Welcome! Need support, you got it. Or share you ideas and experiences.
I have an idea of how to recharge my trolling battery when it dies by my engine alternator. I have a seperate starting battery. What I wanted to do was have a switch that I could turn on to charge the battery when needed with engine running. I was wondering if anyone has done this.
Your idea is sound in principle but not wise in practice. As long as the engine is running and the wire gauge is capable of handling the alternator output, the juice will get to the battery. However -- if you stop the engine, and attempt to restart it with the trolling battery switched in, the wire gauge is not nearly big enough to handle the starting current draw and you will smoke the wires, (or worse, your boat). An isolator is a large diode that allows current to flow one way (toward the battery) but not backward for just this reason.
You need a battery Isolator. its like a 29 dollar thing around here
you can see one at the site below. I just did a search for it and took the first 1 I saw to give you something to look at.
You could also do it with a home made switch setup, But I think in this case, its worth the 30 bucks to just buy one.
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