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Re: OT: reviving a battery

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On Tuesday 03 September 2002 11:20 am, Stephen Ryan wrote:
> On Tue, 2002-09-03 at 13:58, martin f krafft wrote:
> > high folks,
> >
> > Excuse this off-topic post, I have yet again the desire to profit from
> > your wisdom...
> >
> > I have a couple of batteries for my Dell laptops. Some of these
> > haven't been in a system for months. Now I check one after the other,
> > just to find that two of the batteries seem dead. APM (as well as the
> > Dell BIOS) indicates 0% charge but status "Charging..." and yet, not
> > even a tiny percent was added to the charge over the last two hours.
> > It's still at 0%.
> >
> > Do you have any hints on what I could do to revive these batteries?
> > I just can't believe that they die because of lack of attention...
> FWIW, I've had the same problem with a Thinkpad battery; a replacement
> battery exhibited the same symptoms soon after purchase.  IBM support
> diagnosed it as a failed DC-DC converter board but then redirected me to
> a non-existent local service to have it replaced.  :-(

Amateur radio operators (hams) run into this often.  It is critical to tend 
to all NiCD,  NiMH, and Li-ion batteries monthly.  If you drain (discharge) a 
battery, let it fully cool, then get it on a charger without delay.  I make 
it a point to rotate all my batteries to keep them both fully charged and in 
good condition with intended use loads.

Letting a battery stand too long (<30 days) will always discharge the 
battery.  The least prone to this effect is the typical non-rechargeable 
alkaline batteries.  Car batteries, RV deep cycle batteries, and of course 
laptop batteries do need charged whether you use them or not.  Prolonged 
negligence will always damage them, after a while, the damage is too much and 
many newer chargers won't even try to charge them (that's when the little red 
light starts blinking on the laptop).  Also over discharging a battery can 
cause polarity reversal, this is caustic to the remaining cells in the pack. 

Further, if you have the newer Li-ion type batteries, don't interrupt a 
charging cycle.  No, they will no longer explode, but they will begin to 
degrade.  When it's time to charge it, make sure it is fully charged without 
interrupting your charging source power.

If you really want to attempt a salvage, then you will need to learn how the 
cells are packed and where each lead goes.  I would definitely determine if 
you have reversed cells, if so, will, good luck.


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