NiCd Battery Help Needed

[Charlie Barnes]

I've been reading this forum for several months (it's great), but now I actually need some advice.

Here's the deal. Both of my 4-5 year old 18V Milwaukee cordless drill batteries have suddenly "died" in the last 2 months. They won't take a charge at all. When the first one went out, I purchased a new one which works fine so I know the charger is OK. The second old one died right after I got the new battery. My situation is that my tools see occasional heavy usage, but sit idle much of the time.

Since buying replacement batteries is kind of expensive, I was reading up on some posts on another site about some methods to rebuild the battery packs. Most methods seem to recommend taking the case apart and checking the cells progressively until one is located that is substantially under 1.2V. I have both old battery cases apart, but I don't get any voltage at all when I check the individual cells. Zero.

Does this mean that all of the cells are bad?
Is there some other method of checking whether a cell is good or bad? (Remember, I can't get either pack to charge at all.)
Any other suggestions short of buying 15 new cells for each one? (In which case I may be better off just buying another new pack.)
I have read many conflicting opinions, including NASA's, on how to prolong NiCd battery life. Most of the recommendations are geared towards commercial applications and involve some high end charging equipment. What's "the truth" on this from a practical perspective?Charlie

[Mike Cutler]

Charlie. First off. If I've never done so before, Welcome to Sawmill Creek.

It's really odd that you are getting zero on every cell. Do you have the ability to check your meter against a "Known" good source. A Transistor radio battery, or maybe a triple A battery for computer peripheral?
You should be seeing something, even if you were using a digital meter, instead of an analog like a Simpson 260.
I think that you will find that even if you did replace all of them, it would still be cheaper that buying a new battery from Milwaukee. Last I checked those batteries were $70-90 bucks. Hopefully they are not that expensive any longer.
Good luck.
PS. Maybe your meter on it's lowest setting isn't sensitive enough to see these voltages on the DC scale?

[Randy Meijer]

Rebuilding battery packs at home is sort of tricky unless you know what you are doing. You need the correct test equipment and proper replacement batteries among other things. Your best bet is to find a commercial place that rebuilds those puppies. Won't be a problem if you are close to a big city; but probably not an option if you live in the country. If your current battery pack is 5 years old, all of the cells are at the end of their normal life so the best bet would be to replace all of them.

P.S. There as a detailed discussion of this issue not too long ago. Try using the search function to locate that thread. There will be some good information that should be of use to you.

[Ian Abraham]

With 5 year old packs you are probably going to have to replace the whole set anyway. Even if only one cell is actually dead, the others will probably be in their final days anyway.
Wether it's worth it depends on how cheap you can pick up a set of new cells, but obviously companies are rebuilding them cheaper than you can buy a new one, so it should be economic.
Nicads are fairly forgiving to re-cell, the newer technologies have a habit of exploding if the cells dont match the charging circuit, so keep away from them.

Cheers

Ian

[Charlie Barnes]

Thanks for the thoughts guys. Just to respond to a couple of the questions raised, I'm using an older analog multimeter that I've owned for about 15 years. I was using it set on the 3V DC scale. I still get zero even when I take it down to the 0.6V scale. Also, a new battery checks OK, so I know it's not the meter. I did get a link forwarded to me from another site, www.primecell.com (http://www.primecell.com), that looks interesting. As I read it, they want $48 to rebuild an 18V pack with NiCd or $72 to rebuild with NiMH (plus shipping in both cases). Buying individual cells is going to cost around $45 plus shipping. I can get a brand new battery pack for around $55. I think that's the option that I'm going to choose. Thanks again for the thoughts.

Charlie

[Steve Clardy]

Contact Jason for prices. He did 5 of my PC batteries at a terrific price.

http://www.batteryrebuilders.com/