I am using two different 8s LFP batteries, each one equipped with a SmartShunt. The older battery has an Australian EV Power cell module BMS, which has an almost neglible self consumption and the SoC estimation of the SmartShunt works almost perfectly (off by a few % after 10 months of idle).
The newer battery is built with a JK BMS. When this battery is sitting in idle, the SoC drifts way off pretty fast. After just two months of not using the battery, the SmartShunt SoC now displays 65% (due to the Cerbo), while the cell voltage is at 3.0V at idle. So the real SoC is now close to 0..10%. I think I understand why this is happening: the BMS is directly connected to the negative battery terminal, as suggested by the manual. The SmartShunt is the next device in the ground wiring, but obviously, the SmartShunt cannot sense the consumption of the BMS now.
I therefore wonder how safe it is to put the SmartShunt between the BMS and the battery pole? What should I do with the "thin" ground wire from the cell voltage sense connector of the BMS? Is there any danger involved if the ground sense wire sees a more negative voltage than the current carrying ground wire of the BMS (due to the shunt's resistance)?
Has anybody tried this approach before?
