12v to 24v Trolling Motor Upgrade

Update: 

Got the boat out of the shed last weekend and started digging around the front of the boat to see what I all need to do to upgrade to 24v. Was expecting to have to pull and replace the wiring but after seeing "12-24V" on the quick disconnect plug, I was happy to find 6 gauge wire already in place. Sylvan wired it for either so that's gonna save me some time/money. The 60 amp marine circuit breaker arrived today and I will be ordering the motor and onboard charger this week. 

Thanks to you all for the advice/tips. Hoping to perform sea trials in the next couple of weeks to work out the kinks before the Opener! 

Bugle, in your case with such limited use on your existing single battery you could break the rules and use it for one of the pair to get 24 volts. A matching battery would be best. 

Related battery question:

I have read in multiple forums to get a matched set of deep cycle batteries for a 24 volt system. It's even mentioned below. If that's the best route to take, that's what I'll do. However, I replaced my group 27 deep cycle last spring with a Interstate. I hardly got to use my boat last season and never used the trolling motor. So the battery has never been drawn down or recharged. It's been kept on trickle charge most of the time. Should I still replace it when I pick up my second battery?

A 12V 50/55 lb Thrust trolling motor draws the same amps as a 24V 80 lb Thrust trolling motor and both require a 60A Breaker per Minn Kota's guidelines. Wire size is determined by amps not volts. There is an inverse relationship between volts and amps, longer runs require larger wire due to the voltage drop. If you are not moving the battery placement it should be a simple swap. Just remember to hook the batteries in series and not in parallel.

Super easy to do yourself.If the wire isn't 6 ga I would pull it and rewire it with 6ga and put it in a 50amp breaker at the same time. Then pretty much all you have left to do it is hook it to the trolling motor and batteries, though you'll need a jumper wire to go between the batteries for a 24v. Then hook up your charger to 2 new batteries and you should be good to go. As far as ​mounting a new trolling motor also very simple though having an extra set of hands is very helpful. 

Bugle Trout, 

This is an easy conversion,  Especially since you have room for two 12volt batteries.  You should be able to look at your current wires that go to the front.  Chances are you may need to upgrade although you could probably get away with 10 gauge, I would just pull it and replace with 6 gauge.  Use the same gauge wire to hook your new batteries that should be identical in make model and age in series.  Make sure you have a minimum of a 40amp fuse in line and you will be golden.   The other consideration is if you have an onboard charger you will need to run a 12 volt run to each individual battery to charge which is perfectly fine.

If you are adding a second battery to make 24 volts strongly consider getting two new matching batteries. If your existing battery has much more than 6 months of age it will or soon will be the weak link of the 24 volt system and not preform as you want. Don’t get caught in the cycle of replacing one then the other over and over.