reviving a drill battery

You might want to blast each cell in the pack. I have come to the school that at the first sign of battery trouble, I send them out to get rebuilt. It's usually not worth the trouble to try and revive them and they usually don't owe me. Do a Google for the battery rebuilder nearest you or the best deal.

how big a cap should i use? Its a 7.2 v craftsman. can i use a hi voltage transformer from an oil furnace?

No, you want to use a lower voltage/higher capacitance unit often referred to as a "computer grade" capacitor. Perhaps something like 20 volts, 80,000 uF. Charge it up to 12 volts or so and zap each cell until it will take a charge.

When you are done, the battery will give you perhaps 50% capacity for a month or two until the cells start shorting out again. I suggest that you not waste your time and just get the cells rebuilt or go out and buy a new drill set with at least two battery packs. Set one of the packs aside, uncharged, for at least a year to extend the life of your new drill before you have to throw it away simply because the batteries are bad and the packs cost more than the price of a new drill kit.

Vaughn

It works somewhat, but is a temporary measure at best. If you need full capacity, get them rebuilt or buy new ones. I had 3 Dewalt packs rebuilt by

. They perform better than the original batteries.

Randy

Been there, done that...

It's an temporary emergency solution at best.

Once the dentrites (or whatever they're called) start growing inside the cell and creating internal shorts, there's another one waiting in line out right after the one you blew open.

Nothing lasts forever...

Jeff

What with Harbor Freight (and others) often selling 12vt drill motors for less than a $20 bill, its almost come to the point where rechargable drills are a disposable item. Particularly when looking at a Craftsman 7vt drill.

I have at least two Makita 9.6 drill motors with chargers and dead batteries, and the price of the batteries alone, is more than that of an equivilent Chinese drill with more power.

Gunner

Gunner

"25 States allow anyone to buy a gun, strap it on, and walk down the street with no permit of any kind: some say it's crazy. However, 4 out of 5 US murders are committed in the other half of the country: so who is crazy?" -- Andrew Ford

I have an old skill drill that is smaller, has more torque, & is 2 years older than this piece of shit craftsman. I like to squeeze the last drop out of all my tools but im thinking that I will go buy some new cells. Craftsman outta be ashamed of themselves.

My Mikita 9.6 lost one pack - the other pack is still there.

I bought a much better one that it - and thought I might try to convert the Mitita into a power pack model. - e.g. add a cord to the one bad unit.

I really like the new one, but hate to loose a drill for just a battery.

Martin

Put it in the freezer overnight,Yes it does work!

Or just look around till you find some of the cells and rebuild your own battery pack. Measure the height and diameter of each cell and then look for comparable cells with the highest amp-hour ratings.

I am considering rebuilding a couple of my Makita 9.6v packs with NiMH cells. Should get much more capacity than the originals.

Ted

Makita 9.6V packs use standard sub-C cells which are 23mm diameter by

43mm. Panasonic list them as HHR300SCP at ~3000mAh. I would imagine other suppliers have sub-C's as well.

Ted

When zapping is polarity important?

John.

No, you want to use a lower voltage/higher capacitance unit often referred to as a "computer grade" capacitor. Perhaps something like 20 volts, 80,000 uF. Charge it up to 12 volts or so and zap each cell until it will take a charge.

When you are done, the battery will give you perhaps 50% capacity for a month or two until the cells start shorting out again. I suggest that you not waste your time and just get the cells rebuilt or go out and buy a new drill set with at least two battery packs. Set one of the packs aside, uncharged, for at least a year to extend the life of your new drill before you have to throw it away simply because the batteries are bad and the packs cost more than the price of a new drill kit.

Vaughn

Yes, observe normal polarity and proceed one cell at a time. That means that you must open up the battery pack. You are trying to blow out an internal short circuit, you know that you have accomplished that when the battery suddenly has voltage. If you were to apply the capacitor with the wrong polarity, you would charge the battery backwards. I understand that is very bad for them.

While you have the battery pack open, it would be best if you gave up on the resurrection idea and just installed new cells.

Vaughn

I couldn't figure out how to get my DW 9052 packs open without destroying them. Ended up replacing them with new cells from ebay at $15 each.

Soldering gun with the tip flattened to make a "electric knife" worked on the 4 -6 packs that I've cannibalized for the 9.6 makita drill. Pat

Try hobby shops. RC types that is.

Might get sub-c - always C and AA's and D's. The Sub-C might be used in cars. in the long packs.

Martin

Yes, but I got tired of a the rigamarole. I've found that a quick zap of each individual cell with an automotive battery charger will do the same thing.

I hook one lead to one end of the cell, then just tap the other terminal with the other lead. That's all there is to it.

Usually, it's a PITA to open the battery case and to get access to each cell. My Craftsman batter packs can be opened up by removing four Phillips screws. Handy.

Wear a face shield. Although I've never had any cells blow up on me, there's always that one chance in a million.

By the time a NiCd battery deteriorates to the point where it needs zapping, it's time to throw it away and get a new one. Zapping is only a temporary fix. If you let the battery sit, unused, for any length of time, it'll need to be zapped, again.

Been there. Done that. Many times.

Orrin