bigjoncoop
New Member
- Joined
- Dec 27, 2019
- Messages
- 9
I've got some 60ah & 100ah Lifepo4 prismatic cells (GBS-LFP 60ah/100ah) I purchased from batteryhookup recently. They are in good condition and have no signs of swelling etc...
This is the 2nd set of cells I tried to capacity test and the results seem like something if not rite... They have a rated discharge of 0.5c
The other day I fully charged 2 of the 100ah cells upto 3.55v per the datasheet using my tried and true ISDT RC/Balance Chargers. I then put them in parallel and hooked up my 150w capacity tester. I set the cutoff voltage to 2.5v per the datasheet. I then applied a 5a load and INSTANTLY the voltage dropped below 3v and at the end of the test it show a capacity of 40ah!!! No where near the 200ah rated capacity of the cells... I didn't expect to get 200ah since the cells are not new but also not 20ah per cell either...
Just like most LifePo4 prismatic cells these are rated at 3000 cycles to 80% capacity. So if they only tested at 20ah that would mean they have lost 80% of there capacity!.!.! That doesn't / can't be possible....
So just now I decided to capacity test some of the 60ah cells and after fully charging 2 of them and putting them in parallel and started testing them at only 3.5a they too instantly dropped below 3v to about 2.8v..... The test is still running but not looking good.
******
Does anybody have any ideas of why this might be happening besides the cells being completely garbage? I'm using 8 gauge wire and all the connections are nice and tight. And when I charged them up to 3.55v I definitely got charged all the way up considering how much time it took for the charger to finally STOP. Many many many hours with the charger set to 10a
It doesn't seem possible that both the 100ah and 60ah cells can only have 20% of their rated capacity left. I believe batteryhookup mentioned that these cells came from hospital computer carts, which would mean they had a pretty easy life and probably for a fairly short period of time....
Let me know what you guys think.
Thanks
***Update***
So the 60ah cells I've been discharging at 3.5a now for almost an hour and the voltage is still at 3.0v They seem to be doing better then the 1st test with the 100ah cells. But I thought the bulk of LifePo4 cells capacity was around 3.2v so I wouldn't have expected them to instantly drop to 3v when applying a small load but maybe im wrong...
This is the 2nd set of cells I tried to capacity test and the results seem like something if not rite... They have a rated discharge of 0.5c
The other day I fully charged 2 of the 100ah cells upto 3.55v per the datasheet using my tried and true ISDT RC/Balance Chargers. I then put them in parallel and hooked up my 150w capacity tester. I set the cutoff voltage to 2.5v per the datasheet. I then applied a 5a load and INSTANTLY the voltage dropped below 3v and at the end of the test it show a capacity of 40ah!!! No where near the 200ah rated capacity of the cells... I didn't expect to get 200ah since the cells are not new but also not 20ah per cell either...
Just like most LifePo4 prismatic cells these are rated at 3000 cycles to 80% capacity. So if they only tested at 20ah that would mean they have lost 80% of there capacity!.!.! That doesn't / can't be possible....
So just now I decided to capacity test some of the 60ah cells and after fully charging 2 of them and putting them in parallel and started testing them at only 3.5a they too instantly dropped below 3v to about 2.8v..... The test is still running but not looking good.
******
Does anybody have any ideas of why this might be happening besides the cells being completely garbage? I'm using 8 gauge wire and all the connections are nice and tight. And when I charged them up to 3.55v I definitely got charged all the way up considering how much time it took for the charger to finally STOP. Many many many hours with the charger set to 10a
It doesn't seem possible that both the 100ah and 60ah cells can only have 20% of their rated capacity left. I believe batteryhookup mentioned that these cells came from hospital computer carts, which would mean they had a pretty easy life and probably for a fairly short period of time....
Let me know what you guys think.
Thanks
***Update***
So the 60ah cells I've been discharging at 3.5a now for almost an hour and the voltage is still at 3.0v They seem to be doing better then the 1st test with the 100ah cells. But I thought the bulk of LifePo4 cells capacity was around 3.2v so I wouldn't have expected them to instantly drop to 3v when applying a small load but maybe im wrong...
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