1.5V "button cell" battery changes polarity???

[Terry]

More electrics than electronics, perhaps, but what might cause a 1.5
button cell battery (such as used in watches, calculators, car keys
with remote capabilities etc ) to change polarity after a month or
two? Only one of four batteries (in a car key in this instance) seems
to be affected.

 

[Ron(UK)]

More electrics than electronics, perhaps, but what might cause a 1.5
button cell battery (such as used in watches, calculators, car keys
with remote capabilities etc ) to change polarity after a month or
two? Only one of four batteries (in a car key in this instance) seems
to be affected.

The cell failed then was reverse charged by the other cells in the battery

RonUK

 

[Terry]

The cell failed then was reverse charged by the other cells in the battery

OK, could this in any way be the fault of the key itself, or is it
more likely to be a cheap battery?

 

[Ron(UK)]

OK, could this in any way be the fault of the key itself, or is it
more likely to be a cheap battery?

If all the cells are just in series, then cheap battery

Ron

 

[Baron]

OK, could this in any way be the fault of the key itself, or is it
more likely to be a cheap battery?

Its a natural phenomena ! You are never going to get four batteries to
have identical voltages and deliver identical currents ! So at some
point, one of the batteries is going to become depleted first. Then
the current through it causes it to become charged in reverse.

This also applies to rechargeable batteries as well. Its a particular
problem with the sort of battery packs used in things like electric
drills ! Never let them become completely discharged for this reason !

This is why you will see manufacturers warnings to replace all the
batteries at once with new ones.

I have a remote control that uses four AA cells and at some point it
stops working. I then test the cells that I take out, throw the bad
one away and use the other three in things like my wall clock or other
remote that uses only two batteries.

 

[Terry]

Its a natural phenomena ! You are never going to get four batteries to
have identical voltages and deliver identical currents ! So at some
point, one of the batteries is going to become depleted first. Then
the current through it causes it to become charged in reverse.

This also applies to rechargeable batteries as well. Its a particular
problem with the sort of battery packs used in things like electric
drills ! Never let them become completely discharged for this reason !

This is why you will see manufacturers warnings to replace all the
batteries at once with new ones.

I have a remote control that uses four AA cells and at some point it
stops working. I then test the cells that I take out, throw the bad
one away and use the other three in things like my wall clock or other
remote that uses only two batteries.

Thank you both. I'm glad that it's not the key that's doing it!

 

[William Sommerwerck]

This happened to me a few years ago with the N cells in an HP calculator.

 

[Terry]

This happened to me a few years ago with the N cells in an HP calculator.

The odd thing (to me, at least) is that although such button cells
can't be charged once they're dead, they can apparently be reverse
charged.

 

[Allodoxaphobia]

The odd thing (to me, at least) is that although such button cells
can't be charged once they're dead, they can apparently be reverse
charged.

Having a "charge" and having a "polarity" are pretty much two separate
things.

 

[Don Bowey]

Having a "charge" and having a "polarity" are pretty much two separate
things.

So what do YOU call it when a cell's voltage polarity becomes reversed?

 

[[email protected]]

Reversed Polarity.
cuhulin

 

[Franc Zabkar]

Having a "charge" and having a "polarity" are pretty much two separate
things.

I'd connect a resistor across the battery and monitor the voltage as
it "discharges". A quick test and measure with a 100K resistor and
then a 10K and 1K should give you a feel for how much stored charge
there is.

- Franc Zabkar

 

[z]

The odd thing (to me, at least) is that although such button cells
can't be charged once they're dead, they can apparently be reverse
charged.

well, you can often recharge them in the positive direction, but
they're not designed for it, so bad things might happen, like they
build up internal pressure and leak. chemically, though, all these
electrochemical reactions are reversible unless one of the products is
a gas or something and goes away.

 

[bz]

well, you can often recharge them in the positive direction, but
they're not designed for it, so bad things might happen, like they
build up internal pressure and leak. chemically, though, all these
electrochemical reactions are reversible unless one of the products is
a gas or something and goes away.

Not just leak. Explode. Spread toxic chemicals.

This can happen if they are reverse charged, overcharged or charged too
rapidly. I stuck one into a 'universal battery charger' and forgot about
it until I hear a loud bang a few minutes later! Made one heck of a mess.

Attempting to charge a mercury cell has additional hazards because heated
mercury out-gasses enough mercury vapor to be fatal.








--
bz 73 de N5BZ k

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.

[email protected] remove ch100-5 to avoid spam trap

 

[z]

Not just leak. Explode. Spread toxic chemicals.

an explosion is just a real fast leak.

 

[z]

   With shrapnel.

--
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Add this line to your news proxy nfilter.dat file
* drop Path:*aioe.org!not-for-mail to drop all aioe.org traffic.

http://improve-usenet.org/index.html

conversely, a leak is just any explosion where you can run away from
it.

 

[bz]

conversely, a leak is just any explosion where you can run away from
it.

You could say that a leak is a sssslllloooooowwwww explosion.

Slow as molasses in January.

But that reminds me....

Have you heard of the 'Great Molasses Disaster'?

http://en.wikipedia.org/wiki/Boston_Molasses_Disaster





--
bz 73 de N5BZ k

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.

[email protected] remove ch100-5 to avoid spam trap

 

[z]

Have you heard of the 'Great Molasses Disaster'?

http://en.wikipedia.org/wiki/Boston_Molasses_Disaster

heard of it? I've actually smelled it. (did not dealt it, however)

 

[z]

   Try that with a high pressure steam leak and get back to me, if they
find all the pieces.

like back in sixth grade, where i discovered that if you unscrewed the
valve on the big steam line running through the schoolroom closet far
enough, it would actually come out of the pipe. hilarity ensues.