I would like to check some of the batteries in my drawer for their
1. How much of a voltage drop is allowable for a battery to be
considered "still good," for example I note that slightly used AA's are
down to about 1.4 volts?
2. Is their a percentage drop that could apply to all batteries - say
10% or so - or are there different threshholds for AA's, C's, and D's?
Many thanks in advance.
That depends on the type of battery, and to some extent the tester.
Some would be gone by 1.4V and others fully charged are ready to go at 1.3V
I suggest you use a set until they no longer function as you would like
and then test them. Try testing some when they are about half way there to
see if you can measure any meaningful difference.
Usually the best test is testing them under load. Not convenient, but
it is generally better.
This is Turtle.
I got on a kick one time of checking the battery voltage when the low
battery lite come on to my volt and amp meters. When ever the low battery
lite came on. i would take them out and put fresh ones in there and check
the voltage. Everytime on 1.5 volt type batterys they would read 1.45 volts
to 1.49 volts but this would very because of time in between time lite came
on and when you checked them. I have seen this. everytime you see less than
1.5 volts out of a 1.5 volt battery. It does not work well at all in my
Auto car batterys are the same. If you see less than 12 volts out if a auto
battery / unconnected from car and has sit with no use for 5 minutes. It is
bad. You can take a car battery and draw it down to nothing with your head
lites on over nite and the next morning disconnect the battery from the auto
and let it sit for 30 minutes with no use and you will see 12.0 to 12.6
volts if it is good. If it killed it or hurt it, you will see less than 12
volts, even when it is not able to do anything. Just getting carried away
Sure you can. But whether they will operate an appliance
depends on the appliance. I've been checking rechargeable
and other batteries for years. And no you don't need to
worry about voltage drop under load if you are using
relatively low draw appliances such as radios.
In general, fresh, fully charge batteries run upto 1.6 volts
per cell. That is a 1.5 v battery (which is a cell) should
read about 1.56 to 1.59v when new. At 1.35 volts those
batteries won't run my Walkman. Flashlights are different,
but the light will be pretty weak at 1.35 volts also. I
replaced an old 9v battery in a smoke alarm that read 6.8
volts and was still working, but I think that is pretty
unusual as the current draw is minuscule.
For your purposes, you don't need to worry about current
draw and voltage drop under load. If the battery reads 1.45
or above at rest, chances are that it will work fine for a
while. If it reads 1.35 or below, it's dead or will be
shortly; between 1.35 and 1.45, it's weak but may operate
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