Oops, killed 3 Energizer 2500mAh AA's

benh

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I was going to recharge the batteries in my Belkin iPod battery pack, which takes 4 AAs.

On a whim, I decided to check each cell with a meter, and 1 cell read about 1.1 volts, and the other three read -0.01 volts!

Oops.
 

benh

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Seriously? It looks to me like they were sucked so dry they reversed polarity. That can't be good.
 

VidPro

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geesh how did you get 3 of 4 sucked dry :)
do you have a way to individually slap them up to a normal level, with a dumb charger? or by parelleling them with another battery, or a power supply? before you charge it TOGETHER in a series dumb charger?
cause that would be better in this situation.

the reason i mention getting them individually to a point where it will accept a charge , is if you dumb charge now in series one of them might not get going.

nuking them like that isnt good for them, but hey sometimes you gotta do what you gotta do, and if they last 30+ cycles they still were better than alkies, but as you know try not to do that.

they aint dead yet, they just got hurt.
 

bill_n_opus

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benh said:
I was going to recharge the batteries in my Belkin iPod battery pack, which takes 4 AAs.

On a whim, I decided to check each cell with a meter, and 1 cell read about 1.1 volts, and the other three read -0.01 volts!

Oops.

One time I forgot some cells in my wife's swiffer (takes 4xAA) and one of them registered really, really low in my BC-900. It would not charge and registered as "null" in the charger.

Eventually though, it finally registered after multiple attempts to insert - reinsert and began charging. Can't remember if the capacity is below normal or the battery is toast. Still works though.
 

tacoal

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bill_n_opus said:
One time I forgot some cells in my wife's swiffer (takes 4xAA) and one of them registered really, really low in my BC-900. It would not charge and registered as "null" in the charger.

Eventually though, it finally registered after multiple attempts to insert - reinserrt and began charging. Can't remember if the capacity is below normal or the battery is toast. Still works though.
Hi Bill,

The BC-900 will charge a low voltage battery (when it shows NULL) with very small current (about 0.06ma) to wake up the battery. So you don't need to insert-reinset procedure. Doing so will make the waking up time longer.

However, if the self discharge rate of a battery is to too high, this may not work. In this case, you need a dumb charger to do the job.
 

bill_n_opus

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tacoal said:
Hi Bill,

The BC-900 will charge a low voltage battery (when it shows NULL) with very small current (about 0.06ma) to wake up the battery. So you don't need to insert-reinset procedure. Doing so will make the waking up time longer.

However, if the self discharge rate of a battery is to too high, this may not work. In this case, you need a dumb charger to do the job.

Thanks. I didn't know that. Is that in the manual at all? Makes sense now that the engineers would think of such a thing.
 

tacoal

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bill_n_opus said:
Thanks. I didn't know that. Is that in the manual at all? Makes sense now that the engineers would think of such a thing.

This is not in manual. I found it by accident. I had a over discharged battery, which showed NULL when it was in BC-900. Then I connected a volometer to the battery to check the voltage when it was in the charger. I found that the voltage was constantly going up. After a while, the BC-900 started to change it normally. Later, I checked the circuit and found that a 47K resistor did this job.
 

MatajumotorS

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Some time ago i KILLED 14 (fourtheen) Mediatech 2400mAh AA cells at a time, i had made batterypack for my girlfrends bike light, and... once a pon a time ...

i heared at a night
au.gif
an explosion , then another then another !!! checked all places, everything - nothing. In the next morning ...:

1169478133.jpg


1169478139.jpg


1169478144.jpg


1169478150.jpg


I think, when i made this pack, cells was diferently charged, ad when discharged - some went to minus polarity, and then - big BOOM!! :grin2:
 

EngrPaul

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What was the battery pack cover made of? It should be thin and tight fitting, and all cells should be near the edge of the pack.

Charging creates heat. Heat must leave or the temperature will build up. If the temperature builds up, well... :poof:
 

MatajumotorS

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I had charged this pack several times before, everything was ok, pack was only warm i charged it at 1A.

The bag was made from leatherette, it saved me from fire and mess all around the room :laughing: everything stayed "in bag".
 

wptski

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MatajumotorS said:
I had charged this pack several times before, everything was ok, pack was only warm i charged it at 1A.

The bag was made from leatherette, it saved me from fire and mess all around the room :laughing: everything stayed "in bag".
A .1C charge for 16 hrs. on a discharged pack is said to balance the cells out.
 

nushipwright

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benh said:
I was going to recharge the batteries in my Belkin iPod battery pack, which takes 4 AAs.

On a whim, I decided to check each cell with a meter, and 1 cell read about 1.1 volts, and the other three read -0.01 volts!

Oops.

Hi Behn,

Can it be that you have the same factory faulty 2500mAh AA Energisers what I have?
Look at other forums, Energiser sold a LOT of faulty 2500mAh AA cells in the last year or so.
I happen to have 8 pieces out of which 5 self discharge at the speed of light! One week after a full charge and they're completely dead.

I just recharge them before every use, though it quite annoying.
 
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