24Volt Trolling Motor and two 12 Volt Batteries

[David Wolfe]

I purchased the boat with a 24 volt trolling motor, 1 working 12 volt battery and 1 dead 12 volt battery. The previous owner had removed the battery switch (claimed it drained both batteries) not really sure how he had the batteries connected.

I recently purchased a new 12 volt battery and switch and installed them in parallel. This will not provide 24 volts for the trolling motor, but does provide a backup battery for the outboard motor. What is the best way to connect 2 12 volt batteries in this situation? and what or the pros and cons?

 

[fishrdan]

Re: 24Volt Trolling Motor and two 12 Volt Batteries

The 2- 12V batteries need to be wired in series to get 24V for your trolling motor.

- from 1st battery wired to the + of the 2nd battery
+ from 1st battery and - from the 2nd battery go to the trolling motor

The engine would connect to one of these batteries for 12V.

With only 2 batteries, a 24V trolling motor and a battery switch,,, I don't see how it could be all connected and running properly since you would need at least 3 batteries in this scenario. IE: 2 batteries connected to the battery switch and then the 3rd battery connected (as stated above) to provide 24V for the trolling motor. (the 3rd does not connect to the battery switch)

Hope this helped and didn't create more confusion

 

[David Wolfe]

Re: 24Volt Trolling Motor and two 12 Volt Batteries

You are correct, the trolling motor is not connected at this time. Is your suggestion three batteries, one for the outboard and two for the trolling?

 

[Silvertip]

Re: 24Volt Trolling Motor and two 12 Volt Batteries

That's the only practical application. You have a 24V trolling motor. It takes two batteries in series to accomplish that. You only need one battery for the engine. If you need a jump start, carry a set of jumper cables or a jump start box and forget about trying to add a battery switch. A simple on/off battery switch could be installed to provide a momentary connection between the first battery in the 24V configuration and the start battery. The negative terminal on that battery would need to be connected to the negative terminal on the starting battery and no switch would be needed. I don't currently have a schematic of that configuration but if I get some time I will put one together.

 

[David Wolfe]

Re: 24Volt Trolling Motor and two 12 Volt Batteries

When get some time, that would be much appreciated. Does that provide protection from starting your engine with 24volts.

 

[Silvertip]

Re: 24Volt Trolling Motor and two 12 Volt Batteries

The switch merely connects a second battery in parallel with the start battery. It will not interfer with the trolling motor and there is no danger of getting 24 volts on the engine battery (provided you connect the switch to the correct battery). The switch in the OFF position merely disconnects the parallel connection to the start battery. I'll post this in a few minutes.

 

[Silvertip]

Re: 24Volt Trolling Motor and two 12 Volt Batteries

Here ya go. WARNING: When you wire up the switch make darned sure you connect to the first battery in the 24 volt string. Battery 2 will connect in parallel to the start battery when you turn the battery disconnect switch ON. Start the engine and then turn it off. You can run with the switch ON if you like as this would charge BAT 2. BAT 3 will not charge however but whatever charge you add to BAT 2 would be partially sucked up by BAT 3 until the two batteries are equal. And that means your start battery would be impacted as well if you leave the switch on. So while this accomplishes what you want to do, my suggestion is to use the switch only as an emergency start device. The switch does not impact 24 volt operation in any way. These switches are available at farm stores, auto stores, and right here on iBoats.