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TommyC 10-23-2006 01:18 AM

Can NiMH batteries "just die" from non-use?
 
Four months ago, I got a new camera with a proprietary lithium battery
and have used that exclusively since.

Today, my wife and I both had something to go to, so I took the new
camera and my wife took the old one. Of course it didn't work when I
checked it yesterday, so of course I recharged the four NiMH batteries
that were in it.

When I put the batteries in the charger, two of the charger lights came
on, but two didn't (indicating that those batteries weren't charging).
I switched the batteries around, and the same batteries (now in
different compartments) again didn't make the lights come on.

I should have questioned that right there. Instead, I sent my wife off
with the camera (which turned on okay yesterday with the batteries in
it), and after about four shots, the camera died.

So my question is, can a battery (in this case, two batteries) just go
dead and not take a charge after only four months of no use or charging?
And if not, what other explanation could there be for the batteries to
not "light the lights" in the charger?

Paul Rubin 10-23-2006 01:27 AM

Re: Can NiMH batteries "just die" from non-use?
 
TommyC <m@nope.qrs> writes:
> So my question is, can a battery (in this case, two batteries) just go
> dead and not take a charge after only four months of no use or charging?


Sometimes "smart" chargers think the cell is shorted or they don't
even notice a totally discharged cell, so the cell doesn't get
charged. You could try a "dumb" charger to get some charge back into
the cell, maybe doing a slow overnight charge.

Dave Cohen 10-23-2006 01:41 AM

Re: Can NiMH batteries "just die" from non-use?
 
Paul Rubin wrote:
> TommyC <m@nope.qrs> writes:
>> So my question is, can a battery (in this case, two batteries) just go
>> dead and not take a charge after only four months of no use or charging?

>
> Sometimes "smart" chargers think the cell is shorted or they don't
> even notice a totally discharged cell, so the cell doesn't get
> charged. You could try a "dumb" charger to get some charge back into
> the cell, maybe doing a slow overnight charge.


I think Paul has the most likely answer. To directly answer your
question, after purchasing a set of the new Eneloop cells which do not
lose their charge when not used, I now have three sets of NiMH for which
I don't have much immediate use. So I did some web searching to see how
I should store them and it would appear they should do quite nicely
regardless of charge state. By the way, those Eneloops are doing very
well, bought them mid September, never charged them, 200 shots in my A95
and still running. I intend to post more on this after a few charging
cycles (which at the rate I use the camera may take a while), since
saying very much right now wouldn't be too meaningful.
Dave Cohen

Lefty 10-23-2006 02:19 AM

Re: Can NiMH batteries "just die" from non-use?
 

"TommyC" <m@nope.qrs> wrote in message
news:m-B50165.21155122102006@syrcnyrdrs-02-ge0.nyroc.rr.com...
> Four months ago, I got a new camera with a proprietary lithium battery
> and have used that exclusively since.
>
> Today, my wife and I both had something to go to, so I took the new
> camera and my wife took the old one. Of course it didn't work when I
> checked it yesterday, so of course I recharged the four NiMH batteries
> that were in it.
>
> When I put the batteries in the charger, two of the charger lights came
> on, but two didn't (indicating that those batteries weren't charging).
> I switched the batteries around, and the same batteries (now in
> different compartments) again didn't make the lights come on.
>
> I should have questioned that right there. Instead, I sent my wife off
> with the camera (which turned on okay yesterday with the batteries in
> it), and after about four shots, the camera died.
>
> So my question is, can a battery (in this case, two batteries) just go
> dead and not take a charge after only four months of no use or charging?
> And if not, what other explanation could there be for the batteries to
> not "light the lights" in the charger?


I would not give up on those cells just yet. I would be inclined to suspect
that the charger is the problem, not the batteries.

A charger that requires 2 cells for each indicator light has the 2 cells in
series. A better charger monitors the charge state of each individual cell.

Lets say be label each of the 4 cells, A, B, C, D. First charge A+B
together, and C+D together. Next mix things up. Charge A+C together and B+D
together. The last combination is of course A+D and B+C. You might find that
this will get you by, by that I mean, you will be able to get all 4 cells
charged, properly equalized.

Another way would be to skip what I just described and just get a decent
charger.

I buy cells in sets of 4, I keep the sets together, one way to do this is by
buying different brands. No way to mix them up.

Good luck, and please let us know how it turns out.

r.



Lionel 10-23-2006 03:04 AM

Re: Can NiMH batteries "just die" from non-use?
 
On Sun, 22 Oct 2006 22:19:27 -0400, "Lefty" <bitbucket@rudybenner.com>
opined:

>I buy cells in sets of 4, I keep the sets together, one way to do this is by
>buying different brands. No way to mix them up.


This is excellent advice. I don't buy different brands though, I just
label each set of cells differently (a strip of magic tape on each
cell, with a set number in marker pen), & store each set separately in
small plastic bags when they're in the camera bag. I currently own 4
sets of 4 NiMH 'AA' cells, & they're still working well after about 3
years & probably hundreds of charging cycles.
--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------


mark_digital© 10-23-2006 03:33 AM

Re: Can NiMH batteries "just die" from non-use?
 

"TommyC" <m@nope.qrs> wrote in message
news:m-B50165.21155122102006@syrcnyrdrs-02-ge0.nyroc.rr.com...
> Four months ago, I got a new camera with a proprietary lithium battery
> and have used that exclusively since.
>
> Today, my wife and I both had something to go to, so I took the new
> camera and my wife took the old one. Of course it didn't work when I
> checked it yesterday, so of course I recharged the four NiMH batteries
> that were in it.
>
> When I put the batteries in the charger, two of the charger lights came
> on, but two didn't (indicating that those batteries weren't charging).
> I switched the batteries around, and the same batteries (now in
> different compartments) again didn't make the lights come on.
>
> I should have questioned that right there. Instead, I sent my wife off
> with the camera (which turned on okay yesterday with the batteries in
> it), and after about four shots, the camera died.
>
> So my question is, can a battery (in this case, two batteries) just go
> dead and not take a charge after only four months of no use or charging?
> And if not, what other explanation could there be for the batteries to
> not "light the lights" in the charger?


I had the same problem the other day. I cooled them down and re-inserted
them into the charger.
mark_



ASAAR 10-23-2006 07:16 AM

Re: Can NiMH batteries "just die" from non-use?
 
On Mon, 23 Oct 2006 01:18:01 GMT, TommyC wrote:

> I should have questioned that right there. Instead, I sent my wife off
> with the camera (which turned on okay yesterday with the batteries in
> it), and after about four shots, the camera died.
>
> So my question is, can a battery (in this case, two batteries) just go
> dead and not take a charge after only four months of no use or charging?
> And if not, what other explanation could there be for the batteries to
> not "light the lights" in the charger?


Yes, it's possible to have cells ruined by leaving them in a
camera for an extended period, but whether that can happen depends
on the camera's design. If the batteries are charged and then put
in a box for four months, they'll lose charge, but won't be ruined.
If they're put in a camera that has an extremely low battery drain,
such as what a low power clock/calendar circuit would require, they
should also survive being left in the camera for many months. But
some cameras have unusually high current drains when powered off,
and they can and probably will ruin one or two cells if batteries
are left in the camera for several months. Consider a camera that
draws only 1 ma from the batteries when powered off. In one day it
would use 24 mAh. After 100 days (less than 4 months), 2,400 mAh
would be used, which is probably a lot more than even 2,700 mAh
batteries could provide since the batteries are also losing energy
during those months due to self discharge. When the first cell is
totally depleted, the remaining 3 batteries would continue powering
the "turned off" camera, (supplying over 3 volts), putting the first
cell that died into a reversed charge situation, eventually totally
killing it. When the second battery dies (approaches zero volts),
the remaining 2 cells would still be supplying over 2 volts to the
camera, and most digital cameras would probably completely power off
before this point, protecting the 3 remaining batteries, leaving
only one cell ruined. Some circuit designers (you know who you are,
Sony) design some of their digital devices that use 4 AA cells so
that they continue draining the batteries even after two of the 4
cells die. This would allow 2 of the 4 cells to be damaged very
quickly after those first two were depleted.

If your charger is designed to charge AA cells individually, then
it's likely that the two cells that wouldn't take a charge are now
bad. But if your charger is designed to charge AA cells in pairs,
rather than individually, it's possible that only 1 of your 4 NiMH
cells is damaged, and it's easy to find out if this is the case. If
each NiMH cell is marked to indicate cell A, B, C and D, and you've
discovered that when cells A and B are together they can't be
charged, just put cells in together differently so that cells A and
C are in one of the charger's bays and B and D are in the other bay.
If A and B are both bad, the charger should not be able to charge
any of them. But if only one cell was bad (assume it was cell A),
then you should see cells B and D charging, but this time cells A
and C wouldn't be charging. Of course it's much easier to see which
battery or batteries are defective with a better charger that's able
to charge and monitor each cell individually.

BTW, my first digital cameras (Canon Powershots) used proprietary
battery packs that were built using 5 AAA NiMH batteries. When
powered off, they consumed battery power at a rate well in excess of
1ma. The manual warned that if the camera wouldn't be used soon
(like for only several days) that the battery pack should be
removed. I never formally tested it, but I think that the battery
pack would not be able to turn the camera on if it was left in the
camera for as long as a week or two, of if it could turn it on,
would only be able to take a couple of shots before dying.

If you have one bad cell you may be able to "revive" it by
charging it for a while in a "dumb" charger. But the harsh
treatment may have caused it to lose much of its original capacity.
If it has lost 50% of its capacity, then even if the other 3 cells
are as good as new, the one bad cell would cause the entire battery
pack to appear to have lost 50% of its capacity, and in this case it
would be wise to replace the damaged cell with a new one. Maybe
even wiser to replace all four. And of course in the future, if
your camera is a battery drainer when powered off, don't leave
batteries in it, unused, for months at a time. :)


Dimitris M 10-23-2006 08:35 AM

Re: Can NiMH batteries "just die" from non-use?
 
Paul has give the right advice. All the other advices are wrong. I will try
to explain with my poor english what happened with the MiMH. (BTW, I am
electrononics engineer)

1. The NiMH has an enormous rate of self discharge, about 40 to 60% per
month. In case of storage, it MUST be charged at least every two months.

2. In case that the batteries are stored even for a month uncharged or
stored for more than 3 months charged, the charge can become very low. In
that case, as Paul says, the (not so) "smart" chargers think that the
battery is dead. The solution is just to charge it for some minutes (not
necessarily overnight) in a really dumb charger, just to give a basic charge
to make the battery voltage became more than a certain level, about 1 V.
After that, the battery can be charged normally in the "smart" charger.

3. SOS: You can NOT mix batteries of different brand or capacity. If one
battery in a 4 battery (series) array will became discharged when the others
still work and supply current, this discharged battery will be destroyed
very fast.

4. ALL the MiMH chargers charge the batteries independently, not in series.
I insist: ALL. If one charges the batteries in series, then the designer and
the builder of that charger must be "executed" as criminals ;-)
--
Dimitris M


>> So my question is, can a battery (in this case, two batteries) just go
>> dead and not take a charge after only four months of no use or charging?

>
> Sometimes "smart" chargers think the cell is shorted or they don't
> even notice a totally discharged cell, so the cell doesn't get
> charged. You could try a "dumb" charger to get some charge back into
> the cell, maybe doing a slow overnight charge.




Jan 10-23-2006 08:57 AM

Re: Can NiMH batteries "just die" from non-use?
 

> When I put the batteries in the charger, two of the charger lights came
> on, but two didn't (indicating that those batteries weren't charging).
> I switched the batteries around, and the same batteries (now in
> different compartments) again didn't make the lights come on.
>


I've seen the same (gp powerbank charger).
Unplugging the charger from the mains and plugging in again helps (sometimes
after 2 or 3 times).

The strange thing : Last time I've put in 4 batteries (2x 2 in series, 2
type of brands). Both didn't turn on
the charging led. Once they started, both started.

The cells were 6 months old.

Jan



Ron Hunter 10-23-2006 10:54 AM

Re: Can NiMH batteries "just die" from non-use?
 
TommyC wrote:
> Four months ago, I got a new camera with a proprietary lithium battery
> and have used that exclusively since.
>
> Today, my wife and I both had something to go to, so I took the new
> camera and my wife took the old one. Of course it didn't work when I
> checked it yesterday, so of course I recharged the four NiMH batteries
> that were in it.
>
> When I put the batteries in the charger, two of the charger lights came
> on, but two didn't (indicating that those batteries weren't charging).
> I switched the batteries around, and the same batteries (now in
> different compartments) again didn't make the lights come on.
>
> I should have questioned that right there. Instead, I sent my wife off
> with the camera (which turned on okay yesterday with the batteries in
> it), and after about four shots, the camera died.
>
> So my question is, can a battery (in this case, two batteries) just go
> dead and not take a charge after only four months of no use or charging?
> And if not, what other explanation could there be for the batteries to
> not "light the lights" in the charger?


Yes. You didn't say how these batteries were stored during the time of
non-use. If they were in the camera, and the camera was drawing power,
say to keep an internal clock alive, they could have discharged to the
point of polarity reversal, which can permanently damage an NIMH battery.
NIMH batteries suffer from self-discharge, which means they lose their
charge rather rapidly (compared to other chemistries) when just sitting
around. This is no problem to those who use their cameras often and
recharge the NIMH batteries often. For those who use their cameras
infrequently, another type of battery chemistry is recommended.


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