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Old Sep 13, 2005, 6:03 PM   #1
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Hi All, I have a voltmeter that I use to check the volts of my aa nihm batteries. What setting on these voltmeters puts the battery under a load that would see how many volts the battery has under a load? Thank you for your help.

Dan
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Old Sep 13, 2005, 8:22 PM   #2
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Voltmeters are designed generally to NOT load circuts under test, so you should use either a tester designed specifically to test batteries, or use an separate resistive load when testing. A fixed resistor of about 10 ohms should provide enough load to tell the cell's condition.

brian
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Old Sep 13, 2005, 9:50 PM   #3
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VTphotog wrote:
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Voltmeters are designed generally to NOT load circuts under test, so you should use either a tester designed specifically to test batteries, or use an separate resistive load when testing. A fixed resistor of about 10 ohms should provide enough load to tell the cell's condition.

brian
absolutly, the volmeter has a super high ohm value and wont draw much off a battery.
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Old Sep 14, 2005, 8:42 AM   #4
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Hello Dan,

Several people have tried battery testers from these people.

http://www.ztsinc.com/main_products.html

They have been very happy with their results.

Tom
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Old Sep 21, 2005, 9:58 AM   #5
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You could go for the throat as a test. There are 4.8 volt 750 ma bulbs on the market. If you connect three in parallelgiving a total current consumption of 2250 maand use four 2300 ma nimh`s then see if your batteries can stand the strain, I think not. So the makers are not being very truthful. If a transformer maker states his transformer is 12 volts at 24 voltamps it is another way of saying it is rated at 12 volts at 2 amps. So why should battery makers over state their batteries power.
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Old Sep 22, 2005, 9:22 AM   #6
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Hello Geriatric,

There are standardized procedures for rating battery capacity. I have found that (for the most part) if you follow those procedures during testing, you end up with very similar results to what is listed as the battery capacity.

The problem is that the test procedures do not reflect "actual" use. Energizer, Duracell, GP, Sanyo and a few others will show how their cells hold up under higher loads, but you have to dig a little to find out this information. It also helps if you have a working understanding of the terminology and methods used in the test reports.

The other side of this is that bigger numbers sell. Most people would rather purchase a battery that is labeled as 2500 mAh, rather than one that is listed 1950 mAh under a 2000 mA load.

Tom
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Old Oct 3, 2005, 9:28 AM   #7
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You would really need to test the batteries with some sort of constant current load, testing with lamps is not that ideal, as when a lamp is "cold" its filament resistance can be up to one sixth of normal. That means when voltage is first applied to the lamps, the startup current required to get the lamps "hot" can be up to six times greater than the rated "running"amperage of the lamps...



So a set of 4 batteries may not be able to provide enough startup current, but they could run them fine if they were already "on" when you started applying battery power.




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Old Oct 3, 2005, 12:39 PM   #8
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dekelsey61 wrote:
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What setting on these voltmeters puts the battery under a load that would see how many volts the battery has under a load?
If you shop around, you'll find a DVM that has a "battery test" range. Usually there are two, for 1.5V and 9V cells. One like this will cost you about twice as much as a vanilla DVM, but neither is very expensive (5 pounds to 10 pounds in UK 'Maplin' shops, roughly equivalent to 'Radio Shack'.

These ranges put a load on the cell and display the current passed. On my 'Caltek' instrument, a "battery working fine" reading is supposedto be 40mA, across a 37 ohm load. This refers to a 1.5V disposable AA cell. I find that 36 or 37 mA is about right for a fully charged AA Ni-MH.

If you have an instrument like this, you don't have to mess around with resistors, crocodile clips, and so on.

Good luck, Alan T
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Old Oct 6, 2005, 8:06 AM   #9
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Hi,



I found a similar device here in Switzerland, it cost me 5 Swiss francs or about 4 USD. It is a fully working digital voltmeter with 3.5 digit LCD display. It runs on 2 LR44 batteries (included) in the price. It has 3 setting for loading of the battery, 1st postion 2.5 -20mA for small batteries, next is 20-120 mA and last position is about 75 mA (at least)

It is a neat device, there is retractable arm to connect the battery (no dangling cables), because it is so cheap, I bought 4 units. The 2 units I bought just for their batteries for my laser pointer . The batteries in Switzerland cost about 4 SFr each, the batteries that comes along the unit would already cost 8 SFr.


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Old Oct 6, 2005, 7:18 PM   #10
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juandelacruz, Thank you for your reply. The device you are talking about is what I am looking for. Can I buy any in the US? If so, what website can I go to buy one. It sounds like a nice device. Thank you for your help.

Dan
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