winterizing batteries notes

A readers reply to Mark's Winter Battery Storage & Maintenance article

Hi Mark
Just wanted to add to your winterizing batteries notes:

It is my experience, 10+ years, of storing batteries in our frigid northern winters in Canada, where we get temperatures as low as -40 C (-40F) and sustained temps in the -20C to -30C for weeks on end, that if the batteries are topped up (fluids) and fully charged and the ground cable disconnected, the batteries will not freeze. It is actually better for them than removing them, banging them around, storing them in above freezing temperatures and as quite often happens, becoming complacent and forget about charging them several times over the winter.

I currently have four 6 volt batteries in my sailboat. They have been in the boat since 1998. I am careful not to overcharge them, equalize them several times each season, and to never leave them in a discharged state, ever.

I now own a new 5th wheel which I have removed the small 12 volt battery and have replaced it with, you guessed it, four 6 volt batteries. I have winterized the trailer and have left the batteries in the trailer for the winter.

I always check the specific gravity of my batteries before storing for the winter to be sure they are fully charged and then again in the spring before reconnecting the ground (and before charging them for the first time) to see how they faired their idle time. Once in a while, I have noticed one cell in one of the batteries to be little lower than the rest (in the spring) but they have always comeback fully after the first charge.

All the boaters at my marina now follow the same practice. The only one problem one chap had was that he forgot to disconnect the ground wire resulting in 2 frozen 12 volts. It pays to listen up and follow all instructions. As an educator, you must run into this all the time. Folks ask you for advise but don't follow all the steps.

Hope that helps Mark

Regards,
Dave