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Old Sep 6, 2012, 11:30 AM   #1
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Default Testing Batteries Something Other Than Volts?

Hi,

I am new to the forum and have read many posts but couldn't find anything that addresses this issue.

We have more than one digital camera that shows the batteries are weak so we replace them and everything works fine. However, I have taken the removed batteries and tested them and they show 1.499 volts. The batteries are Kodak Digital Camera batteries AA ZR6. In this case, all 4 of the batteries tested the same voltage but yet the camera wouldn't function until they were replaced.

This also happened on Energizer Alkaline Batteries they tested at 1.45 volts and this was a different camera. Same thing the camera indicated they batteries had to be replaced.

I have checked for anything that might be in the way of the contacts of the camera and the battery and there isn't anything that I can see.

So is there some other measurement I should be considering rather than volts? Or, is there another explanation?

I am asking so that I will know if I these batteries are used up. Short of putting them in other electronic devices I want to be able to determine their viability using a digital meter, if possible.

Thanks,

Randal
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Old Sep 6, 2012, 4:40 PM   #2
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G'day Randal

Firstly - welcome to Steve's ... there's plenty of good advice floating around here...

As to batteries and voltage vs amperage, that's a slightly different story
Like you, I see batteries rated 'simply' via their voltages, when amperage / storage capacity is what's more important

To answer your Q ... last week I bought a new digital miltimeter and it had 3 terminals rather than the traditional 2 terminals - the 3rd terminal was connected to an amperage gauge for power less than 10 Amps

I have no reason to try it ~ but shall do so & give you another answer to this Q

Hope this helps - there's also a good chance that another here will have a better one too
Regards, Phil
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Old Sep 7, 2012, 7:57 AM   #3
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Thanks for getting back to me. Yes, that is the dilemma I am thinking that measuring current will indicate whether the batteries should be recycled or not, even though the voltage is normal.

This leads me to the question, how do you test for current on a AA battery? I have a digital meter that has amperes but when I test them nothing shows on these batteries or even brand new batteries.
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Old Sep 10, 2012, 11:57 PM   #4
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You should be using a dedicated battery tester, which tests voltage under load. These are usually available at places such as Radio Shack.
No-load voltage will generally tell you the state of charge, but doesn't tell much about the condition of the cell. To try to put it simply, a cell has internal resistance, and under load, there is an internal voltage drop. If this resistance is too high, the cell will not have sufficient voltage when under a load, and your camera will detect it as low. The internal resistance of rechargeable cells is considerably lower than alkaline cells, and cameras are mostly made to run on the rechargeables. Often, alkaline cells, even those marketed as "digital", will have a pretty short life in a camera, even though a tester will show them as still good.

brian
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Old Sep 13, 2012, 10:37 AM   #5
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That is the best explanation I have seen, Thanks a lot.

I have a battery tester from RS and it was the alkaline batteries that were used up too quickly. knowing the rechargeable batteries are the best choice means we will change what we have been using.

How do the lithium batteries compare with the internal resistance? Also, is there some way to measure the internal resistance a battery has. Would that just be using a DMM and put it on ohms to test for the resistance?

Thanks,

Randal
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Old Sep 13, 2012, 4:00 PM   #6
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Lithium AA cells that I have used have a higher initial voltage (slightly) than alkaline cells, and the internal resistance appears to be lower, but higher than the NiMH rechargeables. I have used the lithiums in my Minolta D7hi, which is tough on batteries, and the lithium cells got fairly hot, though they did continue to operate where alkaline cells would have quit.

In order to test internal resistance, you need a setup to measure the cell voltage under a variety of loads, and then calculate the value. It can't be measured directly, and it will change with the state of charge of the cell. Using an Ohmmeter directly on a voltage source could possibly damage the meter.

brian
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Old Sep 14, 2012, 12:13 PM   #7
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OK, that completes the puzzle. I now understand and I so appreciate all you have shared.
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