deep cycle batteries in cold weather

[ofer]

I have a few 6V batteries in the lazarette and it's not heated.
Boat is stored on the hard in South central Alaska. Not too cold in Alaskan standards.

some say they can freeze others say should be no problem if batts are fully charged.

Not sure i can remedy the situation this winter.

I am trying to figure out what happens when a battery freezes. are there any visual signs? or the plates inside just go bad and i have to perform some testing on each batt to determine its health.

at what temps do I need to be concern?

 

[Comodave]

Our last boat was stored every winter indoors unheated for 6 years. We kept the boat plugged in a lot so the batteries stayed charged and we never had any problems. If the boat was not going to be plugged in a lot then I would charge the batteries every 4 to 6 weeks.

 

[rslifkin]

If they're fully charged they have to get extremely cold (way below zero) before freezing is a concern. If they're low on charge they'll freeze more easily (and sulfation will be a concern).

 

[kthoennes]

Our marina disconnects all the batteries for winter layup so they don't slow drain (or at least not as fast). Lead acid, 12v. Our winters sometimes beat Alaska (well, Anchorage anyway, maybe not Fairbanks). Not unusual to drop more than 20 below zero. Hit almost 30 below last winter. As long as I'm conscientious about checking water levels, we'll get around five years out of our batteries.

 

[Jeff F]

These are essentially the same batteries that have been used in automobiles and machinery for generations. They won't freeze if charged.

 

[psneeld]

https://www.google.com/search?q=col...msung-nf-rev1&sourceid=chrome-mobile&ie=UTF-8

When it comes to the cold electrolyte in a fully charged battery can withstand temperatures down to -33°F (-36°C) before freezing. When fully discharged the electrolyte is basically water so it will freeze at 32°F (0°C).Sep 13, 2019

 

[Bacchus]

Ofer
Good info above and have stored many battys over winter w/o problem.
The keys are fully charge and disconnect to avoid parasitic draw that can easily run a batty down in a relatively short time... a week or 2 in some cases.
Frozen battys will generally bulge the case and sometimes split or leak which is a mess to clean up.
Do not hook at charger to a frozen batty.
I have switched to AGMs in my boat as I can't remove or charge them in storage but I do charge fully and disconnect. When I've checked every spring before reconnecting they are at 12.5-12.6 V even after 7 seasons of use.