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Battery Shutoff Question

S * K

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I took the batteries out of my boat last year and didn't do the best job marking the wires. I have battery shutoff switch and after reattaching and starting up the engine I got a spark and the positive side of the battery heating up on me on the #1 battery. I only ran my motor for about 10 seconds. I pulled some diagrams off the web and I have one hot wire coming into the shutoff and 2 coming out. One is going to one battery positive and the other to the 2nd battery positive side. I than have a jumper cable connecting the 2 negative sides. I thought this was right but I guess not. Any help or suggestions are welcome. I am thinking that its running 24 volts instead of 12. I have the selector switch on #1 battery and tried selecting to both and got a spark when i flicked it over :(

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If I'm not mistaken, the only way you can create 24 volts with two batteries is when you connect the positive terminal on one battery to the negative terminal on the other and then run the batteries in series. You will then be left with a negative terminal on one battery and a positive on the second battery creating 24 volts. Based on your description, you have not created 24 volts in series.

Usually the dual battery switch is hooked up:

Jumper the two negatives of each battery together, then you connect battery #1 positive to the switch #1, and battery #2 positive to switch #2 on the dual switch, Then the common wire on the switch goes to the starter on your motor. Make sure your second battery positive isn't connected to the common terminal on the dual switch.

- Chris

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Positive cable from first battery goes to post #1 on the switch

Positive cable from second battery goes to post #2 on the switch

Starter cable from engine goes to COM (common) post on battery switch

NO negative cables connect to the switch, they are bolted to the engine.

Both batteries negatives are tied together with heavy jumper.

[ Post made via Mobile Device ] mobile.png

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  • 4 weeks later...

There are two types of battery switches. One simple one is a direct battery disconnect switch, the other has protective switches to save your alternator diodes in case someone switches the battery while the engine is running. The better one has connections for the alternator charging circuit which disconnects before the battery is disconnected.

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