aurijinboat
New Member
- Joined
- Oct 31, 2022
- Messages
- 2
Hello,
I’m new to DIY LiFePo4 but I’ve been lurking for a few months and received 8 EVE LF280K from Docan following your advices. I also ordered a JK-B2A8S20P with Docan (see picture of the label on it) that I‘m having issues with.
The config now is 1P8S to precharge the cells for the first time before top balance, see attached picture. They are then to be used as 2P4S. I follow this guide.
I have access to a multimeter which is said to be 0,09% accurate for DC tensions, ie +/- 0,003V at 3,5V (keysight U1241B), however I don’t have a calibration report on it.
Under no load nor charger, the multimeter reads for all cells 3,326V +/- 0,001V vs 3,348V +/- 0,001V on the BMS. Seems OK.
To precharge the cells, I use a dual power supply, both outputs in parallel, at 28,8V 4 amps each.
Under a 8 amps DC charge at 28,8 V target voltage, the BMS reads cell voltage difference of around 0,09V and starts to active balance at 2 amps, while the multimeter reads 3,335V +/- 0,001V on all the cells. Same voltage difference on the BMS only with top balance off on BMS settings (see attached picture).
I sanded a little bit the contacts and cleaned with acetone with the same results.
Do you have any idea of what could induce the BMS to read unbalanced cells while they are if I trust the multimeter? Is the BMS faulty?
Thanks for your help
I’m new to DIY LiFePo4 but I’ve been lurking for a few months and received 8 EVE LF280K from Docan following your advices. I also ordered a JK-B2A8S20P with Docan (see picture of the label on it) that I‘m having issues with.
The config now is 1P8S to precharge the cells for the first time before top balance, see attached picture. They are then to be used as 2P4S. I follow this guide.
I have access to a multimeter which is said to be 0,09% accurate for DC tensions, ie +/- 0,003V at 3,5V (keysight U1241B), however I don’t have a calibration report on it.
Under no load nor charger, the multimeter reads for all cells 3,326V +/- 0,001V vs 3,348V +/- 0,001V on the BMS. Seems OK.
To precharge the cells, I use a dual power supply, both outputs in parallel, at 28,8V 4 amps each.
Under a 8 amps DC charge at 28,8 V target voltage, the BMS reads cell voltage difference of around 0,09V and starts to active balance at 2 amps, while the multimeter reads 3,335V +/- 0,001V on all the cells. Same voltage difference on the BMS only with top balance off on BMS settings (see attached picture).
I sanded a little bit the contacts and cleaned with acetone with the same results.
Do you have any idea of what could induce the BMS to read unbalanced cells while they are if I trust the multimeter? Is the BMS faulty?
Thanks for your help