BX100 1-8S Lipo/Li-ion/LiFePO4 battery voltage tester alarm

Batteries and Chargers Chargers
1

Just bought this:

https://www.ebay.com/itm/BX100-1-8S-Lipo-Battery-Voltage-Tester-Voltage-Buzzer-Alarm-Remote-Control-Parts/142513518425

I guess this is a dressed up in rubber version of the 1-8S Lipo/Li-ion/LiFePO4 battery voltage tester alarm.

Any of you can say something worthwhile in this regard? Gonna use it to monitor a 4S LiFePO4 battery. I wonder where does the thing sucks the power from, it should do from between V− and V+ (topmost cell's anode), thus a switch placed in V− should power it off entirely. Anyone?

Hope it is accurate.

2

yeah i think a switch at GND is perfect to shut it off, but just to be sure, measure the current at the other pin.