Multiplus 2 drains battery when DESS target soc = soc with 118 watt in idle discharge mode

[JeroenSt]

I think the jkbms is in error. While it says 2,4 amps of current, the battery voltage doesn’t drop.

[JeroenSt]

So I got a current clamp and the victron is drawing 0,3 amps, so the jkbms is completely wrong with measuring 1,8 amps.

I will send JK an email but I really doubt they are going to solve this.

I now use the measurement of the victron to calculate the soc which works fine.

[Sarowe1990]

A well-known and much discussed problem. Soc calculations about BMS are crap

[JeroenSt]

It isn’t even the calculation, the current measurement at low currents is completely wrong causing a soc drift.

A friend of my has the same jk bms and his bms doesn’t have this wrong current measurement.

Let’s see if JK will give support or an exchange on this faulty bms.

[Sarowe1990]

Your BMS is not broken. This is a general problem whether it is a JK or another manufacturer. But feel free to try it.

[JeroenSt]

I now discovered (again?) that in inverting mode the jk shows the correct current. Maybe a ripple of the victron when conneced to grid is causing the jkbms current error?

I will connect an oscilloscoop to the 48 volt bus later on to see if I can see any ripple or distortion.