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Nimh battery not as full as alkaline's?

 
 
JakeC
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      02-11-2007
Hi all,

I just bought a two sets of 4 Energizer 2500mAh batteries yesterday. One
set came with a charger. I used that charger to charge both of the sets.
It took nine hours to finish charging each set (as indicated by the
turning off of the LED light on the charger and the warmth of the
batteries). Then I used a small, handy battery tester to see how "full"
the batteries are. Sadly my tester says they're just above "replace". I
remembered I also tested one of the sets right off the package and I got
the same indication. It seems like the charging has no effect on the
batteries. I also put a pair of the batteries into a flash light. It
turned out that the light was dimmer than that came out with the pair of
the no-name alkaline batteries originally sitting in that flash light.

Is there something wrong with the charger? Shouldn't my tester have its
pointer moving all the way across the "good" area of the tester, just
like any new batteries will make it to and show that the batteries are
full? Do I need to re-charge the batteries?


Thanks in advance for your input.



JC
 
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Pete D
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      02-11-2007
You cannot use the same tester for alkaline and NiMh, alkaline have a
nominal voltage of 1.5 volts, NiMh have a nominal voltage of 1.2 volts.

"JakeC" <(E-Mail Removed)> wrote in message
news:59Kzh.943347$R63.145309@pd7urf1no...
> Hi all,
>
> I just bought a two sets of 4 Energizer 2500mAh batteries yesterday. One
> set came with a charger. I used that charger to charge both of the sets.
> It took nine hours to finish charging each set (as indicated by the
> turning off of the LED light on the charger and the warmth of the
> batteries). Then I used a small, handy battery tester to see how "full"
> the batteries are. Sadly my tester says they're just above "replace". I
> remembered I also tested one of the sets right off the package and I got
> the same indication. It seems like the charging has no effect on the
> batteries. I also put a pair of the batteries into a flash light. It
> turned out that the light was dimmer than that came out with the pair of
> the no-name alkaline batteries originally sitting in that flash light.
>
> Is there something wrong with the charger? Shouldn't my tester have its
> pointer moving all the way across the "good" area of the tester, just like
> any new batteries will make it to and show that the batteries are full? Do
> I need to re-charge the batteries?
>
>
> Thanks in advance for your input.
>
>
>
> JC



 
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Cgiorgio
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      02-11-2007

"JakeC" <(E-Mail Removed)> schrieb im Newsbeitrag
news:59Kzh.943347$R63.145309@pd7urf1no...
> Hi all,
>
> Is there something wrong with the charger? Shouldn't my tester have its
> pointer moving all the way across the "good" area of the tester, just like
> any new batteries will make it to and show that the batteries are full? Do
> I need to re-charge the batteries?
>
>
> Thanks in advance for your input.
>
>
>
> JC


Nope.
Alkaline cells have a nominal output voltage of 1.5 Volts, without a load a
new alkaline has nearly 1.6 Volts between its terminals. A NiMH cell has a
nominal voltage of 1.2 Volts, when fully charged they will have around 1.35
Volts with no load connected.

In high current applications (like in a digital camera) the output voltage
of Alkalines drops much faster than that of NiMH's, because they have higher
internal resistance (Ohm's law). Most cheap testers do not simulate a high
current load (that would also unnecessarily shorten the life of primary
cells).

It is a good idea to use your new rechargeable batteries until your camera
shows a low battery warning and to recharge them only then. Many NiMH cells
reach full capacity only after a few full charge / discharge cycles. After
that it is sufficient to do a full discharge / charge cycle about every 3 -
6 months.


 
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Just D
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      02-11-2007
"Cgiorgio"
> It is a good idea to use your new rechargeable batteries until your camera
> shows a low battery warning and to recharge them only then. Many NiMH
> cells reach full capacity only after a few full charge / discharge cycles.
> After that it is sufficient to do a full discharge / charge cycle about
> every 3 - 6 months.


We discussed that here a month or two ago and found that the full discharge
will kill the battery forever. So that's a very good advice that you just
gave! Roll back to the history and try to find the previous thread before
you give such an advice one more time.

Just D.


 
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Cgiorgio
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      02-11-2007

"Just D" <(E-Mail Removed)> schrieb im Newsbeitrag
news:UsKzh.6048$(E-Mail Removed)...
> We discussed that here a month or two ago and found that the full
> discharge will kill the battery forever. So that's a very good advice that
> you just gave! Roll back to the history and try to find the previous
> thread before you give such an advice one more time.
>
> Just D.
>

Please learn to read before criticizing posts. Discharging until a battery
warning appears and deep discharging are completely different meanings.
Usually a battery warning will appear around 1.05 Volts cell voltage which
is far from zero Volts (around 1050 milliVolts to be precise). If you want
to learn a bit about different battery types, you could read the material at
www.batteryuniversity.com . While latest developments are not taken into
account in that information, the basic information there is still valid.


 
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ASAAR
Guest
Posts: n/a
 
      02-11-2007
On Sun, 11 Feb 2007 19:30:09 GMT, JakeC wrote:

> I just bought a two sets of 4 Energizer 2500mAh batteries yesterday. One
> set came with a charger. I used that charger to charge both of the sets.
> It took nine hours to finish charging each set (as indicated by the
> turning off of the LED light on the charger and the warmth of the
> batteries). Then I used a small, handy battery tester to see how "full"
> the batteries are. Sadly my tester says they're just above "replace". I
> remembered I also tested one of the sets right off the package and I got
> the same indication. It seems like the charging has no effect on the
> batteries. I also put a pair of the batteries into a flash light. It
> turned out that the light was dimmer than that came out with the pair of
> the no-name alkaline batteries originally sitting in that flash light.
>
> Is there something wrong with the charger? Shouldn't my tester have its
> pointer moving all the way across the "good" area of the tester, just
> like any new batteries will make it to and show that the batteries are
> full? Do I need to re-charge the batteries?


There's probably nothing wrong with the batteries. Fresh alkaline
batteries start out at a voltage just above 1.5v and just charged
NiMH (and NiCD) batteries measure slightly above 1.2 volts. So
your tester and flashlight are both showing you the expected
results. But as both battery types are used, the voltages will
drop, and if you have two flashlights running simultaneously, one
powered by alkalines and the other by your NiMH cells, before too
long the alkaline powered flashlight will become much dimmer than
the one powered by the NiMH cells. When used in devices that use
very, very small amounts of energy, both battery types will last
about the same amount of time. Cameras, on the other hand require
moderate to large amounts of power, and for these battery hungry
devices, alkaline AA cells are completely outperformed by high
capacity NiMH cells, usually lasting twice as long in some recent
cameras, and the difference can be much greater in older cameras.

I have a battery tester app. that runs on my Palm PDA, and it's
configurable, allowing several different battery types to be
selected. Same goes for some electronic devices (usually radios)
that have a switch to allow you to set it to "alkaline" or
"rechargeable". This allows them to show a more accurate battery
status than your voltage tester, which apparently is designed only
for alkaline batteries. Some testers are cruder than others. For
example, I have a small, inexpensive tester that uses the same
resistive load for all battery sizes, AAA, AA, C and D. Because the
smaller batteries have higher internal resistances, fresh, smaller
batteries won't move the needle as high as fresh, larger batteries,
even though they should appear the same. Better testers have ways
to present different resistive loads to different size batteries,
making them a little bit more accurate. The bottom line is that
your battery tester can provide misleading results unless you know
more about how batteries really perform. If you're interested,
there are some pretty good charts on the battery data sheets that
can be downloaded from Energizer's website. They're PDF files.

 
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Just D
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      02-11-2007
"Cgiorgio"
> Please learn to read before criticizing posts. Discharging until a battery
> warning appears and deep discharging are completely different meanings.
> Usually a battery warning will appear around 1.05 Volts cell voltage which
> is far from zero Volts (around 1050 milliVolts to be precise). If you want
> to learn a bit about different battery types, you could read the material
> at www.batteryuniversity.com . While latest developments are not taken
> into account in that information, the basic information there is still
> valid.


Sorry if I probably wasn't correct or polite writing my previous message.
Just look what you wrote: "Many NiMH cells reach full capacity only after a
few full charge / discharge cycles. After that it is sufficient to do a full
discharge / charge cycle about every 3 - 6 months." It would definitely
mislead me if I just read about complete full discharge after 3-6 months and
I'd follow this advice for sure using whatever is available, standard
discharger inside the charger, the device where this battery works, etc. For
example very good advice I got from the Micron laptop manual. It recommended
to completely discharge the battery at least one time every half-a-year. To
do that COMPLETELY I need to open the BIOS settings and leave the laptop
working with this battery until it shuts down, actually dies. Very good
advice completely killed the battery much sooner that it could happen. I
assume that some of the smart rechargers are able to understand where is the
killing level of the battery but we need to be careful giving these advices,
not all batteries will survive after complete discharge.

Just D.



 
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MG
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Posts: n/a
 
      02-11-2007
> I just bought a two sets of 4 Energizer 2500mAh batteries yesterday.

I bought a set of Energizer 2500 batteries a while ago. They are the worst
batteries I have. Their discharge rate when not in use is very high. I
prefer the ageing 1700mAh batteries that came with my camera to the
Energizers. I won't be buying Energizers again.

MG


 
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Joseph Meehan
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      02-11-2007
JakeC wrote:
> Hi all,
>
> I just bought a two sets of 4 Energizer 2500mAh batteries yesterday.
> One set came with a charger. I used that charger to charge both of
> the sets. It took nine hours to finish charging each set (as
> indicated by the turning off of the LED light on the charger and the
> warmth of the batteries). Then I used a small, handy battery tester
> to see how "full" the batteries are. Sadly my tester says they're
> just above "replace". I remembered I also tested one of the sets
> right off the package and I got the same indication. It seems like
> the charging has no effect on the batteries. I also put a pair of the
> batteries into a flash light. It turned out that the light was dimmer
> than that came out with the pair of the no-name alkaline batteries
> originally sitting in that flash light.
> Is there something wrong with the charger? Shouldn't my tester have
> its pointer moving all the way across the "good" area of the tester,
> just like any new batteries will make it to and show that the
> batteries are full? Do I need to re-charge the batteries?
>
>
> Thanks in advance for your input.
>
>
>
> JC


As you know from the other post, there is nothing wrong. However I have
a suggestion. The battery charger is a very important part of the life of
those batteries. You wrote: "turning off of the LED light on the charger "
In general those chargers with as single LED charge indicator is charging
all the cells the same way. Since cells are never exactly the same some
really need a little more and some a little less. Those chargers that
tailor their charge for each cell (generally have a light for each cell)
will usually give better results.

--
Joseph Meehan

Dia 's Muire duit



 
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ASAAR
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Posts: n/a
 
      02-11-2007
On Sun, 11 Feb 2007 13:15:40 -0700, Just D wrote:

> I assume that some of the smart rechargers are able to understand where is
> the killing level of the battery but we need to be careful giving these advices,
> not all batteries will survive after complete discharge.


As far as I can tell, all of the battery chargers that have
discharge circuits only discharge until individual cells have
dropped to about 1.0 volts. At that point, unlike alkalines which
will still have nearly half of the energy of fresh alkalines
remaining, rechargeables will be about 100% depleted, so it's
unnecessary (and unwise) to discharge them any further. My Fuji is
apparently one of the few camera that has a menu item that allows
the camera to discharge NiMH batteries. Of course the manual says
that it shouldn't be used for alkaline batteries, but I'm sure that
at least a few naive Fuji owners must have tried that. <g>

 
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