Is 36% SOH too low for a gen 1 Leaf battery?

[neilnz]

Apologies if this has been broached in another thread, I couldn't find anything specifically.

I've been offered a complete 24KWh gen 1 pack for a reasonable price, but it's at 36% SOH. I know nothing much more about its life than that, but it's from a 2011 so it's old.

Is it likely to give reasonable service of ~8KWh for any amount of time in a low-load off-grid setup, or is there an accelerated decline at this sort of point in its life? I see most people building with 50-65% SOH modules.

I'm happy to test the individual modules and pick out the ones with the best IR and capacity, if that makes any difference.

 

[Solar Guppy]

Gen 1 leaf batteries had problems from day 1, I would say move on, nothing there is worth the time or effort.

 

[JRH]

Gen 1 leaf batteries had problems from day 1, I would say move on, nothing there is worth the time or effort.

What is a SOH…that’s a new term to me…???

 

[neilnz]

"State of Health". A polite way for a car/leafspy to tell someone how much life its battery has left. As I understand it, you can basically take it as a percentage of the rated capacity of the pack when it was new, so a 36% SOH 24KWh leaf battery pack has ~8.64Kwh of usable capacity, plus probably other unwanted problems like higher internal resistance and maybe some swelling.

Generally by the time an EV battery is down around 60% SOH it's becoming less useful for a car as the range will have dropped a lot, and manufacturer warranties sometimes allow for it to be replaced if it gets that bad too soon. When those batteries are replaced the old ones often turn up on the secondary market for non-EV use, like in this case. They can't handle EV currents anymore, but they still usually have a few years left in them if they're treated nicely and don't have to supply hundreds of amps anymore.

 

[time2roll]

Any heat will also cut the life significantly. 20C to 25C max cell temp. Yes slow charge/discharge is best.
I hope it is a low price. Would you have to pay to dispose of it?

And yes I had a new 2011 LEAF back in May 2011. I drove it 3.5 years. Terrible battery.

 

[neilnz]

The price is low by local standards, but not globally. Being in New Zealand has certain small-market downsides, like price gauging for LiFePO4 cells and it being somewhat uneconomic to ship moderate quantities of batteries from China. This has me looking at leaf batteries as they're probably the most mass-market way lithium cells get imported here ?

I would probably have to pay to dispose bad cells, so getting something completely unworkable is probably not worthwhile. A complete gen 2 leaf battery at 70% SOH can be had here for NZ$5000 (US$3000 at time of writing). I see all sorts advertised on here in other places for a whole lot less, which is sad.

Thanks for the tips though, I might need to look harder at some gen 2 packs, or something else.

 

[Vigo]

Is the SOH number including pack imbalance issues in its calculation? I did a training seminar led by a guy who had rehabbed an old Leaf who said that due to the way they do balancing you can drive the pack severely out of balance just by operating it a certain way, and that rebalancing the pack (by operating it in a different set of conditions that actually allow it to balance more) led to a huge proportional gain in range.

So that makes me think unless SOH just ignores imbalances, there's a good chance the pack is severely imbalanced and correcting that would add a lot of capacity back.

 

[yabert]

I've been offered a complete 24KWh gen 1 pack for a reasonable price, but it's at 36% SOH.

Umm! to me, this pack worth almost nothing. Gen 1 leaf cells are not great, there are old and the SOH is bad.
I'm a huge fan of reusing EV cells/module to build battery, but an old leaf battery is not a good deal, except if you pay very little for it.
An alternative could be to start to look at most popular EV on the road in New Zealand, look at the battery module and try to find battery at scrap yard.
Tips: Kia EV6/Ioniq 5 have really nice 6S battery module and with 77 kWh you will probably end to resell most of the battery to lower your upfront purchase cost... except if you look at a huge solar battery