I've got a bunch of alkaline cells here, and I'm wondering which of them are going to be any good at all. What should I use as a cut-off voltage when I'm deciding? I have a multimeter, which also has a battery tester (I guess it just puts a bit of a load on them).
From one set I get around 1.4V with the battery tester, 1.45 with the voltmeter. But while that sounds pretty good, I know that in practice they were useless. How much do 'rested' alkaline cells recover after use?
Thanks,
Daniele
Always test cells and/or batteries with a suitable load which will vary with type and size of cell. Under no load conditions your voltmeter is likely to register the basic chemical emf of the cell, and the effects of internal resistance will not be registered. From memory, I think about 1 volt per cell is about right for a NiCd or NiMH cell - measured under load, of course. This rises to over 1.2v when charged, and even higher when being charged.
1.4 under load should be fine. Most electronics will work with them down to about 1 volt. Things like torches or motors might not perform quite as well. ;-)
IME there is no easy answer to this question, but as a rule-of-thumb this is what I do:
A brand new alkaline will register well over 1.5V (between 1.6V and
1.7V) on a high-impedance multimeter off load.A part-used alkaline which has been off-load for several hours and measures less than 1.5V doesn't have much life left.
Down to about 1.4V you'll still get a reasonable amount of use from an Alkaline in low-power devices such as clocks, remote controls and small portable radios, but not in high-power devices such as torches or anything with a motor.
Below 1.4V it is rarely worth re-using the cell and I dispose of them.
9V alkalines get thrown when they are down to maybe 8.5V.For example, a Maglite which takes 2 AA batteries may begin to look a bit dim so you change the batteries. You may find however that there is enough life left in them to power your 2xAA tranny for a week or two of normal use.
As others have said though, the amount of use to expect varies depending on the actual load. These figures of course only apply to alkaline cells and *not* to zinc-carbon or zinc-chloride batteries which have the same nominal voltages but different characteristics. Rechargeables have both different voltages and different discharge characteristics and there are other experts on this group in that field.
Just my 2p.
Hwyl!
M.
Hi,
Half dead alkalines work quite well in clocks, remote controls and other low drain uses.
cheers, Pete.
Martin,
I reckon your voltmeter is reading about 0.15 volts high - alkalines still have usable life left in them at 1.35 volts off load. and I have rarely checked new cells at above 1.60 volts - measured using professional (calibrated) test kit, and at normal UK room temperatures, and my findings are consistent with manufacturers data.......
Nick
If they're small batteries ( i.e. AA or AAA ) then I find that shorting them with the multimeter leads when the multimeter is turned to current gives a good indication of their state. From memory, an AA cell will deliver some
1.5A into a short when newish. Of course, make sure your multimeter can take this current, and only do it momentarily. I used an old AVO meter, the result you get may vary with the internal resistance of your ammeter when set to 'current'.Andy.
IME 1.6 is brand new & falls very quickly to 1.5 stays there for a long while drifting slowly down to 1.45 as it begins to die. Sub 1.4 V is effectively dead.
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