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Multiplus II internal SoC jumps before absorption begins


Lately our Multiplus II (12/3000) frequently sets the SoC from like 40% to 80% for no obvious reason.

Batteries are 560 Ah of LiFePO4 cells with Daly SmartBMS (but Multiplus uses its internal battery monitor, no data connection to the BMS). The sudden jump to 80% is most probably from the "State of charge when bulk finished" setting - but the batteries were far away from bulk finished when the jump happened (actually the 30% were correct).

My guess is that the voltage raised over the absorption voltage of 13.80V for a very short period of time (not even visible in VRM portal - voltage was around 13.60-13.70 at the time the jump happened). Maybe it was also just a single false measurement causing the jump? The 80% are then held for a longer period until bulk actually finished, then the SoC is correct again. But if the charge was ended after the jump (e.g. due to cloudy weather), the SoC would remain terribly off...

Anyway - is there a possibility to make "State of charge when bulk finished" less sensitive, like it requires to be in absorption for 10 seconds at least or so? The batteries seem to be healthy, cables are rather oversized, I don't believe there is an electrical issue. The absorption voltage of 13.80V may be a little bit low, but is recommended for the CATL cells, with an absorption time of 2 hrs.

Thanks for any hints!

2 |3000

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