How much life is really left in these used cells??

crossy

Solar Enthusiast
Please note, we are located in sunny (actually rather wet at present) Thailand so any deals discussed probably won't apply, sorry.

I first mentioned these cells in the Internal Resistance thread https://diysolarforum.com/threads/cell-internal-resistance-what-does-it-mean.9274/post-300507 , but to avoid that going waaay off-topic I've started a new one here.

Anyway.

We have a local supplier with a "container load" of used CALB (allegedly, they are unmarked) golf-cart 200Ah LiFePO4 cells which he imported from China. He's selling them at about US$50 a pop and is using a LQ1060S ( https://www.aliexpress.com/i/4000083091762.html ) IR tester to show that they are good and weed out any non-performing ones.

I bought 17 (48V pack plus a spare) on-spec. to see what they're actually like.

Who knows if they really are CALB, Thailand is definitely the Land of Fakes (wanna buy a Rolex, really cheap?). They are certainly used but apart from a few pencil markings and numerical stickers which don't seem to mean much are totally unmarked, no dates, no QR, nothing.

They are supposed to be 200Ah but it seems CALB also do a 180Ah in the same form-factor, so who really knows.

Anyhow, whilst the 16 for the pack were top-balancing I put the 17th cell on a capacity test.

Charge at 6A to 3.65V. Have a pot of tea (I'm a Brit, we alway have tea on the go). Then constant-current discharge at 20A (the most my dummy load will do) down to 2.5V.

Result 168Ah.

So, if it's 200Ah cell that's 84% of original, if it was originally a 180Ah then it's at 93% of original.

Assuming the worst (84%) how much life is likely left in these cells? They will get treated pretty gently max. 30A charge/discharge, 70% DOD based on the measured capacity.

Thoughts welcomed, including "You are a complete idiot!".

EDIT I just found this thread https://diysolarforum.com/threads/aliexpress-beware-oye-store.23843/ and this one https://diysolarforum.com/threads/w...t-lifepo4-200ah-new-a-grade-calb-cells.24856/ and I suspect I have the same cells, at least mine were sold as used.
 
Last edited:

RVLiFe

Solar Enthusiast
1/4 the price and 80%+ capacity, so how exactly did you go wrong? You should get many years of service off of those. I’m sure there are a lot of people that would love to have a 48v system with over 9Kwh for around $900, including myself.
 

crossy

Solar Enthusiast
Yeah, I don't think I went wrong exactly, more looking for reassurance that a LiFePO4 at 80% of rated capacity isn't going to die in a few hundred cycles.

I know pretty well zero about battery life / performance, hence my asking here.

It does seem from other threads that some sellers with fewer scruples than mine are passing the same cells off as new, not good :(
 

Bud Martin

Photon Sorcerer
It is good deal, and you can follow up how well they work out years from now so we can have real world result on these used cells.
BTW, which part of Thailand are you at? There are some members here that live in Thailand also that you may want to get in touch with.

Sawat Dee krub.
 

crossy

Solar Enthusiast
We are in Sam Khok, just north of Bangkok, good to see other members here. Certainly worth contacting.
 

Watchout

Solar Enthusiast
Yes, you made good on that deal actually, and wasn't taken off guard that the cells would be new.

I have identified several sellers on all platforms promoting do called "NEW GRADE-A 200Ah CALB" LiFePo4 cells, using almost if not totally identical marketing material, same rhetorics, same denials and lies, and ALWAYS offering 0 compensation.

They also claim the QR-codes are unreadable, part of their generic script to evade claims of falsehood re-labelling.

But QR codes are indeed very easily readable, and should of course match the paper stickers they have glued on.

Typically their labels state 190827 as part of the model number and P921... as the production series, but I have seen and received cells going back as far as P641..., P715...

Now they even offer some from EU-stock !!!

Both OYE and PWOD store (the same people by the way) are part of this scheme, but several others have also jumped on the bandwagon for quick profits.

Ask to see pictures of the cells they offer you showing paperstickers and if possible QR-code, if they say they can't or won't or it isn't important, run away as fast as you can.

Watch Out.
 
Top