Batteries Myth or Fact

[John Bacon]

In the days when you could go into a garage and find a cat sleeping in the old oil stove the floor was never above freezing in the winter and if you put a warmer battery on the cold floor it would weaken the battery by cooling it. Check it out they say store your battery cold but not below 32deg. The chemistry of a battery makes more power when warm than cold that's why they are rated in cold cranking amps at 0deg and cranking amps at 32deg and marine cranking amps at 80deg. If say a mechanic in 1950 took the battery out of a car that won't start in the winter and left the weak battery on the cold floor chances are it would weaken more if not freeze. Anyway this is where the myth came from, its not the cement its the extreme cold that weakens a battery.

 

While it is true that cooling the battery will reduce the amount of current immediately available; it actually prolongs the life the of battery (assuming that it doesn't freeze which according to another post occurs at -60 for a fully charged battery). Since the post is about storage not about how to maximize the power for immediate use; the cold is actually beneficial.

[Fisherman]

Interesting.

Okay let's say for the sake of argument you're storing two batteries, one inside, the other outside.

Both aren't topped up.

Will both survive?

No problem, for your question, I'll say that both of your batteries have been depleted to.. say 50%.

The battery that is stored indoors will survive a bit better not being subjected to freezing, the battery left outside in the freezing cold will most likely freeze solid by the time you hit -20C and then be physically damaged..no revival.

Now to go a bit further, when you leave batteries inactive (not on a maintenance charger for long periods such as over 30 days) they begin to sulfate,(chemical reaction) the slow steady reaction of the acid on the plates causes the plates to get a crystalized coating on them and it is really difficult to reverse that reaction. I know some of this stuff sounds like making yeast bread to some, but, go to the VDC Electronics site for some reading. Heck I've still got a 12V7A Gell cell from about 15-16 years ago when I used my F/F without having a big battery in the boat.

What John Bacon said above is true, the cold just slows down the chemical reaction that "makes" the power when you turn the key.

Edited May 5, 2010 by Fisherman