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Deep cycle marine batteries

I need some advice on charging a boat battery that I use to power an electric trolling motor. How often should it be charged when not being used, like over the winter?

I don’t recharge my deep cycle battery until I put it back into service. Deep cycle batteries are designed to be deeply discharged and recharged. Unlike with automotive starting batteries, if the charge isn’t maintained, the battery sulfates and turns into junk.


So I should let it sit over the winter and charge it in the spring. I use a trickle charger and let it charge all night. Does that sound about right?

Thanks for the reply.

They’re designed to survive a deeper discharge than a starting battery but they still are much better off if recharged immediately. If you let it sit discharged, it will sulfate the same as any other lead-acid battery. I trickle charge mine once a month, same as all my starting batteries.

Hi TwinTurbo,
Thanks for helping me out with this problem. My last deep cycle last about 6 years, but I didn’t charge it over the winter. I’ll start charging it monthly.


Harbor Freight has a float charger for only a few dollars.