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NH20 · 09-25-2016, 07:26 AM

A fully charged battery won't freeze until something like -75f, a fully discharged battery will freeze at about the same temp as water. Really, a lead-acid battery should never be left discharged, regardless of the air temp.

I pull my batteries and keep them inside on a tender (varies the charge voltage according to charge level, as opposed to a trickle charger) and swap in an older battery I keep around so the shop can run it to winterize it, and then leave that one in all winter. A bit of a pain, but only a small part of the winter layup.

I think if you can keep them full or near-full charge they should be OK over the winter in the boat.

09-25-2016, 07:26 AM	#6
NH20 Junior Member Join Date: Aug 2015 Posts: 1 Thanks: 0 Thanked 0 Times in 0 Posts	Keep them charged A fully charged battery won't freeze until something like -75f, a fully discharged battery will freeze at about the same temp as water. Really, a lead-acid battery should never be left discharged, regardless of the air temp. I pull my batteries and keep them inside on a tender (varies the charge voltage according to charge level, as opposed to a trickle charger) and swap in an older battery I keep around so the shop can run it to winterize it, and then leave that one in all winter. A bit of a pain, but only a small part of the winter layup. I think if you can keep them full or near-full charge they should be OK over the winter in the boat.