crossy
Solar Addict
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.
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.
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