Something I have noticed about batteries that freeze;
1. Sometimes it is a real disaster and they split wide open and dump all the acid out.
2. Sometimes they survive just fine. I have numerous instances of batteries that have frozen and thawed and refrozen numerous times with no apparent ill effect. Some of these were "deep-cycle" but most were ordinary "wet" batteries.
Probably the most amazing case involved a pair of 6 volt batteries in a '59 Jaguar sedan I bought for parts. The car has sat outside for 10 years and where I live the batteries probably experienced at least 20-30 freeze thaw cycles. I took these batteries out and put my 1 amp unregulated charger on them. After a couple of days I noticed they were "gassing" nicely, so I took the charger off. A few weeks later I needed a 6 volt battery for a car, so I stuck one of these in. Cranked the car right up and I'm still using it.
I have a theory, but let's hear yours.
I don't know how cold you're talking about, but I have never had a fully charged battery with the correct fluid level freeze as cold as I have ever seen it get (-44). If I did ever have a battery freeze, I would be worried about the freezing breaking cells and plates. Even on frozen batteries, I have never seen a case break.
Could be A; the material the battery's were made of or B; they had just enough charge in them to keep from freezing.
Even here in Portland Oregon, battery sitting outside, case broke. But I am talking about a 12 volt battery.
I have recharged frozen batts. and they seem to be ok. only a dead batt. can freeze the important thing is dont try to charge or jump a frozen batt. it can blow up in your face!
I am quite sure that the battery that sat outside for 10 years was dead. Like you I have never had a fully charge battery freeze.
OK so my theory;
A lead acid battery that sits for a extended period of time goes dead. Batteries in this condition seem to survive freezing.
Whereas a battery that is drained by something hooked onto it (light or whatever), seems to not survive as well.
But here is where that seems to break down. Modern cars have lots of "little drains" (digital clocks, remote entry systems).
Touch wood, I have never had a battery break on me from freezing, and over the years I have had a number of them freeze.
And yes I never try to charge them frozen
Les, I did have the battery in my Escape freeze a winter ago due to low water in one cell. It was dead as a door nail. Now I am not sure it froze all the way through, but I could see ice in all the cells. I trickle charged the battery until it thawed and then refilled the low cell. It does hold a charge, but it is definitely weaker than it was before. Don't think it will make another winter. The old tractor batteries that I did see freeze, bulged some at the sides, but didn't break.
I'm thinking the best way to avoid frozen batteries is just to move to someplace warm.
When I was a kid my dad used to hang a trouble light under the hood of everything we owned. Our tractor was in the barn and he threw a tarp over it with the light. Even at -30 that thing would always start. Forget the light and the tarp and at -30 you would have to wait for a warmer day.
Those who decided they knew what we need when they outlawed the 60 watt bulb have never had to rely on the good old bulb for heat. I wonder how many batteries, well pumps, baby chicks, pipes, etc., have been saved by the evil 60 watt bulb.
You got that right Gary, and with a 60 watt bulb you don't have to smell all of that burning human flesh like we do when we have to use the 75 watt bulbs.