I know there are quite a few posts on the forums about trolling motor batteries.  I know this because I have read quite a few.  My question is, is there a problem with using two different size batteries?  Right now my trolling motor is running off a size 29 and a size 27 (the previous owner had it set up this way and I haven't changed it yet).  I would love to run two 29 size batteries but there is not enough room for it.  Now it is time to replace my batteries, should I keep the same set up, or switch to two size 27 batteries?

 

As always,

Thanks in advanced.

It will work with two different size batteries but charging them could be an issue after every use and it will eventually cost you battery life and problems with charging/running. You're replacing them anyway so not getting two of the same would be stupid. Switch them both out to 2 of the same battery. The TM will only run as good as its weakest link. I.E if your 27 is "less battery" than your 29, it will still only run as good as the 27. 

That's pretty good advice.

Thanks for the advice, charging hasnt seemed to be an issue, but then again i havent been happy with the batteries in a while so that could have been caused by the charger... Once again thank you for the help

When you replace them replace them with the same batteries and consider selecting some AGM batteries. They allow you to use more of the charge and still get good results. Also if you can find room on your boat look at an onboard smart charger designed to charge agms. Select a 10/10 charger, one that supplies a total of 10 amps to each battery.  They will give much better service life doing it this way

I have a 27 and 29 in my Lowe because of space. At the end of 8 hours of fishing the 29 is down 15% and the 27 10%