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OT rejuvenating cordless drill batteries

Joe Miranda

Titanium
Joined
Oct 19, 2004
Location
Elyria Ohio
As a last try before buying new batteries (at about $40 a pop) I put one of my 14.4v batteries from a Ryobi rechargeable drill on my car battery charger. I left it on for about 3 hours and checked to see what happened. Lo and behold, the battery took a charge and has held up to a pretty aggressive test. I am going to keep testing but the preliminary results look promising. Have any of you tried something similar and if so what were your results?

Joe
 
I used to deal with hundreds of two way radio nicads. We had a special charger that would charge, discharge and measure the capacity. Some batteries that appeared to be almost gone would show a great improvement. The sucess rate was maybe 50%. There are a couple of companies that will take your old battery and put new cells in it at a considerable savings.
 
It's a service some of the local stores provide. I heard via a mail flyer from the store near me (Lake Zurick, IL). Sorry for any confusion. I gave the website so anyone interested could find a local store. No affiliation, just happy with my much improved batteries.

John
 
I rebuild mine.
Use a large soldering iron, so the tab/jumper is soldered before the battery innards know about the heat!
 
How about the cases? I have a 14.4v Makita battery that was dropped. Still works, but the clips are gone, so I have to tape it in all the time. Batteries are 100%.
 
I am a cheap bastard,so 60 bucks for a Makita pack for an old drill wasnt going to happen. Drill was fine, batteries were toast. Broke down and bought a Dewalt. One day in Horror Fright saw 18V packs for $9.99. Opened everything up and replaced the cells in the Makita packs with the HF ones. I gotta say they are as good as the originals. Two new packs for $10. I am such a cheap bastard. :D
 
OK. Here is the result of my continued testing. The first battery that I tried worked very well. I was extremely pleased that I was able to get a full 14.4v charge into it and it has lasted for several hours so far with some pretty heavy useage. I was so pleased I took the other battery which was completely dead (no voltage measured with a multimeter) and hooked it up to my car battery charger for about 1/2 hour. I went and got it to see if it had blown up and the battery was slightly warm to the touch - a good sign I thought. I checked the voltage and it was at @ 14.6v. I put it in the drill and it is working better than the first one which I had charged for a longer period. We use these things pretty heavily throughout the day so it is a good indicator so far that it works.

I also have a 9.?v black and decker that I bought at a garage sale for $10.00 which had one bad battery. I thought I would give it a try. I hooked it up to my charger for about 50 seconds and it got warm that quick. I went and measured the voltage and it was about 8.5v. Pretty good! I put it in the drill and so far it seems to be working as good or better than the other battery.

This is my experience. One of the sparkies on the site may be able to give a detailed explanation why this works but it does work! We'll see if I did any serious damage to the batteries as time goes by but the thing is - these batteries were toast anyhow! They would not take a charge at all. My plan is to use the regular battery charger until their performance runs down again and then give them a zap with the car charger. This may make a lot of aftermarket battery sales people very unhappy.

Joe
 
Joe:

As part of your experiment measure the voltage across the battery at the start, middle, and near the end of your charging cycle. Also measuring current would be useful.

.
 
I was building crates yesterday and thinking about how far these things have come in 20 years. My first rechargable was good for screwing on electrical wall plates and that is about it, my Makita 1/2 inch is just about a perfect tool, I use it several times a day. I even use it to scrub our slate kitchen floor.
 
OK, what I think you're doing here is blowing off the whisker filaments.

NiCd batteries tend to die by electrochemical action - whisker filaments form that internally short the cell, causing loss of charge capacity and eventual complete loss.

What we used to do with radio battery packs was to disassemble them and find the defective cell - then this got a faily beefy capacitor discharged across it to blow out the whiskers.

Worked pretty well though not in all circumstances.

Your approach is similar though to be honest it gives me the willies - any heating of a battery is a bad idea, because a blocked vent can cause a cell to rupture - and that can get ugly.

Just .02 from an ol ex-electron herder...

Alan
 
Alan,

So you don't think that holding the battery in your hand until it is warm to the touch is the safest method?
 
Hunted this thread down and tried the above mentioned procedure. Had two dead batteries. One of the two was revived using this trick. I have a 7.2V battery and applied 12 volts for maybe 5 minutes and then reduced to 9 volts for 15 or so minutes. Seems to have a full charge now. This saved me some time because the battery is for a rotary shear and not easily found.
 
JL Sargent,

Since my original posting I have tried this on numerous occasions - all with the same result - it works! After about a month I have had no problems with any of the batteries that I have experimented with.

Joe
 








 
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