# Wiring 12V/24V trolling motor



## BigTerp (Apr 14, 2015)

I have an older Motorguide Pro Series trolling motor that is 12/24V. Has a selector switch on the foot pedal to go between 12v and 24v. It's currently hooked up as 12V only, but the lack of power is really getting on my nerves. I'm pretty sure I understand how to wire it up as 24V, but had a few other questions. First off I used 10AWG wire, a 50amp 12/24V manual breaker, and male/female 3 prong plug to hook it up. Will all of this suffice when jumping to 24V? Or am I going to need bigger wires or a larger breaker? Also, I currently have 2 group 27 batteries on my boat. 1 for the trolling motor which also has a 12V accessory plug and my second (emergency) 1100gph bilge pump wired to it. My second battery is my starting battery and also has all my 12V accessories wired to it which include LED nav and anchor lights, interior lights, HID driving lights, stereo, sonar and bilge pump. All are wired to my starting battery through a switch panel except for my sonar and HID lights. Will connecting these two batteries to make a 24V circuit for my trolling motor screw up any of my 12V accessories? What about my 2-bank on board charger? Just trying to make sure I don't fry any of my 12V accessories or my on board charger in the process.


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## Skiffing (Apr 14, 2015)

You're fine.

Double the voltage reduces the amperage [and voltage loss per wire size] in half.


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## BigTerp (Apr 15, 2015)

Thanks. So my wire and breaker size are good to go.

So no concern with frying my 12V accessories that are currently wired to my batteries? And my 2 bank charger can stay hooked up with one bank to each battery like it is now with no issues? I'm assuming once I wire up my trolling motor it will be the only thing wired properly to 24V, so it will be the only thing pulling 24V. Correct? Can I still leave my 12V accessories hooked up as is to each of my batteries? 

I'm still trying to figure out how to wire it up. My buddy wired it up for me when I was out of town. But I'm pretty certain he just wired up the 12 volt portion and left the 3rd wire (24v) unhooked. I need to take a look at my trolling motor receptacle to figure out what he did and where to go from there. If it is wired like I think all I need to do is take the 24V wire from my trolling motor plug to the positive of my starting battery then a wire from the negative of my starting battery to the positive of my trolling motor battery to complete the 24V system for my trolling motor. Does that sound right? What if I want to wire my trolling motor to straight 24V?


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## Skiffing (Apr 15, 2015)

BT - 

If you have two 12v batteries wired in series for 24v you won't be able to pull 12v from them without something like an ACR. In addition, the loads between the batteries will not be equal.

Post up a sketch.


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## bAcKpAiN (Apr 15, 2015)

You will be fine with your 12V stuff as long as you have them hooked up the the + and - of the SAME battery. I have a 36V system and have the motor starter attached to one of those batteries drawing just its 12v. I have my pumps and lights on a second battery drawing 12v and the fish finder is attached to the third. All three are hooked together to give my trolling motor 36V when it is attached to the + of the first battery and the - of the third. The charger is fine as well as long as the banks are setup on the individual batteries correctly.


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## JoshKeller (Apr 15, 2015)

remove the - trolling motor wire from the one battery and put it on the second. then take a jumper wire and attach it to the remaining unused terminals on the two batteries. Your 12v accessories will be fine and the charger will be fine.


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## matzilla (Apr 15, 2015)

use a marinco plug, then you don't have to jump the batteries or change your 12v accessories...the 24v is jumped at the plug


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## BigTerp (Apr 16, 2015)

Thanks!!

Been doing a lot of reading on this and the 2 drawbacks that I see are #1. The batteries in the 24V system will be unbalanced due to my starting battery having most of my everyday use 12V accessories hooked to it and the fact that my starting battery will also be charging each time I start my motor. Apparently unbalanced batteries can significantly shorten their life. Is that correct? #2. It seems that with 2 batteries in a 12V system one battery will only ever be 12V when a 12V accessory is hooked up to the + and - of that battery only. But the second battery will deliver 24V to my 12V accessories if that accessory is somehow accidentally grounded. Don't really understand that part, but I'm not interested in frying any of my 12V accessories or my motor electronics. Anyone heard of that?

What is the marinco plug your talking about matzilla? Sounds like that would solve my concerns of frying my 12V accessories since the 24V would be jumped at the plug.


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## fender66 (Apr 16, 2015)

You could also get (and probably will) get a lot of "noise" in your graphs hooked up this way. I'd be very surprised if you didn't.


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## JoshKeller (Apr 16, 2015)

i have all of my accessories hooked up to one of my 24v trolling motor batteries, simply because im lazy and havent ran wires back to the starting battery yet. no sonar interference, no issues of any kind. Im probably the hardest person on my trolling motor on this board (99% of the time its on full blast, i slam into rocks, etc). I fished 12 hours yesterday in 3.8 mph current, and my batteries were still going when I put the boat on the trailer at dark. plugged in the charger as soon as i got home, and this morning they were charged and ready to go again. 

I am currently toying around with the idea of getting a 24v lithium battery for my trolling motor to lighten my boat and make it even more shallow drafting. 

if you run your 12v stuff off of just one battery, theres no way it can get 24v. another option would be to get a size 24 starting battery and keep everything not 24v on it.

If you decide to go 24v, i wouldnt even bother running a third wire, just run it straight 24v to the trolling motor. you'll never use the 12v settings again. I know the areas you fish lol.


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