Hello,
I'm debugging an application with 4 cells of LiFePO4, in which there is an irregularity on the recharging of the batteries.
It was reported that, once the batteries had been discharged, sometimes they wouldn't charge back again until a certain time had gone by. My setup test draws 0.25mA and takes about 10h to discharge.
At a closer glance, it showed an irregular behavior on the recharging flags during its discharge. After different tests, I came to realize that the ChgVolt and ChgCurr are (part of) the problem.
In other words, sometimes these registers which indicated the battery would accept charge were triggered after a few hours into the 10h discharge (as early as 3h) and, sometimes, would only trigger after the battery had been fully discharged, or even days after that.
Moreover, there is no relation to what Cell/Pack voltage triggers the desired changes; this can be seen on the table below.
Test ID | Discharge Time | CharVolt Triggered | Vcell1 | Vcell2 | Vcell3 | Vcell4 | Vpack |
1 | 9h57 | Not trig within 10h | |||||
2 | 9h51 | 11h15 | 2843 | 2854 | 3024 | 2875 | 11611 |
3 | 9h50 | 3h | 3273 | 3275 | 3281 | 3267 | 13100 |
4 | 8h14 | 7h43 | 3152 | 3157 | 3161 | 3148 | 12627 |
5 | 9h57 | 3h10 | 2699 | 2724 | 2925 | 2714 | 11106 |
6 | 9h56 | 82h38 | 2720 | 2746 | 2986 | 2781 | 11251 |
7 | 9h57 | 35h | 2803 | 2820 | 3014 | 2846 | 11480 |
I could say that this would be solved if I could directly input the Cell voltage at which the battery will trip the ChgVolt and ChgCurr; however, I could not find anything of the like on the technical documents.
Where can I input such value to directly set that, after dropping below certain voltage, ChgVolt should trigger?
Ideally, as little as 15 min discharging would have to trigger it, enabling recharging the battery if the outside source is back on.
I have tested with both unaltered Chemistry settings, and with adjusted Chemistry settings for the LiFePO4 cells. All cells are successfully balanced during the charging, and as far as I understand, did not overshoot.
I will gladly provide any additional information. I could not solve this matter even after extensive reading of the Technical Manual, Datasheet and other pertinent documentation.
Thanks in advance,
Daniel Gebbran
ChgVoltthat |