I want to go from a 24 volt to a 36 volt trolling motor on my boat; however, I really don't have room for a 4th battery. I am thinking about a dual purpose battery cranking/deep cell for the motor and then including it in on the trolling set up to give me 36 volts.
Is this do-able???
Does anyone have theirs set up this way?
If you do are you having any problems doing it this way?
Am I going to have problems with my electonics hooked up with my trolling motor batteries?
Help.............

Do-Able,BUT not adviseable.Both Minn Kota and Motor Guide will VOID YOUR WARRANTY if you use the cranking battery as a trolling motor battery.

Foster's Trolln Motors/ ATV any ideas on fitting another battery in an already crowded compartment???

Jim Payne with Stayncharge.com can answer your questions about going to a 36 volt and also the room that you can save by using an All Charge charger. The units do not generate any heat and they weigh less than a pound. Worth checking into!

Is that something new? My 2001 36 volt trolling motor has a starting motor as the third battery setup in the manual.

The stayncharge system is not to be used in a three battery 36 volt system where the third battery is also the starter. I asked that question on BBC. I have not found a charge on the water system that allows charging with this setup.

David you are correct about the stayncharge it can not be used with charging a 36 with one battery used as the start battery.,You can use the system to charge all three if you are just using it from the tow vehicle while pulling the boat on the road but not off the outboard with that set up. Our customers have taken the heavier AC charger out of the boat and added another battery.

I have this setup and have been using it for a month with a few sun up to sun down days without any problems at all. I have a few buddies who have their boats rigged the same way.

I will say I did call MK before I did this and they say while it isn't advised it DID NOT void the warranty. I wouldn't have done it if it did void the warranty.

Allison1 Thanks for the info, I think I will give Minnkota a call early next week and see what they say. Thanks again..

I think the really big issue here is that if you do rig your boat in this manner and run your batteries down, you may not have enough juice to turn the motor over thus leaving you stuck on the lake.

fishing nut, I have a question. What size batteries do you have now and how much longer until you change them out?

The reason I ask is that if you can wait until you are getting new batteries you might think about getting a smaller battery. I have a very small pair of batteries that I use. They are troll fury (so small my stretched hand is longer than the battery). They are very small and were with my Allison when I bought it. They still work good (made in 99) and I have used them along with a larger absorbed glass mat(agm) battery in a 36 volt system. If you can redo the whole system you might look for some smaller batteries along with an on the water charging system like the stayncharge. Three group 24 batteries would be plenty large enough and maybe smaller would do.

As soon as the troll fury batteries I have go out I am going to start using three small (80 amp hour or so) batteries along with the stayncharge and I think it will be more than enough for my fishing. I have fished a tournament that I stayed on the windy side of coves most of the day with 30mph winds and the motor was still strong at the end of the day. I do have a light weight boat though.

Sorry for the long post.

If you do decide to run a three battery setup here is a thought. Run a dual purpose large starting battery. I ran a 29 walmart battery in my setup.
The two trolling motor batteries run deep cycle 24 group batteries.

By doing this you should always have more left in your starting battery. In theory, the amount of power that can be taken from any one battery in your 36 volt system is equal to what the weakest battery can supply. As the batteries drain, your starting battery should continue to have more potential than the other two. At what point the starting motor will not work I do not know but in my system I ran the trolling motor normally and never had a starting problem.

You could experiment and take a small starting backup battery along with you once you get your system builtup and then run the batteries down. It would tell you how far you can go. A DFI motor requires more starting power than a nonn DFI. I did have a DFI (optimax) 200 when I last used the three battery system. I always worried about it when I used the system hard but it never failed.