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Can voltage alone be a qualification for a cell ?

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Externet

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Hi.
Can a cell be qualified by its voltage ?
The battery for a device uses 4 AA cells in series. I installed 4 different brands to make it work (because that is what I happened to have left in my new cells bin). Rayovac, Energizer, Duracell, Eveready.
After months of normal use, the device started to fail with the typical behavior of spent batteries. Measuring each, 3 of them showed near 1.4V; one was 0.7V
Replaced only that 0.7V worst one and the device worked for a few more months until behaved the same. Only one of the cells was really low in voltage again.

Did the battery pack tell which cell of the four was the worst performing and least durable brand ? And then the next worse ?

Replacing only the worst cell every time, can a grading of quality be discerned (for that particular consumption rate/usage) or something else has to be considered ?
 

Cell discharge profiles vary between technologies, with construction,
etc. In an application with current draw, you care about voltage @
load more than open circuit voltage, which if discharge affects series
resistance faster than backing voltage might tell you nothing.

Short circuit current and open circuit voltage together tell you a lot
(including whether your shorting wire or some internal battery
element is a fuse, or in the case of some lithiums, an igniter?).

But as a practical matter a series load resistor that represents the
normal use load, through a current meter suited to same, will be
a one step qualification. Then, so too could be a roughly-right
incandescent bulb.
 
Hi,

how have you determined the battery voltage? If you used a DMM and measure at the battery poles while no load is connected, gives you less information about the internal resistance of the battery. Consequently, you do not know the actual voltage at the battery poles when supplying a load (voltage drop across Ri). I have a DMM which sinks 20 mA in battery voltage measurement mode, to give a more meaningful result. Of course you can simply use a resistor to achieve that. E.g. a ~100 Ohm.

BR
 

I know that when I bother to read product manuals I often find that
the manufacturer instructs you not to do what you have done, for
reasons such as what you describe.
 

Hi,

Does the cell voltage alone give information?
It depends on several things:
* what information you expect
* test conditions
* battery chemistry

Say you have an AAA cell.
The measurement (unloaded) shows perfect 1.5V at room temperature
--> tells about nothing. It may be brand new and fully charged. It may be at low charge level, it may have high internal resistance.

Now .. you load it with 150 Ohms and it shows 1.1V on an alkaline type.
--> Gives a clear answer: it's dead.

So you may be able to detect "end of live", but you can't detect charging state, age, health state

Klaus
 

Does the cell voltage alone give information?
It depends on several things:
* what information you expect
* test conditions
* battery chemistry
Thanks.
Unable to probe each cell with the device running. Had to remove and read each cell no-load voltage out of circuit.
The information expected is which brand dies first to avoid such.
No test conditions, only the gadget running until its 'low battery' shows.
Cells chemistry is plain vulgar carbon-zinc for each, no alkalines.

Understood mixing new and used cells is not convenient, but gave me the opportunity to explore what would happen, which would die next.
Mixing brands of all new cells not considered as wrong. Gave me the opportunity to compare them.
 

Thanks.
Unable to probe each cell with the device running. Had to remove and read each cell no-load voltage out of circuit.
The information expected is which brand dies first to avoid such.
No test conditions, only the gadget running until its 'low battery' shows.
Cells chemistry is plain vulgar carbon-zinc for each, no alkalines.

Understood mixing new and used cells is not convenient, but gave me the opportunity to explore what would happen, which would die next.
Mixing brands of all new cells not considered as wrong. Gave me the opportunity to compare them.
This is, in my opinion, a waste of time. All you’re accomplishing is showing which battery lasted the longest in one particular condition. You only sample one of each battery, you don’t know how long any of those batteries sat on the shelf, what conditions they were exposed to prior to your use, and so on. It’s not a very scientific test. In the end, what significant information do you have?
 

In the end, what significant information do you have?
Was not intended to be a scientific test, just using the opportunity of a situation of different brand cells in the exact same drain application. As significant information ; I will not buy ´Eveready´ brand AAs. That, I did not know before.
 

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