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Subject: Re: Battery usage indications?
From: Andreas Zwirtes (zwirtes_at_gmx.de)
Date: 2002-10-18


Since my first set of batteries is slowly giving up after a year of
intense usage, I tried
the second one. The Archos didn't even spin up the hd with this set,
even it was
fully charged.

That was due to the inner resistance of one defective cell. While
trying to spin up, the
over all supply voltage dropped below 4V (scope-metered). I've measured the
capacity of the batteries and they all had abot 1420-1430mAh. Only one
of them
dropped slightly below, it had only 1350mAh. I thought that this
wouldn't make
much of a difference, but it did. In the beginning, they were all very
bad, but
three of them recovered after cycling them 10-15 times in a battery
analyzer.
The one with 1350 is dead and useless, even thogh it has (now) nearly
full capacity.

TO EVERYBODY: If you've got your second set still in the blister package,
unpack it and use it minimum every 2-3 month (complete discharge/charge).
So you keep it fresh and usefull. The one battery in my set very likely died
from self-discharge.

NOTE: You shouldn't replace one single battery in a set, if it is defective.
That is for a good reason: In a normal fresh set of batteries, all batteries
have very similar capacity and discharge behaviour. Once the batteries
are empty, that causes the all-over battery voltage to go down very fast,
because all of them are empty at once. If you replace only one, it will hold
its voltage much longer than the others and also the voltage of the maybe
8/10 empty battery is much higher than the voltage of the empty ones. So
the overall voltage of the pack is significantly higher than it should
be. This
makes the device think it has almost 3/4 empty batteries and calculate a
wrong remaining time. Also the three other batteries are heavily drained
before shutdown and it is very likely that they fail after a few cycles.
This
is a common "n-batteries in a row" problem.

QUESTION:
I'd want to ask you all a big favour: If you've got a defective set (it
should be a
complete set of drained original or replacement batteries), I'd be very
happy
if you could send it to me. I'd pay the postal service, if you're not
sure about
(should be in Europe, otherwise it would be too expensive). If you send
batteries , they should be in optically ok condition.

What this is for:
I want to do some tests with single batteries and battery sets regarding
their
charge/discharge behaviour under varying conditions. Also I'd like to do
some
tests on overcharging with different currents and total drainage. That would
be very expensive, if I bought new batteries for this, as you might
guess :)

It hope, that this text has at least been usefull for some people who wonder
about the miracles of battery cycles. If you want to help me, just drop me
a message.

Thank you very much in advance,

Andreas Zwirtes

Bradley Alexander schrieb:

>On Wed, 2002-10-16 at 15:28, Josh (Norm) Audette wrote:
>
>
>><NORM>
>> How old are your batteries? Also, do you use a charger when you're in
>>
>>
>
>The batteries came with the unit, >1 yr old. I bought it secondhand from
>a coworker, and she said that she had never used the second set of
>batteries (which are in there now). I used to use a car charger, but do
>not at present. (it was a cheap charger, and died on me.)
>
>
>
>> the car? Rechargeable batteries alter their charge/discharge cycle
>> when you don't charge and discharge them fully. If you get into your
>> car and plug in the charger whenever you drive, you'll start to alter
>> your batteries' discharge characteristics. You can fix this by fully
>> discharging and then charging it a few times. Also, have you tried
>> running it on another set of batteries?
>>
>>
>
>This is the second (unused) set of batteries.
>
>
>
>



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