Does it really help batteries last longer if you keep them in the fridge? If it does, why and how does this work?
Most chemical reactions are slowed down by colder temperatures. Since the self-discharge of a battery is chemical in nature, putting the battery in the fridge will slow that down, making them last longer.
You might not want to use the freezer, though. Depending on the battery, and your freezer temperature, you might freeze the electrolyte.
Also, you don’t want the batteries to be cold when you actually use them- a cold battery has a lower capacity than a warm battery, for the same reason that a cold battery will self-discharge more slowly. So it’s best to warm them up to room temperature before using them. As someone else mentioned the last time this topic came up, be careful not to let condensation form on the batteries- at the very least, wipe the terminals off after they’ve warmed up.
In this thread, I replied that Consumer Reports says it make very little difference in shelf life.
These theories are true, for alkaline batteries. Eveready, Duracell, etc. They do not hold true for Nickle-Cadmium rechargeable batteries.
Ni-Cads are extremely succeptible to drain of charge due to cold. I have to take a small hand-warmer to my batteries in order to get decent run life out of them.
If not kept warm, a battery pack will lose it’s charge in a few hours instead of a lot of days. I’ve done overnight shoots in the city in the winter where I’d not been able to find a close-by place to keep the battery packs warm, and had been s.o.l. by about 3am. ( The packs I use are 14.4 vdc, 5ah- but the theories apply to any Ni-Cads ).
[This Site](http://www.antonbauer.com/handbook/handbook.html#COLD CLIMATE PRECAUTIONS) from the Anton Bauer Company shows in exhaustive detail the discharge rates and effects on power availability on batteries that are exposed to cold. The Battery Manual is an invaluable tool in assessing dc battery power needs in remote areas.