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Old Dec 3, 2005, 4:32 PM   #1
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Hi everyone, I am using the Energizer 2500mAh aa batteries. Some of the batteries after 1 week of sitting on the shelf after they have been fully charged they discharge down to 1.28Volts others after the same 1 week will measure 1.36volts. Would there be any concern for the ones that are at a lower voltage after 1 week? I use the batteries in a 4 inch tv and the lower voltage ones last almost as long as the higher voltage ones. Can it be possible that the mAh are the same in all the batteries but the voltage can be different? I do know that when you use nihm batteries in a device the voltage drops down to 1.20 for the whole time that they have enough energy. Thank you for your help.

Dan
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Old Dec 3, 2005, 6:08 PM   #2
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Hello Dan,

1.36 volts is about where they should be. Sometimes it takes 5-10 cycles to "break" the cells in.

I would suggest that you keep using them for a few more cycles, then check them again. If you still see the dropping down in voltage, contact Energizer.

Tom
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Old Dec 4, 2005, 1:01 AM   #3
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they lose 1/2 to 1% per day if you are taking shots on a small point and shoot with a flash after 2 weeks you should have no problem with 30 pic even if you dont top off batterys on the 2500 mah but !!!!! down the line your internal resistance will cause problems, there are some batterys you can buy that has so much internal risistance they just dont work worth a s---!!!!
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Old Dec 4, 2005, 1:49 AM   #4
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all they all NiMH batteries, or are some of them NiCad? different chemistries produce slightly different voltages. normal range for rechargeables is 1.2 to 1.35 or so, depending on type. mostrechargeable batteries max out at the 1.2-1.35v range, but maintain about 1.2v for most of their charge life, then tend to die abruptly at theend (as opposed to alkalines, which start at about 1.5v,but taper offsteadily - with noticeably weakening performance -until they're usedup).typically, rechargeable AA cells lose about 15-20% of their initial charge after sitting for a month, so it's best to use them as soon after recharging as possible.

voltage and mAh are two different, but interrelated, things. voltage is a measure of the electrical power a battery can deliver, while mAH (milli-Amp hours) is a measure of how long the battery willmaintain usable voltageata givenoutput current. a 2500mAh battery should provide approximately twice the life of a 1200mAh cell in the same application, even though their output voltages are the same.
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Old Dec 4, 2005, 2:45 AM   #5
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i agree with your statement but alk battery have a higher internal resistance so on dig camera they are not the best iimo but nimh 2500 mah energizer have less resistance so you get you needed power right away when useing a dig camera

this is a major issue with dig camera . been there done that
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Old Dec 4, 2005, 9:35 AM   #6
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dekelsey61 wrote:
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Some of the batteries after 1 week of sitting on the shelf after they have been fully charged they discharge down to 1.28Volts others after the same 1 week will measure 1.36volts.
That tells that some batteries are little better/worse than others.
You can use voltage to find out if you have one bad cell among others. Normally voltage should be around 1.35-1.4 after charging, especially if one cell shows only 1.2V it's either bad or halp empty.
So for this to work you have to use intelligent charger with separate charging/control circuit for every cell. But that's always vice in general.

Worst kind charger is something which has timer.
If manual/ads talk about timer don't buy that because it always charges batteries with constant current and constant time without caring is it frying full batteries or are they left halp empty.
Then little better chargers monitor voltage and charging current, but also these can leave other cells half empty if one of them was originally more full than others.



squirl033 wrote:
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voltage and mAh are two different, but interrelated, things. voltage is a measure of the electrical power a battery can deliver, while mAH (milli-Amp hours) is a measure of how long the battery willÂ*maintain usable voltage...
Quite wrong.
Weren't these taught in school's physics classes?

http://www.4qdtec.com/water.html
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Old Dec 4, 2005, 1:15 PM   #7
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E.T wrote:
Quote:
squirl033 wrote:
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voltage and mAh are two different, but interrelated, things. voltage is a measure of the electrical power a battery can deliver, while mAH (milli-Amp hours) is a measure of how long the battery willmaintain usable voltage...
Quite wrong.
Weren't these taught in school's physics classes?

http://www.4qdtec.com/water.html
yeah, i've seen that analogy before, many times. i just don't use plumbing terminology when discussing electronics, unless i'm talking to someone who doesn't know a capacitor from a screen door. i do believe, E.T, that after spending half my adult life in the electronics industry, with 9 years of that making my living as a technician, that i understand what voltage and battery capacity are...


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Old Dec 4, 2005, 3:46 PM   #8
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Now I understand why pretty much every company producing electronic devices has factories in Asia...
I don't know what names they use in US but voltage definitely isn't measure of how much power battery can deliver. Measure for total energy/power is watt hour.
(which can be coverted to Joules)


http://www.solarexpert.com/GlossaryPV.html
http://www.mos.org/sln/toe/glossary.html


Here's some comparison of different batteries, although it doesn't include newest higher capacity models.
http://www.imaging-resource.com/ACCS/BATTS/BATTS.HTM
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Old Dec 4, 2005, 5:16 PM   #9
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"power" is a productof voltagex current (Ohm's law), but to most people not familiar with electrical terminology, "voltage" is a measure of power a battery can produce, as opposed to "amps", which is current, and is dependent on the device being powered, not on the battery. amps and volts together produce "watts", which is a measure of power. 1 amp x 1 volt = 1 watt.a "watt-hour" is simply a measurement of how much power apower sourcecan deliver over time - how many watts a given power source can provide for a period of one hour.given the same current draw, a12v battery will provide 8 times the power (watts)of a 1.5v battery. in that regard, voltage is a crude measure of the power a battery can produce.

milliamp hours is a measure of how long the battery will provide usable power at rated current draw. 1000 mAh is equal to a 1 amp-hour (AH) rating, and a battery rated at 1000mAh can provideusable voltage at a current of 1 amp for a period of 1 hour. For example, a 2000 mAhbattery rated at 1.5v will sustain a 2000 milliamp (2 amp) draw (producing 3 watts of power) for one hour before dropping to a voltage level that is considered discharged. if the current draw is constant, at say 1 amp, a 1700mAh battery will provide 1.7 hours of service before its output voltage falls below the level required to operate the device. a 2000mAh battery will last 2 hours.the mAh rating of a battery is therefor a relativeindicator of its capacity in terms of how long it will last in any given device.


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Old Dec 5, 2005, 11:29 AM   #10
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squirl033 wrote:
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...but to most people not familiar with electrical terminology, "voltage" is a measure of power a battery can produce
Why to prolong such illusions?

Let's take example, many digicams use AA sized batteries, now ordinary disposable alkalines have 1.5V as rated voltage and with NiMHs it's 1.2V.
But surprise, surprise, if you put alkalines to digicam they give much fewer shots, in power hungry digicams you'll barely get ten - twenty shots.

Or how about comparing 9V battery (IEC 6LR61) to 1.5V D battery. (IEC LR20)
Common capacity of 9V batteries appears to be around 600 mAh. Now D-cells have capacities over 20 000 mAh.
Also if you increase discharge current to say, 100 mA, 9V batteries literally collapse, they just can't output electric power at bigger rates.



Ampere (A) is a measure of electric current, it tells at what rate electric charge is moved.
That leads to measure of electric charge, Ampere second (As) which is current multiplied by time, in one second one ampere current transfers 1 As electric charge. Hour contains 3600 seconds so 1 Ah is naturally equal to 3600 As. (as side note actual "official" unit of electric charge is Coulomb which is equal to 1 As)

Now those are just measures for electric charge and rate at which it's moved so we need other units.

And that's job of watt (W) which measures consumption rate of electric power. Its formula is voltage times current, which means 1 watt is equal to 1 volt ampere. It tells at what rate device consumes (or produces) electric power.
For a total energy consumed we need to know also time, its formula is power consumption rate multiplied by time which leads to watt second and watt hour. And because one hour contains 3600 seconds 1 Wh is equal to 3600 Ws.
But with ordinary electric devices using watt seconds would lead to hard to remember long numbers so Wh is used commonly. (prefix k means kilo, 1000, so 1 kWh is just 1000 Wh, nothing stranger than that)
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