Boat Wiring

[Jmac77]

I recently bought a new fish finder for my boat.When I start the motor the fish finder shuts off.I am going to purchase a new battery and run the electronics separately from the starting motor.The motor keeps the battery charged so I am wondering how to wire the batteries together so both batteries are being charged without affecting the fish finder.

[captnn]

I ran my fish finder direct to the spare battery. When I wanted to charge the spare battery I used battery cables.

[Chrisb]

Fish finder shutting down on cranking is likely your battery being week or too small. The crank currrent is pulling the voltage down below the finder low minimum.

To run two batteries and have them charge when the motor is runing is best done with an A-B switch. You can run the motor off battery A or battery B or BOTH. You would set it to both when runing so both batteries charge.

I think there might also be a way to do it with diodes.The diodes would need be quite large to pass the cranking current.

[walleye5]

battery isolator, hooks up to both batteries and motor will charge the weakest one when running, or the battery switch as mentioned above, best to have a cranking/deep cycle battery you can get the dual purpose batteries. that's what I use on both my boats.

[Botchegalupe]

You need a dual battery switch, it's not a difficult job to complete. Here's a wiring diagram for the setup and make sure you should use 2/0 gage wiring. I installed one on my boat a few years ago, it shouldn't take more than 3 or 4 hours.