the cells in the Dustbuster are designed to be left on charge continuously.
digi-Key sell s NiCd cells expressly designed for continuous charge.
And the transformer already trickle-charges the cells.(C/10 rate)
My first DB pack lasted 10 yrs,then had the pack replaced at a Dewalt
As I understand it, you can safely discharge NiCd down to zero volts,
but no further. If you had some way of measuring each cell's voltage
individually in a battery pack, you could discharge the pack until one
cell reached 0 V. But you generally can't do this, so the "1 V per
cell" rule of thumb is an approximate way of finding a point where one
cell's voltage is diving fast.
For example, a 4-cell pack is 4.8 V (4 * 1.2 V) nominal. When its
voltage drops to 4 V, there are *probably* still 3 cells putting out
almost 1.2 V, while the weak cell has dropped to 0.4 V. Time to stop
Unfortunately, this doesn't work so well with larger packs. When a
10-cell 12 V pack drops to 10 V, you may have 9 cells still at 1.2 V,
and one unlucky cell already reverse-charged to -0.8 V. So pack
manufacturers try to match cell capacity within a pack so you don't get
one cell significantly weaker than the rest.
Also, NiMH cells don't like being taken all the way to 0 V.
I've had exactly zero luck with any cell that ever went as low as 0.8V
for more than a second or two. I've read articles by others who've had
the same experience you claim, but I've been completely and utterly
unable to duplicate it under any circumstances.
Safest way I've found with packs is to watch for a sudden small drop in
voltage. When the weakest cell gives way, it'll drop from 1.1V or
thereabouts over a few seconds to less than a volt. That'd take the
10-cell 12V pack to, say, 11.6V in a few seconds.
Music hath charms to soothe the savage breast.
That\'s why stereo has two channels.
I wasn't referring to putting a single wire across the contacts,
tho, I can see how it could be read that way.
I was trying to say that the ends of the wires connected to the
load (eg: lightbulb) can be taped to the contacts, and it will
be good enough for a couple of hours of discharge as long as you
don't yank on anything. Or rubber bands.
Take a look at the 12V versions. There's a rectangular opening in the
upper end of the battery housing. Inside the opening, there's two male
spade lugs separated by a plastic divider. When you drop the battery
into the charger or tool, the spade lugs go into a split female
You could just about plug those lugs into female automotive spade
connectors. Perhaps slightly more heavy duty ones.
It's easy to connect to the lugs with alligator clips.
Age and Treachery will Triumph over Youth and Skill
:>:> 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.
:> 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.:>
: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.
Good to know. I have a couple of tensor lamps. Thanks!
No, that's a *really bad* idea, unless you continuously watch the bulb
and disconnect it when it starts to get dim.
The problem is that the cells in the battery pack are in series, and
some are always stronger (higher capacity) than others. When you
discharge the battery into a load, one of the cells always goes dead
first, while the rest still have some energy left. If the load remains
connected, current keeps flowing, and the weak cell starts *charging in
reverse polarity*. That will soon permanently damage it.
In normal use, you hear the drop in motor speed caused by that first
cell's voltage suddenly dropping, and you switch battery packs.
Automated battery cyclers also shut off when the voltage drops to a
preset level. But the 12 V light bulb won't stop until the net voltage
across the battery pack is zero, and that doesn't happen until one or
more cells are already reverse charged.
You can safely discharge *one single cell* with a light bulb or a
resistor, but not a battery consisting of several series-connected
The usual "safe stopping point" voltage is 1 V per cell. A 12 V battery
is actually 10 cells of 1.2 V each, so it can safely be drained until
the voltage drops to 10 V. For 9.6 V battery, stop at 8 V, and so on.
I don't know about reconditioning them, I agree with Joe, they are nearing the
end of their useful life. I have heard many good things about Voltman's
rebuilds. I haven't used them myself yet but it won't be long before I do.
My Dewalt 18 volt batteries are 2 years old with heavy use, and they are
definitely not as good as they used to be. The higher the voltage (and the
current draw), the faster they wear out, mainly due to internal heating
according to what I have read. I use my cordless reciprocating saw a lot, and
it discharges the batteries much faster than the drill, so I suspect that
contributes to an early decline.
On Sun, 22 Apr 2007 09:42:07 -0500, snipped-for-privacy@SPAMwowway.com (DT)
:I don't know about reconditioning them, I agree with Joe, they are nearing the
:end of their useful life. I have heard many good things about Voltman's
:rebuilds. I haven't used them myself yet but it won't be long before I do.
:My Dewalt 18 volt batteries are 2 years old with heavy use, and they are
:definitely not as good as they used to be. The higher the voltage (and the
:current draw), the faster they wear out, mainly due to internal heating
:according to what I have read. I use my cordless reciprocating saw a lot, and
:it discharges the batteries much faster than the drill, so I suspect that
:contributes to an early decline.
I'd think that quick charging would contribute to decline faster than
fast discharge, just based on all the stuff I've read, and there's
plenty of that.
5 years, I think, with modern NiCD technology is not necessarily all you
can expect from them. I have some 10 year old NiCD's that I just
reconditioned to 80% + capacity according to my La Crosse BC-900
charger. I think a lot depends on the quality of the batteries.
I'm hopeful that my reconditioning regemin described will restore these
batteries to 85%+ capacity. They may have acquired some memory, and I've
never done any kind of conditioning cycling on them.
Your batteries are shot, you'll never get the capacity that you once
The name of the game with cordless tools is to "use 'em or lose 'em."
I've had 18 volt Milwaukee batteries last over 10 years with almost
daily use, maintained per manufacturer's instruction's. Let them sit
unused for a couple of months and any brand battery will be ready for
the trash. If you do not use cordless tools a lot, try drilling some
holes in a 2 x 4 with a paddle bit once a week to drain the battery,
then after it cools off 10 minutes or so, recharge it. That way it
will always be ready to go and the batteries will last much
longer.........or, like I said, use it more often.
:> 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?
:Your batteries are shot, you'll never get the capacity that you once
:The name of the game with cordless tools is to "use 'em or lose 'em."
:I've had 18 volt Milwaukee batteries last over 10 years with almost
:daily use, maintained per manufacturer's instruction's. Let them sit
:unused for a couple of months and any brand battery will be ready for
:the trash. If you do not use cordless tools a lot, try drilling some
:holes in a 2 x 4 with a paddle bit once a week to drain the battery,
:then after it cools off 10 minutes or so, recharge it. That way it
:will always be ready to go and the batteries will last much
:longer.........or, like I said, use it more often.
Well, I've been having good success reconditioning some old NiCD
batteries using my La Crosse AA and AAA charger, so I figure that using
the same technique with my cordless batteries I may be able to restore
them as well. It's different, in that the cordless batteries are really
several batteries, presumably connected in series. I don't think the La
Crosse charger is doing anything fancy. It's just charging, then
discharging, then charging again, then discharging, etc. until the
measured capacity of the battery (determined during the discharge cycle)
is no longer increasing and then it terminates the process. I can do
this sort of thing manually -- i.e. run the cordless down until it's
losing power, charge, and do it over and over until the measured time it
takes to charge and/or discharge is no longer increasing. Perhaps I can
restore a large part of the lost capacity of the batteries doing this. I
figure it's worth a try. Anyway, I'm not yet seriously inconvenienced by
the loss of capacity of the drills because I have a 2nd battery for each
one. I figure if my technique works, using it occasionally (every year
or two) will go a long way to maximizing the overall battery life. I
hear that buying replacement batteries for these is pretty expensive
(they stick it to you).
You are wasting your time. Throw them away and buy new batteries.
I took mine apart and replaced the shorted 1.2v cells with new cells,
but it is not worth the effort - although the new cells are 2600mha
and the ones I replaced were 1300. Sure, I have a much more long
lasting more powerful battery now but it just ain't worth the effort.
Agreed that you should replace all the cells at one time for reduced
effort. The 2600 mha batteries are physically a bit larger than the
1300's. How'd you get them to fit in the battery case? Wouldn't work
in my DeWalt battery cases.
Sure they would fit. At least well enough. Very little difference
in size and so what if the case doesn't close properly. The battery
pack just hangs there, it is not important that it have any structural
integrity. The diameter is the same, but the length is different and
altho a tight fit, mine fit and the case screwed together just fine.
I went ahead and bought some NiMh 3300 mah batteries for the next
device I have in the house that craps out so am anxious for something
else to fail. I may go find that hand vacuum I tossed in the garage.
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