Bongo Fury

I was considering wiring in a dual meter similar to this https://www.amazon.co.uk/Alamor-Digita ... B078GL4GQG.

I’d like it to be switchable (on / off). If I add a switch to the common negative(s) would that prevent unwanted battery drain from it running 24/7? As I understand the wiring, there are three terminals on the rear, two positives (one from each battery) and a common negative.

What do the electrical wizards think?

It may work, the only concern would be that there maybe inadequate isolation between the two +ve connections when the -ve common terminal is not connected, it may work for a while and fail at a later stage when there has been any spike on the either battery. This could be a quite serious fault as it could common the the two batteries together.

It may be better to fit a two pole switch to isolate both battery connections at the same time.

Thanks. I’m now thinking two pole momentary switch to avoid the possibility of the switch being left on. That way both batteries would be isolated and the voltmeter only work whist pressing switch.

https://sinolec.co.uk/en/double-pole-r ... FcEALw_wcB