Rechargeable batteries

[MiamiCuse]

I got a cordless drill from DeWalt on a big sale two years ago I remember it was on some clearance for $129.95 or something and it came with two batteries.

Now the batteries will charge up in 30 minutes but will drain in much shorter time. I checked for new 12v ones and they are $70 a piece! I could not believe it.

So, first, is there anyway to "fix" the batteries. I assume they are draining must faster because I did not wait till they are totally drained before recharging or I left them on the charger for too much longer after it was charged? Is there a way to fix the problem other than getting new ones?

MC

[Edwin Pawlowski]

Batteries have a finite life. The cells are going bad and not holding charge. There are rebuilders that will do them cheaper than new and can also upgrade to more powerful.

I've used these guys

with good results but there are others.

[dpb]

MiamiCuse wrote: ...

As Edwin says, take the packs to a rebuilder. Yellow Pages is bound to have quite a number in a place the size of Miami metro area...

As for causes, your surmises may (or may not) be correct. Better chargers have self-limiting circuitry that senses the batter is fully charged and shuts off so as to not overcharge them--cheaper ones may not or not effective. So, depending on the charger, leaving them on it for long periods of time could be a contributing factor.

Some chargers simply do a better job of charging than others--they sense charging rate, etc., and are designed such the the charging cycle matches the particular type of battery. Again, others don't.

Lastly, of course, there's simply the type and quality of the batteries themselves...

--

[MiamiCuse]

OK thanks, I will check them out.

[do_not_spam_me]

If you're lucky, you have nothing worse than some cells that have reversed in polarity, and they can be corrected by charging each one individually by applying a current of approximately 50-200 mA for a few minutes and then immediately charging the battery normally. Shorted cells can usually be fixed, at least temporarily, by applying some brief pulses of high current at about 30-100 volts from a capacitor, but it's likely the shorts will grow back in a day or a week. I've taken the good cells from a pair of identical faulty battery packs to make one good pack. The cells are best attached with a spot welder, but with a high power iron and some rosin flux, the cells can be safely soldered together, if you work fast enough to prevent overheating them. When repairing a battery, use only identical cells so each cell carries the same load. Cells vary in type (nicad, NiMH), capacity (a sub-C cell can range from 1,000-4,000 mA-H), and impedance (usually because some cells have plates made of foamed metal, others of sintered metal).

[hallerb]

ece! =EF=BF=BDI could

they put all new cells in your old pack, works great

[Tom Horne]

Google battery rebuilding. There are folks that rebuild tool batteries for a comparatively modest price.