12 & 24 Volt Trolling Motors on Same Boat

[ZebraMussel33]

I recently bought a boat that came with a 12 volt transom mount trolling motor. Just the other day I purchased a 24 volt bow mount trolling motor that I will be adding to the boat.

The 24 volt motor needs to be connected to two 12 volt batteries wired in series... Is there any reason I can't just simply connect the 12 volt trolling motor to ONE of those batteries that are in series? So in other words the transom mount motor will be using one of the 2 batteries that the bow mount motor is using.

Based off of a 'circuits' class I took this seems like it should work out fine and both motors will be getting the correct amount of voltage. I just want to know if anyone else has done this or if for some reason this would be a bad idea.

Also, I will never be using these two trolling motors at the same time.

Zebra

[BobT]

Yes it would work but bear in mind that while using the 12v motor you will be draining charge from that one battery. As that battery gets lower on charge, its output voltage may begin to drop under load resulting in a less than 24v supply to the bow motor. Probably not the best thing to do for the sake of the 24v motor.

[fishwater]

or if for some reason this would be a bad idea.

I wouldn't try it. With a couple of throw switches you could change the 2 batteries from series to parallel - run the 24v bow-mount in series and the 12volt as a parallel setup. That way you wouldn't have to worry about creating loading issues between the batteries when they get out of whack in regards to their individual potentials.

[ZebraMussel33]

Thanks for the feedback guys I appreciate it.I didn't even think about using throw switches that is a good idea.

Thanks again.

[bobbymalone]

why do you need dual trolling motors? just wondering.

[BobT]

Be careful with the throw switch idea. Forget to switch it once and apply 24v to the 12v motor and you could be buying a new motor.

[fishwater]

Yeah, forgetting could be costly. A double throw transfer switch would be the way to go, essentially guarantee isolation of the two circuits. Finding something marine applicable might be problematic. Generator isolation switches would probably work OK.

[ZebraMussel33]

I only need the bow mount because I mostly cast for muskie however from time to time I will stop and fish for walleye. When I do that the transom mount motor would come in handy. When dragging lindy rigs or jigging I prefer controlling the boat from the back.

I wouldn't have bought a transom mount trolling motor but seeing how it came with the boat I'm just exploring the idea of having both...

I also did some more research on the switches and finding one that is marine friendly seems difficult as stated above. Perhaps it would just be easier to buy another seperate battery for the 12 volt. I'll let you guys know if I come up with something and how it works.

Thanks again for all the help.

[flyfisher03]

You could install a voltage reducer. Connect it to the 24v system and then hook up the trolling motor to the reducer. When I worked at a NAPA store a few years ago I know we sold a few of these to the construction companies that ran strobe lights, CB's, and other 12 volt accessories off their 24 volt systems in their heavy equipment.

[BobT]

How often would you use the rear motor and for how long?

What size is that rear motor?

I had a Lund Rebel 16 tiller for nearly 12 years driven with a 40hp Evinrude with electric start. I had a transom mounted 36# electric on the back. I used one dual-purpose battery for starting the outboard and running that electric. I could probably count on one hand the number of times I ran the battery down too far to start that outboard but it was so easy to hand pull it was no concern. If you don't use the transom mounted motor too much, maybe replacing your starting battery with a dual-purpose battery is an option to consider.

OR, you could just get another battery to power the rear electric by itself.

[Smallie Hunter]

I did this on my last boat. I had a 24v up front and 12v on rear. I usually fished for bass with the front and ocasionally use the rear. I never had an issue.