Name:   sagetek1 - Subject:   Dual battery use question Date:   2/21/2020 12:24:16 AM

This seems to be a question for the ages, but recently installed identical regular marine batteries (not deep cycle) in my pontoon boat. Marina did this an put a simple 1-2 both switch on this. No special battery sensing switches or relay, etc. Question is , wha it the best way to operate these? Did this so that when pulling up to a sandy area on lake, can run radio, etc. without as has happened, run the single battery I had then low and had to get a jump to restart.

Anyway, what I am doing now, is when starting the engine for the first trip of the day (just a 70 HP) I run on both batteries. If we stop as indicated, based on the odd or even day of the month, put the switch on 1 or 2 battery. When leaving, I keep the current battery setting and assuming the engine starts (it really should), I run the rest of the day on this selected battery.

Putting the boat up, I turn off the switch. Next trip, start the process over. Theory is that the battery not selected after pulling up on sandy area, remains fully charged and should be fresh, and the battery used last coming back to marina should be fully charged.

Anyone have any other ideas on this, or is this the best you can do without sophisticated battery management systems.

Again, batteries are identical, both installed at same time, and check volt meter routinely to see if all looks correct/same on charging voltage coming and going for the day. So far, it has. Never had one die yet. Problem single battery was old, so put in this system a year ago. Plus I carry a jump box also. learned my lesson.

Thanks!