Recondition cordless batteries?

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I have a couple of cordless drills I bought a bit over 5 years ago, a Dewalt 9.6v and a Panasonic 12v. They both came with two NiCD batteries and I've been using them lightly and the batteries (it seems to me) are not holding much of a charge. Very often, when I reach for one, the battery is on the verge of dieing. Every time that happens I fetch the alternate battery and put the dieing one in the charger and that battery (again, it seems to me) charges too quickly! It's just my feeling that the "charged" signal goes on on the charger too quickly.
I know that some battery chargers feature a reconditioning feature, but of course my cordless drill chargers have nothing of the sort. I'm thinking I can go through several cycles and recondition these batteries. For instance, put the drills on Low and rubber bands around the trigger and let the motors run until I can hear the battery's losing power and then let the battery sit 5-10 minutes (maybe not necessary, it really doesn't seem hot), and then charge. I figure if I do this 4 times or so for each battery, it may well restore most of the capacity. Has anyone tried something like this?
Dan
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Dan_Musicant wrote:

Chances are after five years, it is time to replace or rebuild the batteries.
What you suggest is not exactly the same thing the company rechargers do. What you suggest worked well with the early nicd batteries in the 70's but not with today's batteries.
I suggest stopping by Batteries Plus or some like place for new batteries or have them rebuild (replace the batteries in the original case) the batteries. Unless you are getting a great deal on them elsewhere, you will likely find they have better batteries or a better price for you.
--
Joseph Meehan

Dia \'s Muire duit
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wrote:

I've had 3 battery packs rebuilt by Batteries Plus and have been very satisfied with the results. Plus they saved me about 30% over the cost of new battery packs. Red
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Also, try http://www.primecell.com/pctools.htm
and http://www.voltmanbatteries.com/
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It was normal for the charge-holding capacity of 1990s NiCad batteries to dwindle after 5 years or so. So why not make this experiment and post results here, whether good or bad?
--
Don Phillipson
Carlsbad Springs
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On Sun, 22 Apr 2007 10:22:22 -0400, in alt.home.repair you wrote:
: : :> I have a couple of cordless drills I bought a bit over 5 years ago, a :> Dewalt 9.6v and a Panasonic 12v. They both came with two NiCD batteries :> and I've been using them lightly and the batteries (it seems to me) are :> not holding much of a charge. :> . . . pur the drills on Low and rubber bands around :> the trigger and let the motors run until I can hear the battery's losing :> power and then let the battery sit 5-10 minutes (maybe not necessary, it :> really doesn't seem hot), and then charge. I figure if I do this 4 times :> or so for each battery, it may well restore most of the capacity. Has :> anyone tried something like this?: :It was normal for the charge-holding capacity of :1990s NiCad batteries to dwindle after 5 years or so. :So why not make this experiment and post results :here, whether good or bad?
I bought these drills about January 2002.
Yes, I'm doing the experiment right now. I'm recording the amount of time it takes to discharge and charge each battery during each cycle, and I figure I'll do 4 cycles with each battery.
I wish there was a way (I'm sure there is) that I could discharge them without using the motor, but maybe it's not a problem. If I knew how, I would build a discharge device, but my electronics savvy isn't great. I'm cross posting this post to sci.chem.electrochem.battery in hopes for some expert advice. :)
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There is. Solder a short pair of leads with alligator clips to a 12v light bulb and clip it across the battery leads. Use a smaller bulb, like a dome light, parking light, or tail light.
Red
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: :> :> I wish there was a way (I'm sure there is) that I could discharge them :> without using the motor, but maybe it's not a problem. If I knew how, I :> would build a discharge device, but my electronics savvy isn't great. :> I'm cross posting this post to sci.chem.electrochem.battery in hopes for :> some expert advice. :): :There is. Solder a short pair of leads with alligator clips to a 12v :light bulb and clip it across the battery leads. Use a smaller bulb, :like a dome light, parking light, or tail light. : :Red : : Hey, that's a smart idea. It would need to be a DC lamp, I suppose, and most auto lights would probably work, I'd think. Thanks.
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wrote:

Incandescent lamps don't care whether it's DC or AC applied to them. I have a 12W,12V auto bulb that's used in a Tensor hi-intensity lamp that applies AC volts to it,works just the same.
--
Jim Yanik
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I used to build and fly R/C airplanes. Conditioning NiCad batteries is a big deal to these hobbyists since a dead battery in mid-flight usually results in a mashed pile of balsa wood and about $500 down the drain. Search some of the newsgroups or hobby websites for info and good tips on theory and practice of cycling batteries.
--Jeff
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wrote:

Most drill/driver battery packs do not have terminals one can clip onto,they have flat contacts recessed to prevent accidental shorting. One would have to build a socket for the pack to plug into,with contacts to mate with the pack's contacts. Or cannabalize an old,spare charger for the socket/contacts.
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Jim Yanik
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If you're just trying to discharge it a few times, you can get away with masking, duct or electrical tape putting pressure on a chunk of wire against the contacts.
The Dewalts I'm familiar with have spade lugs that are easy to clip to.
--
Chris Lewis,

Age and Treachery will Triumph over Youth and Skill
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As I understand it, if you're going to discharge this way, you want to stop discharge just as the voltage across each cell is around 1V. Which for an 18V battery is 15V. The lamp should be noticably dimmer at that point.
Then recharge and repeat.
--
Chris Lewis,

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On Mon, 23 Apr 2007 20:36:21 -0000, snipped-for-privacy@nortelnetworks.com (Chris Lewis) wrote:

So leaving the flash light switched on over night is not best... no lamp flicker, light, nada...too much drain on the battery?

Oren
"I don't have anything against work. I just figure, why deprive somebody who really loves it."
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that it can recharge with a reverse polarity. May be possible with a single cell, but I don't think that is possible in a battery pack. There may be other new reasons for not completely discharging battery packs, but that used to be the way to prevent ni-cad memory problems. -Red
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Based on my one experience, a complete discharge is not advisable.
-- Oren
"I don't have anything against work. I just figure, why deprive somebody who really loves it."
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:
:>> >As I understand it, if you're going to discharge this way, you want :>> >to stop discharge just as the voltage across each cell is around :>> >1V. Which for an 18V battery is 15V. The lamp should be noticably :>> >dimmer at that point.:>> :>> So leaving the flash light switched on over night is not best... no :>> lamp flicker, light, nada...too much drain on the battery?:>> :>I've heard that if you completely discharge a battery it is "possible" :>that it can recharge with a reverse polarity. May be possible with a :>single cell, but I don't think that is possible in a battery pack. :>There may be other new reasons for not completely discharging battery :>packs, but that used to be the way to prevent ni-cad memory problems.:>-Red : :Based on my one experience, a complete discharge is not advisable.
I believe it is possible to reverse polarize one of the cells in a battery pack such as a cordless drill's. I seem to have read that in a post somewhere. Anyway, the manuals for the tools always seem to counsel not draining the pack too far before recharging. It's always possible that one of the cells is a lot weaker than the average and that would cause trouble. It's something that would be hard to know unless you could disassemble the cell pack, which I'm not about to do.
I haven't gotten too far in my experiment (busy today), but will get back at it tomorrow and this time keep careful records and try to determine if I'm making real progress in reconditioning my 4 cordless battery packs.
I don't think I'll bother using a slow discharge method this time. The batteries don't seem to be getting very hot while I drain them by having the drills set on low and rubber bands around the switch. I'm careful not to have the switch partially depressed. The Dewalt's instructions actually said it was bad for the drill to use very slow speed. I have no idea why. The drill itself seems to be getting a lot hotter during discharge than the battery pack, but not alarmingly so.
Dan
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Chris Lewis wrote:

As I understand it, if you're going to discharge this way, you want to stop discharge just as the voltage across *the lowest cell* is around 1V. By the time you discharge until the average cell is around 1V, or until the pack voltage is about 1V per cell, or worse, until all cells but one are below 1V, chances are good that you will be able to measure reversed polarity across the weakest cells. That's an indication that those cells are no longer cells.
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:Chris Lewis wrote: :> As I understand it, if you're going to discharge this way, you want :> to stop discharge just as the voltage across each cell is around :> 1V.: :As I understand it, if you're going to discharge this way, you want :to stop discharge just as the voltage across *the lowest cell* is around :1V. By the time you discharge until the average cell is around 1V, or :until the pack voltage is about 1V per cell, or worse, until all cells :but one are below 1V, chances are good that you will be able to measure :reversed polarity across the weakest cells. That's an indication that :those cells are no longer cells.
I agree.
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wrote:

Amen! Been there, done that.
As I read the literature, good multiple cell batteries are made up from uniform cells all from the same production batch. Then you hope they stay uniform. Best to quit using the battery as soon as you detect a slowing speed. But my wife would take a half discharged device and run it till it stopped. Hard to recover from that.
I now keep small appliances like hand vacs and grass clippers on chargers modified to trickle charge (added resistance). For frequently used tools, the slow charge might not be at all convenient but for occasional use devices, the resulting full charge adds a large margin of safety. My old Dustbuster has 10-year old cells used this way and still does its job.
SJF
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