Battery switch, how do I use it?

[RupertW]

Hi Rupert,
Thank you very much for your advice, your solution provides an quick inspection every time I start the engine. Good idea.

I don't understand your description below:

" If it dropped low after putting it to BOTH then I'd put it to Batt 2 and allow that to rise to 12.7 before going back to BOTH."

When switching to BOTH, both batteries are charged (if needed), why do you switch to Batt 2 and wait for fully charged then
switch back to BOTH? Can't I just remain in BOTH?

My habit was probably over cautious but if Batt 2 (domestic) is discharged, say down to 12.3 volts, and Batt 1 is fully charged as normal at 12.7 or above, then switching to BOTH, especially with low engine revs as you unpark, will really be discharging Batt 1 into Batt 2 at a much bigger rate than the alternator is charging.

So by the (maybe over complicated and maybe unnecessary) habit of switching to Batt 2 you get Batt 2 up to Batt 1s charge level (ish) before going onto BOTH, so that Batt 1 never gets significantly discharged into Batt 2.

 

[peterjaw]

OK, I got your points. Thank you very much.