If you were Registered and logged in, you could reply and use other advanced thread options
|
Posted by Dan_Musicant on April 24, 2007, 12:41 am
:
:>
:>:
:>:>
:>:> 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.
:>
:
: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!
Dan
|
 
| |
Posted by Dave Martindale on April 26, 2007, 12:07 am
>> 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.
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
cells.
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.
Dave
|
|
Posted by DT on April 22, 2007, 10:42 am
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.
http://www.voltmanbatteries.com/
--
Dennis
|
|
Posted by Dan_Musicant on April 22, 2007, 11:48 am
On Sun, 22 Apr 2007 09:42:07 -0500, dthompson4389@SPAMwowway.com (DT)
wrote:
: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.
:
:http://www.voltmanbatteries.com/
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.
|
|
Posted by volts500 on April 22, 2007, 1:18 pm
> 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
Your batteries are shot, you'll never get the capacity that you once
had.
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.
|
Page 6 of 7 < 1 2 3 > last >>
| Similar Threads | Posted | | Re: Any value to dead "cordless" batteries?! | June 13, 2005, 8:16 am |
| Re: Any value to dead "cordless" batteries?! | June 13, 2005, 11:52 am |
| Re: Any value to dead "cordless" batteries?! | June 13, 2005, 2:32 pm |
| Charging Cordless Batteries in a Car | June 9, 2007, 8:16 am |
| Has anyone repaired cordless tool batteries | March 5, 2006, 4:54 am |
| sears cordless tool batteries | November 3, 2007, 9:02 am |
| Re: self-made charger for cordless drill batteries | December 30, 2005, 3:09 pm |
| Cordless power tool batteries deteroriate with time? | February 19, 2007, 8:14 pm |
| Speaking of cordless drill batteries - Milwaukee recall | October 23, 2007, 10:48 am |
| Batteries | March 16, 2007, 1:29 pm |
|
|
Yahoo! 
Google 
Windows Live 
del.icio.us 
digg 
Netscape 
XML Sitemap