Freezing Batteries

[Dean Baumgartner]

Anyone ever tried this? I've read several articles on putting rechargeable batteries in the freezer to bring them back to life. I've tried this with the batteries on my old Makita 9.6V cordless drill. Seemed to work on 2 out of the 3. They hold a charge as well as they ever did. I put them in a plastic ziploc bag in the freezer for 2 days. The question I have is if you have done this, do you put the batteries on the charger right out of the freezer or do you let them warm up first.


Dean

[Rick Haigh]

Dean,
I am not sure what benefit that putting them in the freezer would have. Keeping them at low temperatures and then letting them warm up before use would slow down the self discharge. Typically the batteries need to be between 0C and 50C for charging. Here is a link to a very good battery site which gives lots of information about lithium ion, NIMH and NiCd batteries.

http://www.buchmann.ca/toc.asp

Rick

[Dean Baumgartner]

Rick, The benefit according to what I've read is that freezing the batteries for 2 days resets the memory and allows the battery to take a normal charge.

Dean

[Rick Haigh]

Dean,
Freezing the batteries should have no noticible effect. It sounds like a myth. It should be noted that if you charge the battery and then place it in the freezer, it will drastically slow down the self discharge. However, the battery would need to be brought back to room temp before use.

I have had the chance to talk with a battery chemist and he indicated that it is possible to increase some of the lost life by hooking them up to a power supply that would charge them at a high rate for a short period of time. This would require that you open up your battery pack and do this to individual cells. Even this would only nominally increase the useful life.

The useful life of NiMh cells is about 500 cycles (charge and then discharge) and NiCd could be as high as 1000 cycles. Many rechargable batteries will very quickly lose some capacity in the first 10 to 50 cycles.

I hope this is helpful.
Rick

[Hal Flynt]

Not sure about the myth, but it helped one of my DeWalt 12 volts and not the other. I opened the bad one and one of the individual cells wouldn't take a charge any more.

Another rejuvinator method involved "zapping" with a high voltage to get rid of "whiskers" that start to grow at the contact points or somewhere inside (can't remember the detail). This method used a large capacitor to charge up and then discharge across the battery.

I have used my auto charger and some small leads to "jolt" a stubborn battery back to life by connecting for just a few seconds and then charging normally.

I assumed that the freezer must somehow deal with the "whiskers" in another manner.

[Carol Clifford]

I know that I'm replying to something from 2004, but this info helped me and I wanted to say that, even though another drill with batteries have been purchased already, I thought I'd give the freezing batteries a try, and it worked! One already on the drill and sounding good and one is on the charger now. The best thing I found is to put the battery on the charger and forget about it even though the defective battery light is on. Then, pull the battery out of the charger, unplug it, and then put the battery back onto the charger, and plug it back in and the charging light comes on. Unfortunately, one of the new batteries became too drained to accept a charge and I didn't have to freeze it but I did have to leave it in the charger with the defective battery light on for hours and then when I pulled it out and tried it again, it started receiving a charge. Maybe this information will help someone else. I hope so.
Carol

[Cliff Rohrabacher]

did it when I was a kid. Ya get a little more out of 'em. Not much.

[Carol Clifford]

I finally got the other battery to charge up after a few more times in the freezer and the charger. I'll see how long these old rechargeable batteries last and let you know (just in case anyone is interested)