View Full Version : Battery Question

11-06-2005, 08:38 AM
I bought my boat 3 years ago and have very low hours on the trolling motor batteries. lately I seem to get ony 4 hours on the river out of them. they are deep cycle and take a full charge. My neighbor suggested I dump the fluid and refill them with acid. Any help would be appreciated to get them to last longer if possible.



11-07-2005, 12:36 PM
You don't mention what size boat/trolling motor/batteries you are using and at what speed. If you previously were able to use for a much longer duration then perhaps it's time for new batteries. Batteries must be kept fully charged when not in use. Recharge immediately upon return from any fishing trip. Use a good multistage charger. If you have two batteries get a dual charger.
Buy a good battery charger, it will help your batteries last longer. Don't use the automotive type.
4 hours is a long time for a trolling motor running continuously at high speed.
I have two boats with electric trolling motors. On my 18ft pontoon boat I get 4 1/2 hrs at 2.0 MPH using a 74 lb thrust 24V Minnkota powerdrive (auto/co pilot) with two group 31 batteries. Lasts longer at slower speeds (like for Kokanee) . I get slightly better performance from my 16 ft alum with 55 AP Minnkota 12v with dual group 27 batteries.
For maximum performance I change out my batteries every three years.
Rick "Big Minnow"

11-07-2005, 01:39 PM
Big Minnow. Thanks for the help. It makes sense. I have an 18 ft lund that is alway loaded. we troll between 2-3 mph. It is a 55 lb thrust. Probably a little small for the size of boat.

11-07-2005, 07:50 PM
What kind of battery (specifically)

11-08-2005, 01:31 PM
Interstate megatron. Deep cycle RV/Marine.


11-10-2005, 04:12 AM
The best (and I have gone through many) deep cycle battery I have ever owned was made by Donnelly (of San Jose) for their self propelled wheelchairs. That battery out lasted and out performed any battery at any price that I have ever owned. I believe that the performance of a deep cycle battery has more to do with the number of plates than the size/weight. The plates were also set up higher off the bottom of the cells so more byproducts could build up before the cells short out (this is what usually kills a wet cell battery). Unfortunately Donnelly doesn't sell to the general public.

Changing out the electrolyte in a battery will extend the life only marginally and is very dangerous (acid burns and flamable gas). It's the degradation of the plates that cause a loss of performance. I wouldn't recommend going that route.

11-11-2005, 03:26 PM
Thanks for the information.


11-14-2005, 08:34 AM
Minn-Kota sells some stuff called Battery Equalizer which is touted as helping to prevent sulfation (a sulfate layer on the lead of a battery plate which eventually causes a battery not to fully charge). I personally have not used this product, but it might help with a new battery.