*
One of two 12 volt battery packs from my factory refurbished cordless
Ryobi drill recently failed.A 24 hour recharge yielded hardly 15 seconds
of work.Finding that a new 12 volt battery pack was from $34 to 49
dollars gave me impetus to dissect the bad battery pack.
I found in it 10 smaller batteries,each that when charged should
yield 1.2 volts.Ten small batteries when charged yields 12 volts.My
digital mutimeter confirmed all but one to be fully charged.That one
battery held less than .4 volts.I reasoned that this battery had failed
and shorted the remaining series of batteries.My Radio Shack catalog
advertised two batteries that appeared to be replacements.The one I
chose was #23-190,a package of two batteries,at $7.99
I tried desoldering the bad battery from it’s connector but was
forced to use wire cutters.I salvaged as much of the electrical
connector as possible to both sides of the unit.I then prepped both
sides of the replacement battery with sand paper and flux and soldered
it between the other batteries.Then back to the charger.
Twelve hours of charging yielded 13+ volts;the same as my other
pack.So far I,ve gotten 2 hours of work out of the renewed battery
pack.All at a cost of about $4.Hope this helps some of you on a low
budget!!
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Replies
*
And I just threw out two defective Dewalt packs I was gonna get around to taking apart someday.
*Don,Buy a new one.Then get on with your life.Ed. Williams
*You know, Ed., I thought about telling him the same thing. Then I realized that I admire a man repairing a battery pack- I used to do that sort of thing all the time until I got so busy getting on with my life.
*lonecat,You make a good point. But the motive matters. If you are spending all that time to save thirty bucks, it is a false economy. If you are spending that time because it is fun and rewarding, then go for it!Rich Beckman
*I'd never waste my work day doing it but for some reason, it seems like a good idea to do it in front of the TV in the evening. My rates are lower at night.
*Those battery packs are so over-priced that from now on I will do it out of principle--don't forget about the environmental cost of throwing away 9 battery cells because one is defective- add that to the thirty dollars.Dave
*
I would like to know more details about finding out which battery cell is defective.
*
lonecat,
Yeah, and I do remember what it was like not to have two nickels to rub together. I hope never to be in that spot again. Sorry, I forgot where I came from.
Ed. Williams
*Test across each cell with a volt meter. The bad cell will read low voltage or will be short circuited.
*But make sure before you test the individual cell that it is not electrically connected to any other cell. Otherwise you are really testing all the connected cells.To electrically disconnect you must break either or both of the positive or negative connections.
*All the batteries in these packs are in series, testing one with the others still connected won't make any difference.
*Let's see now: I have 9VDC on the pack with all batteries connected when I should have 12VDC. Which cell is bad? Breaking them apart and checking each one will tell me that. Also, in NiCd packs it is not all that uncommon for one cell in the pack to reverse polarity while the others do not (as a matter of fact I am looking at one where that is the case). Can't tell that with them all together.You can only check the electrical characteristics of a single cell by making sure you are only checking that cell.
*Fred,Ryan is right. If the batteries are all in series you can check them while they are connected to each other. Try it both ways to convince yourself.Jerry
*
I have actually made a couple battery packs from scratch. It took me a couple weeks to mold the plug ends, design a case and hook up the wiring. I didn't put a thermistor (this tells the charger to turn off once the battery heats up) in one, and ended up melting the charger. I used surplus store cells since the cost of new ones from radio shack is a lot more than a new pack. Like climbing a mountain because it's there, I'm glad I did it, but found myself questioning my sanity and wishing I'd just bought a new pack by the end.
I've also repaired packs by just changing a cell or two. The problem is that if the whole pack is old or well used, other cells are going to start dying. I'd still try replacing a cell once, but if you're starting to put $16 into a pack that still might die again, I'd rather put it into a new pack that should perform well for another few years.
*
One of two 12 volt battery packs from my factory refurbished cordless
Ryobi drill recently failed.A 24 hour recharge yielded hardly 15 seconds
of work.Finding that a new 12 volt battery pack was from $34 to 49
dollars gave me impetus to dissect the bad battery pack.
I found in it 10 smaller batteries,each that when charged should
yield 1.2 volts.Ten small batteries when charged yields 12 volts.My
digital mutimeter confirmed all but one to be fully charged.That one
battery held less than .4 volts.I reasoned that this battery had failed
and shorted the remaining series of batteries.My Radio Shack catalog
advertised two batteries that appeared to be replacements.The one I
chose was #23-190,a package of two batteries,at $7.99
I tried desoldering the bad battery from it's connector but was
forced to use wire cutters.I salvaged as much of the electrical
connector as possible to both sides of the unit.I then prepped both
sides of the replacement battery with sand paper and flux and soldered
it between the other batteries.Then back to the charger.
Twelve hours of charging yielded 13+ volts;the same as my other
pack.So far I,ve gotten 2 hours of work out of the renewed battery
pack.All at a cost of about $4.Hope this helps some of you on a low
budget!!