Strange multimeter findings on JK active balancer solved

[JJJJ]

Before attaching my BMS I did a multimeter lead test and the voltage increased as expected across the leads from negative to my last lead.

I attached my BMS and turned it on. The voltages were as expected. Wire resistances were the same.

I checked the voltage from positive to negative on the battery, it read 26.36v dc.

I checked the voltage from negative on the battery to the positive lead outside the battery box it read 26.36v so the breaker and wiring on the positive seems to be operating OK.

I checked resistance from the positive terminal of the battery to the positive battery case output. It read 000.0

I checked the resistance on each side of the BMS, attaching my leads to each negative terminal on the battery and then on the power side at the exiting negative terminal. Everything read 000.0.

When I checked the voltage at the battery case terminals it jumped all over, never holding steady. It fluctuated from 0 to over 200V dc. This is a 24v battery.

I am confused. Since the BMS is reading steady, I wonder if one of the wires exiting the BMS has a poor connection? Again not sure why I didn't get any resistance at that end.

Looking for help. Thanks in advance

 

[DIYrich]

Was there load on the terminals? I see the bms is not letting power through (discharge off).

If there is no load on the terminals, it may be an artifact (voltage leakage of a nominal amount).

 

[JJJJ]

No load. No charger. No inverter. Stand alone battery

 

[sunshine_eggo]

If discharge is off, the battery terminals will not measure a valid voltage. Are you sure what you were seeing WASNT your meter in auto mode showing random mV values and not whole volt values?

 

[JJJJ]

I double checked. These were whole volt levels. This was reflected between the positive and negative battery terminals, the negative battery terminal and positive battery case terminal. This was also properly reported by the Bms software.

I suspect the problem is where the wire has a butt connection between the Bms and the battery case terminal. Because the values jump around I suspect a loose connection

 

[Quattrohead]

There is no way you were measuring 200 volts from a 24 volt battery, I think your multimeter was having a fit on you.

 

[JJJJ]

think your multimeter was having a fit on you.

I agree. I suspect a short in the line between the Bms and battery case terminal

 

[sunshine_eggo]

I double checked. These were whole volt levels. This was reflected between the positive and negative battery terminals, the negative battery terminal and positive battery case terminal. This was also properly reported by the Bms software.

The BMS software was reporting 200V?

 

[JJJJ]

Multimeter. I suspect it was confused. It was jumping around

 

[sunshine_eggo]

Multimeter. I suspect it was confused. It was jumping around

If it's auto ranging, that's normal when there is no voltage present.

 

[JJJJ]

OK. @sunshine_eggo tried to help me see this but I missed it. @upnorthandpersonal explained that all I needed to do was turn charge and discharge on on the BMS settings.

A rookie mistake. However I share this in case anyone else has the same issue so they can avoid the same frustrations I encountered.

 

[sunshine_eggo]

I think @DIYrich pegged it first!