I have a truck equipped with some emergency equipment that I'd like to be able to use without running the engine the entire time, and without draining the main starting batteries.
There is a 1/2/both/off switch in the cab, and it has two 12V batteries wired in parallel connected to post #1 in the switch. I'm thinking of getting a pair of marine/deep cycle batteries and hooking them up to the #2 post, so I can switch to that when parked.
I've been doing some reading and generally know what I'd need to do, but haven't been able to find a good answer to two things:
- Is it safe to use the engine to charge the marine batteries? For example, I use #1 to start, then switch to "Both" when it's running. Would that be OK, should I switch to #2 so it only charges the marine, or should I just use a battery charger when I get home?
- Assuming I use fully sealed batteries and put them in a plywood box, is that safe to mount under the seat in the cab? If so, would I need to add heat/vent holes?
Note: Question 1 assumes that the switch doesn't cut power when switching between batteries