JBD BMS 200a - Voltage in app and with meter don't match

[coltfred]

Hey all,

I just installed my JBD BMS and I'm seeing a mismatch between the apps reported voltage and what my voltage meter tells me. I'm hoping someone can give me a hint as to why it is. The setup is a 4S 12v system.

The app is reporting 13.58v, but if I test from the main positive to the C- on the BMS I only get 7.8v. I tested the connectivity of each of the cells in the wiring harness and saw that they were all around 3.3v. The app also reports them as being ~3.3v.

I haven't hooked up any load to the system but I did hook up a charger to see if that would behave as expected and it seems to. The cell voltages are going up slowly. My volt meter is new and seems to report correctly when testing cells directly as well as testing the battery pack as a whole (main pos to main neg).

Any ideas?

 

[Lt.Dan]

The BMS might have the Charging mosfets turned on, but the discharge mosfets off. In this case, it will accept a charge, but will show low or no voltage when tested with a DMM.

Does your App show the status of the Mosfets?

 

[Bob B]

We are probably going to need to see some screen shots from your App.