New Battery won't charge

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I have a three year old Compaq Presario 2715US.  The optional "bay"
battery was, apparently dying.  It charges, but is, according to the
battery meter in the laptop, fully discharged in under an hour.

I bought a new battery and it would not charge at all.  Within ten or
fifteen minutes, the charging light would flash indicating a charging
problem.  I sent the battery back and got a new one.  Same problem.
However, I point out that the old battery still does charge, so I am
not suspicious of the charging hardware.

I have read numerous posts that really, really dead new batteries may
not charge because new modern laptop charging systems can't "talk" to
the battery at the beginning of the charging cycle and may refuse to
attempt to charge them.  I suspect this is my case.

How can I get past this "won't charge first time" problem?  I read
someone sort of "jump started" his new battery by charging it from
another lead acid battery.

Does anyone know about a Presario bay battery pinout?  How can I
charge this battery if the laptop won't do it?  Is there some sort of
external charger for laptop batteries or must they be charged by
inserting them in the laptop?

Re: New Battery won't charge

  Charging board issues are common on the 2700's as well as quite a few
other compaqs.. We can offer a free asessment of the problem if you need

Re: New Battery won't charge

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Whilst I don't know what type of battery your system uses, it sounds
suspiciously like a Lithium-Ion.  If any individual cell's terminal voltage
drops below 3 volts per cell, the charger will refuse to charge it.  This is
entirely by design.  It may be that the battery has been stored for too long
before being supplied to you (a common scenario).

You should make no attempt to 'jump start' it, particularly as you have no
idea how long it has been in this state[1].  The refusal to charge is
because the cells develop an internal short circuit once the voltage drops
below 3 volts, which becomes more severe with time.  This short can cause
the cells to explosively deconstruct if charged.  The flame from the rupture
point cannot be extinguished as the cells generate their own oxygen.

[1] It can be possible to 'jump start' batteries if they have been in this
condition for very short periods of time (like a few days), though no
manufacturer will recommend it (and neither do I).  If you do this, or know
someone else who does, it is imperative that the batteries are kept
somewhere for at least 24 hours where any fire will do no harm.  The
batteries must be at least 6 feet from anything that will burn.  If the
batteries refuse to charge after this, then the short is severe enough that
the battery must be discarded.


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