Trolling Motor Batteries

[MackFisherman2]

I keep my trolling motor batteries (2) on a trickle charger when not in use yet can seem to only get 12-18 months life out of them. Never have a similar issue with my starter battery. Any idea why trolling motor batteries go bad so much quicker?

[coachlaw]

I'm not a real expert, just been working with batteries/solar for a while. I've got one deep cycle battery that is still giving me juice and it's from '07. I never let mine get below 40% because my inverters cut off power at 40%. The problem with trolling motor batts is that often they are run down to zero before charging. Depending on the model of your trickle charger, you may be over-charging if they stay plugged in for weeks on end. I know they're supposed to go into maintenance mode, but some cheaper models don't really do what they say. I have no experience other than what I've heard. I recommend wet cell Wal-Mart batteries. Keep 'em wet and don't let them go below 30% or so. They should last you longer. You might also try another charger and see if it works better. That's my advice. Your mileage may vary.

[Ibtsoom]

AGM batteries on my trolling motor - they sit on an onboard charger (minn-kota) when not in use. Haven't had any trouble and the improvement over standard deep cycle wet batteries for me was a 4 fold increase in running time before I need to recharge.

All that being said - I do tend to go through the trolling motor batteries a bit quicker than the main motor battery. When I had wet cells they also lasted 12 or 18 months on the trolling motor as compared to almost 5 years on the wet cell main motor battery. Just like Sandy said, I think it has to do with the run to zero / recharge swings. Got probably 30 months on this set of AGM's and they still seem to be doing good so fingers crossed.

Sandy is right on the charger quality as well - some of those little float chargers don't do what they say and overcharge. The higher end models work much better at maintaining without negatively impacting battery life.