Battery / Perko question
 

Hey guys;
I just purchased 2 new interstate batteries. One starting, and one deep cycle. My Perko switch is marked: Bat 1, Bat 2, Both, and off. My question is this: When starting the boat, does it hurt anything if I select Both on the switch, and then just leave it there to charge both batteries? or should I use only the starting battery, and then move the switch to Both? This may be a dumb question, but I just don't know.
Thanks!!

I leave mine on both so my alternator keeps everything topped off. As soon as I anchor out for an extended period of time, I switch to my house battery bank. If it's depleted very bad, I'll switch to my cranking battery and rely on shore charging instead of trying to work my alternators ass off. If your not draining your batterys down for hours at a time anchored out, I'd leave it on both so you continually have topped off batteries.

So starting the boat on Both doesn't affect anything? Is the starter getting 24 volts instead of 12?

Nope the starter will always only see 12. On either or both.

Thanks Guys !!
Always a great help.

i always use 1 or the other never both that way i always have a back up then whenever im home they both get topped off with the trickle charger

Or you can spend ~$100 for the Blue Sea Add-A-Battery kit which gives you a new switch and Automatic Charging Relay and never need to deal with switching batteries again.

Since you have 2 different types of batteries and must have the stereo stuff all wired directly to the house/stereo bank I would start on battery 1 unless you know that both batteries are fully charged. with the switch in the both question it is like wiring them in parallel or having one large battery. When you stop and listen to music turn the switch to battery 1. This isolates the 2 batteries, lets you drain down the stereo bank without draining the starting bank as well as keeps your starting system hooked up to the starting battery so you don't have to screw with anything to start the boat. Honestly, if you have it wired the way I think you do you should very rarely ever put the switch in the battery 2 position. The only time you would need to is if you knew your starting battery was dead and need to start the boat off the stereo bank. That or you want to only charge that one battery instead of charging both.