#### z1ppy

##### Well-known member

looking for some advise from the technical collective....

How can you test the drain on a battery or batteries (when connected together) on a boat?

We have 2 batteries on board with a 1 / 2 / both / off / isolation. I suspect there is a significant draw on the batteries either when isolated or when running...

I am not technically minded so need to try and understand how to measure the draw, i assume that if we start with everything off then switch things on we can find out where the draw comes from and thus what is flattening the batteries?

From there we can also establish what power is being returned to the battery via the alternator....

any help greatly appreciated as i am scratching my head here.. (please try and be as simple as possible as i am dumb!)