hi,
i’m using Victron SmartShunt to monitor my solar batteries.
i’ve been monitoring the battery SOC from internal BMS software too and it seems the battery has it’s own drain even if not used (i assume this is to power the BMS?). it’s a cheap battery, so i don’t really mind the drain.
the problem is Victron SmartShunt didn’t/can’t register this drain since the current didn’t flow externally. the result is as expected, the SmartShunt always report higher SOC than the internal BMS.
how do i “tell” the SmartShunt to compensate this drain?
technical data as follows:
3x 48V 100 Ah LiFePO4 (15S battery, not 16S)
every battery, when cut off from the busbar drain around 0.33A (the SOC also reduced after a while, so it’s not some error in monitoring tool)
SmartShunt vs BMS SOC difference is in 10-20% range
i’m afraid if the SmartShunt still in 20% range, the battery will shut itself down (because SOC already 0% according to BMS)
*currently i’m using 20% as low SOC value, so SmartShunt will detect time remaining
The settings look OK. How often do your batteries get fully charged so both SOC values reset to 100%. If they spend a long period between full charges then any discrepancies will keep increasing. It is not just the BMS, also any self discharge along with any differences in accuracy between the devices. BMSs do not often include accurate shunt based measurement. To avoid the discrepancy growing make sure they get fully charged routinely.
There are reports of some cheaper BMSs of being inaccurate and some needing a settling in period.
usually they fully charged everyday
but if there’s less sunlight, they didn’t fully charge and the difference “grew”.
the SOC value between the SmartShunt and BMS began to differ without any pattern since they both seems evaluating different “loads” (that’s why I’m asking this now)
I understand if the BMS might be inaccurate, but isn’t the battery will shutdown if the BMS get very low SOC? since the BMS also control the battery?
currently I’m still monitoring both BMSes and SmartShunt but it would be nice to monitor only 1 source
