Jk inverter BMS - voltage loss?

[bluenomads]

New 200a JK inverter BMS. Connected in 16s all ok and showing up in their app fine.
But there's a 4v (not mV!) loss between the negative terminal going in to going out of the BMS. 52.72v from positive battery terminal to BMS in, and 48.18v from positive battery to BMS out. You can see where I'm measuring negative in the photos.
Any ideas?

 

[hogback]

Is the bms off or discharge disabled when you take the reading? If so, that could make sense.

 

[bluenomads]

Thanks for the reply. Voltage reading difference is with BMS on or off.
But, you are right about the Discharge: 4V out when disabled but "only" 300mV out when enabled or 0.6% loss in the BMS.
So I've got voltage thank you!

Any idea why the 300mV loss through the bms when it's on and discharge is on?

 

[hogback]

Maybe check the drop when there's a bit of current flowing?