Guest Dual Battery Switch ??

[Salmonseeker]

First let me say I have read every post regarding dual batteries/dual battery switch. I realize that three individual swicthes is the best way to go. For now I want to hook up the switch and dual batteries. I have one outboard two batteries and one Guest switch. The switch has 3 posts, feed, battery 1 and battery two. My question is which post would be the best to attach the accessories main power feed to (This is a single 10 gauge wire w/40 amp breaker that feeds the switch panel at the helm)? The manual (that came w/ the boat) states that it should be attached to the feed post? It was attached to the battery 2 post, when I unwired it? Which is correct and why? Thanks so much.

[HOTSPOT]

Salmonseeker,

I have the same setup as you. I use automotive style cables, 4 gauge to make all of the connections. I used an anti-corrosion paint on all of the of connections.

I took the negative from my motor and hooked it to the negative on battery #1. I also hooked my accessory ground to the negative on battery #1. I then ran a 4 gauge "jumper" from battery #1 negative to battery #2 negative.

I took the positive from the engine and hooked it up to the "common" lug on the switch. I also hooked my accessory positive to the "common" lug on the switch. I then ran a 4 gauge "jumper" from battery #1 positive to the #1 lug on the switch. I ran another 4 gauge "jumper" from battery #2 positive to lug #2 on the switch.

The way I use this is simple. Each time I go out I alternate my battery selection. I very seldom run it in the "both" setting. I have always heard that this works best for the batteries and the engine's charging system.





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[Birdman]

SalmonSeeker,
You should connect the "accessories main power" (which feeds your helm..) to the "Feed Post" as the boat manual states. The "feed post" refers to terminal "C" in the diagram above. The resaon for this is it allows you to switch which battery (or batteries) you run your accessories from with the switch. If you wire it directly to a battery (as it was), you can ONLY run accessories from that battery. What if that battery fails while offshore? Then say goodbye to VHF, GPS, fishfiner, lights... Another reason is, it will allow you to turn off power to the accessores, by simply turning your bat switch to the off position.

If you have it connected to the feed post, and a battery fails, just switch the battery switch to the other battery, and your back in bidness.

Just make sure you leave the 40 amp(or another appropriate size) breaker in line, as close to the connection to the feed post as possible. This will protect your accessores wiring from fire in case of a short/failure, and protect your accessores as well.

Good luck.

Birdman, Capt of

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[Salmonseeker]

Thanks guys for the diagram and awesome explanation, makes sense.