[ltp] Reforming Confused Batteries

[Joachim F. Selinger]

Hi Les!

On 14 Sep, Les Bell wrote:
> After reading the discussion over the last few days, I decided to try
> the procedure to see if I could fix up the battery in my 600e, which
> appeared to be losing its mind. For the first half of this year, I
> travelled very little, and so the system was permanently plugged in,
> with the result that now, the system would give only 25 minutes battery
> work time.
> 
> So, I discharged the battery to the point where the system would
> suspend, but found that the battery was still giving over 11 volts.
> Since the system would now not restart, in an attempt to deep discharge
> the battery, I placed a 390 ohm resistor across the battery terminals
> and left it. Three hours later, it was still showing over 11 volts. So I
> left it (to go to a rehearsal for the Sydney Olympics opening ceremony -
> don't miss it!) but when I came back seven hours later, the battery was
> fully discharged - to 0 V.

This was definitely not a good idea. Whoever recommended was not so smart.
You should never ever deep discharge a battery. Just make sure you get it
off the discharge when it hits the steep voltage drop. That is enough and
any sensible microcontroller discharger would do just that.
 
> Now, the battery won't even *start* to recharge. When the AC adapter is
> plugged in, the battery status indicator just blinks orange, goes solid
> orange for about two seconds, and then goes black to blinking orange
> again. I measure 0V across the battery terminals after leaving the
> machine 'charging' overnight.
> 
> Does anyone have any suggestions on how to 'kick-start' this battery
> again? I'm beginning to think these batteries are too smart for their
> own good, but with IBM dealers quoting me anything up to $A400 and a
> minimum of one month delivery for a replacement, I'm willing to invest
> considerable effort in trying to reform this battery.

You should use a power supply with adjustable current to start charging it
a little until it reaches some meaningful voltage, maybe 5-6V? just
connect the + of the power supply to the + of the battery and - to -.
Pay attention to watch the voltage while charging it with maybe one 10th
or even better one 20th of the capacity in Ah (e.g. 2000Ah -> 100mA
current)

Once you reach the 5-6V you can hook it to the charger and see if that
works. If that 5-6V isn't sufficient, try a little more, but don't go
higher than 10-11V as this seems to be the operating voltage of the
battery and you don't want to over charge it.

It should reach those 5-6V relatively quickly.

This whole procedure perfect for NiCd, NiMH and similar batteries but
should also work for LiIon if you use the charger to finally charge it to
the full voltage.

Good luck!
Jocki
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