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I have 17 old AA rechargeable batteries and would like to figure out the fastest way to know which AA batteries are at the end of their recharging life.

Currently, I am putting each AA battery into my rechargeable computer mouse, fully recharging the battery and then using the mouse. So far, two batteries have died after 8 hours of mousing. I am currently working on my third battery.

I have a multi-meter and a wall charger. How can I figure out which batteries are at the end of their recharging life quickly?

With regular one-use batteries, I can use the multi-meter to test the voltage. If the voltage 0.2 V below the battery's rated voltage, then I throw the battery away. Would the same work for a rechargeable battery?

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Test the battery under load after charging. For AA and AAA, use a resistor of about 10 ohms, or a small incandescent flashlight bulb, in parallel with the multimeter. NiCd or NiMH cells should be ~1.4 volts, though different cell chemistries may give a range of ~1.35 to ~1.5 V.

Then wait a few days after charging and retest it, because a bad cell may have high internal leakage. Though its initial voltage is fine, after a few days it may drop below 1.3 volts on the above test, in which case I'd discard it (recycling appropriately).

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  • If the requirement is for testing under load, would probing the batteries inside the housing work? That is, leave the batteries in the mouse and just insert the probes to contact the relevant terminals.
    – Lawrence
    Jan 12, 2018 at 10:18
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    The mouse uses just a few mA or even μA, not enough to significantly load the cell.
    – DrMoishe Pippik
    Jan 12, 2018 at 18:23
  • FWIW, I found that 100 ohms is widely recommended for testing household dry cell (AA, AAA, D, 9V.) batteries under load. 4.7K ohms is suggested for button cell loads.
    – Stan
    Apr 26, 2022 at 16:20
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Consider getting a ZTS Multi Battery Tester, which automatically applies a multiple Pulse Load test to the battery to determine its power state.

Testing a cell three times is supposed to help get the most accurate reading.

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