or are in process of switching to LFP from other Li-based chemistries. And the number of companies diving into the segment is increasing exponentially, it's incredible to see, actually.
I cannot make any suggestions with regards to the Volt Car Battery packs and whether to keep'em or not, that's your call as it is your risk & liability and your investment in them.
Just note, that LFP batteries have their own voltage curves and they are not that close to other Li Chemistries so they can't really live side X side with other chemistries. Some manage to get LFP & FLA to coexist but that is even difficult (I know, did it for 2 years). I disposed of my 8 Rolls Surette Batteries this summer ($2800 worth of batteries which hurt).
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Nobadays
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# Posted: 3 Dec 2022 09:58am - Edited by: Nobadays
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Quoting: rachelsdad I dunno....if you think they are still worth using for the next few years I'd keep 'em as I do love the size and quick charge in the mornings.
If you have them and they are still working, why change them out?
As you know I lost 8 modules last spring from swelled pouches. It is gas production within the pouches that causes swelling. From what I read there are several factors that can cause this to happen, chiefly, over charging, high temperatures, rapid discharge and over discharging. I am pretty well convinced mine was a case of over discharge. Though everything was turned off, the modules were still connected to the inverter as I had not shut those breakers off. The Schneider Conext 4048, from my understanding, when turned off has no parasitic draw, however, I'm not convinced. Each module, even though some were swollen to the extreme still had 20v in them, all of them. If it would have been a failure of one or two module (i.e. the newest ones I added) I believe I would have seen a significantly different voltage reading on one or two modules. What I saw was a consistent and equal drain on all 8 modules. I have to conclude, operator error. I should have turned the main breakers off that feed the inverter as I had in past years (3am locking up the cabin... brain fuzzy! I forgot.)
Edit: The BMS is supposed to prevent this from happening, I had no BMS, just the balancer, which was unhooked... so it was not keeping the cells equal while not in use.
Would I buy and use Chevy Volt modules again? No I'm loving my new LiFePo4, but if mine were still good I would still be using them.
My two cents !
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Steve_S
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# Posted: 3 Dec 2022 10:24am
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Ahhh the QNBBM Balancers are a tricky bit of gear, if the battery pack is not in use it is best to turn them off because they will keep drawing & transferring power even in small amounts. Now QNBBM does not make that easy... I was using Chargery BMS8T's with the 300A DCC's (Solid State Contactors) and QNBBM-8 active balancers with my first set's of LFP but I retired them all and replaced with JKBMS with built-in 2A active Balancing which works a treat.
Geez,, I am gonna have to make a big list of surplus gear, new & unused to gently used and have a Fire Sale to send it all to good homes.
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rachelsdad
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# Posted: 5 Dec 2022 08:26am - Edited by: rachelsdad
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Why change? Just looking for a better or "safer" option I guess.
I like to sleep at night and after reading your story, and Steve_S's responses, especially after yours heated up and popped after disconnect, (mine did not), I have that little cloud over my head. There was no huge change in temps, so I have to assume as well that they discharged, (I did turn off the CC, (WHY???), but may not have turned off the inverter.
My harness I purchased from Creeky...is he still in business?...can accommodate the additional two cells.
So I would be ok to keep using them, although I would lie recommendation for a better BMS.
Also...any help with recent info on Chevy Volt batteries?
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Steve_S
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# Posted: 5 Dec 2022 09:52am
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Unfortunately, I can't help you with Creeky's setups etc and I don't think he is about anymore....
I assume you are probably in Ontario if you bought stuff from Creeky.
All I could do for you, is to provide you with a couple of complete Chargery BMS8T-300's (24V 8S BMS) with DCC-300A Contactors and accompanying QNBBM-8S Active Balancers. I'd say $150 for a full set + shipping, or meet up somewhere like Renfrew or maybe Arnprior BUT not much further as I now drive a Ram 1500 SLT 4x4 and it guzzles badly.
BMS8T: https://www.chargery.com/BMS8T.asp
QNBBM-8S: https://www.aliexpress.com/item/32696417844.html
I am now using JKBMS's with built-in Active Balancers, BlueTooth & RS485 but they are having support quirk/issues ATM.
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Nobadays
Member
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# Posted: 5 Dec 2022 09:55am
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Quoting: rachelsdad especially after yours heated up and popped after disconnect,
Mine did not heat up, they were stone cold. They did.... seem... to continue to expand after removed but, they were inside 3/4" plywood boxes that prevented them from expanding until they pushed the screws out. When I disassembled the boxes they then "let go" and expanded to accommodate the swelled pouches. I had them on dirt, 4'-5' apart for nearly two weeks and checked them most every day. They never heated or lost anymore voltage. Pretty sure it was a case of over discharge and not a thermal runaway.
I appreciate you concern though. I was under the impression that lifepo4 was a very safe lithium chemistry compared to NMC. A little research leads me to understand now that lifepo4 is only "slightly" safer. All lithium modules regardless of the chemistry have the potential for thermal runaway. Electrical, mechanical or thermal abuse can initiate a thermal runaway on any lithium module.
But, the bad thing about repurposing lithium modules from the automotive industry is they do not come with a BMS. In the case of the Chevy Volt modules I guess I never did figure out if a BMS could be adapted to them. The balancer, yes but it offers no protection for over charging or over discharge. If my (likely your) modules would have had a BMS we wouldn't be having this discussion. Electrical abuse, i.e. over charging or extremely rapid discharge could potentially cause a thermal runaway, this is the scary part for me. A failure in the SCC could allow over charge, a short somewhere could cause a rapid discharge and with no BMS the potential is high for catastrophe.
If there is anyway to put a BMS on the Chevy Volt modules I would encourage you to do so. If not, then follow your instincts. If you can accept the risks use them. If not, change them out.
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Nobadays
Member
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# Posted: 5 Dec 2022 09:58am
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Good on you Steve! Will the BMS plug into the existing multi-pin plug on the modules? If so that would be brilliant! Peace of mind!
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Steve_S
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# Posted: 5 Dec 2022 10:21am - Edited by: Steve_S
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An adapter of some sort would be required or a customized harness... I dunno, never dealt with Motive Batteries, I built my own LFP Packs using EVE Cells.
I used Molex terminal strips with the BMS8T & Active balancers wired to one side and the other side to the battery cells.
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Nobadays
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# Posted: 5 Dec 2022 11:43am
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Quoting: Steve_S An adapter of some sort would be required or a customized harness... I dunno, never dealt with Motive Batteries, I built my own LFP Packs using EVE Cells.
Yeah that was my hangup, just not smart enough, or actually just don't understand enough to know how to wire a BMS in to the existing plug. The harnesses Creeky made could probably be adapted to the BMS, but I wouldn't know how.
This is the balancer and harnesses...
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Nobadays
Member
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# Posted: 5 Dec 2022 11:48am - Edited by: Nobadays
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Here... big end to modules, little end to balancer
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Steve_S
Member
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# Posted: 5 Dec 2022 02:06pm
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That doesn't help me much actually. It's a 12S Balancer setup using two 6s Balancers connected to a 12S Balance Board. The yellow harness' I haven't a clue how that's setup.
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Nobadays
Member
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# Posted: 5 Dec 2022 03:26pm
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Well I was hoping it would klick.... if "rachelsdad" wants to continue using the Chevy Volt modules it would be nice if he could add a BMS. I'm sure he has a similar balancer and harnesses.
I'll stick with my Chins with an internal BMS, really happy with their performance.
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Ontario lakeside
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# Posted: 8 Dec 2022 09:06pm
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We use a VOLT pack with a Chargery BMS, provided by Creeky.
It all worked well for years. We had an issue one time when I left the batteries in cold weather. I had unplugged and turned off all power draws except the BMS. This should have been fine as it was setup to balance in charge and discharge only. The battery was discharged well below 2 volts when I caught it.
It has not bulged at all, and is still in use. I manually top balanced it with a variable power supply and it has been behaving.
I believe the BMS is not up to the task and the interface / documentation is terrible.
The battery would balance to between 10mv and 80mv depending on state of charge before the low voltage incident. now it hovers around 100mv fully charged and 400mv at 41volts.
I have been using it between 48 and 42 volts to minimize balance issues.
I have lost some confidence with it and I'm thinking of getting a new 48 volt pack from a battery manufacturer.
Do you guys know if the wiring is the same for a active balancer as a BMS? I would like to give a active balancer a try if I can just plug it in!
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