Guide · updated 10 November 2026
NiMH rechargeable battery voltage: charged, working and empty
A NiMH rechargeable cell is a 1.2 V cell, not a 1.5 V one. Fully charged and rested it reads about 1.35 to 1.40 V, and for most of its charge it works at about 1.2 V. On the scale of an alkaline battery a healthy NiMH cell looks weak, so it needs a chart of its own.
iPhone and iPad (iOS 17 or later): free on the App Store. Android later.
The chart: NiMH AA and AAA at rest
| Verdict | Voltage at rest | What it means | What to do |
|---|---|---|---|
| FULL | 1.35 V and up | As good as new. | Ready for use. |
| GOOD | 1.28 to 1.35 V | Plenty left. | Ready for use. |
| WEAK | 1.20 to 1.28 V | Most of the charge is used. | Usable, but recharge it soon. |
| RECHARGE | under 1.20 V | Empty. | Recharge it before use. |
Measured at rest, with nothing connected. A reading exactly on a boundary counts as the higher band.
AA and AAA cells share the scale: the size changes how much charge a cell holds, not its voltage.
Wait an hour after charging
Straight off the charger a NiMH cell reads high. Let it rest for an hour before you measure, or the reading tells you more about the charger than about the cell.
How to measure it
- Take the cell out of the device or the charger and let it rest.
- Set the multimeter to DC volts. On a meter without auto-range, pick the 2 V range.
- Touch the red probe to the end with the raised cap (plus) and the black probe to the flat end (minus).
- Hold the probes still until the digits settle, and read the voltage with two decimals.
Why the reading says less than you would like
The voltage of a NiMH cell is flat. In use it drops quickly from the fresh charge to about 1.2 V, stays close to that for most of its charge, and falls away at the end. So a resting reading sorts cells into charged, used and empty, and not much finer than that:
- 1.35 V or more: fully charged.
- 1.28 to 1.35 V: charged and ready.
- 1.20 to 1.28 V: partly used. Recharge it soon.
- Under 1.20 V: empty. Recharge it before use.
A resting reading also cannot show a worn cell. An old NiMH cell can charge to a normal voltage and still run a device for only a short time. To find out how much a cell really holds, discharge it through a known load and record a discharge curve.
Do not use the alkaline chart
An alkaline AA is WEAK under 1.45 V and ready to replace under 1.30 V. A NiMH cell at 1.30 V is charged and ready. The two side by side: AA and AAA battery voltage.
The shortcut in the app
Coming Coming in an app update. It is not in the app you can install today.
The battery tester in TestNMeasure has its own tiles for NiMH AA and NiMH AAA, so the verdict uses the NiMH scale: FULL, GOOD, WEAK or RECHARGE, with the next step. More: Battery tester.
The app you can install today already shows the meter's reading large on your phone, with five stability bars that light when the reading is steady. One tap saves each reading with a label and a note, such as the number you wrote on the cell.
Where the numbers come from
The bands follow the NiMH handbooks of battery makers (Energizer, Duracell), which give the resting voltage of a charged cell and a working voltage of about 1.2 V. They are the bands the app uses. You can also type a reading into the battery checker, or start from the general guide: how to test a battery with a multimeter.
What the app does here, and what it doesn't
| What it does | Plan |
|---|---|
| Pick the battery type and see FULL, GOOD, WEAK or the end of its life from the DC volts, with the next step. | Free Coming |
| A large readout that shows which digits have settled; OL and UL are shown as OL and UL, never as a number. | Free |
| Five stability bars show when a reading is steady. | Free |
| One tap saves the current reading, with an Undo. | Free |
| Add a text note and a short label to any capture. | Free |
Not yet, or not planned
- No load test: the battery tester reads the voltage without load, so it cannot show a car battery's cranking strength.
- Reads what your meter measures; it doesn't change the meter's accuracy or ranges.
Questions
What voltage is a fully charged NiMH AA battery?
About 1.35 to 1.40 V after an hour of rest. Straight off the charger it reads higher. From 1.28 V the cell counts as charged and ready.
At what voltage is a NiMH battery empty?
Under 1.20 V at rest. Recharge it before use. Unlike an alkaline cell it is not finished: it is only empty.
Why does my rechargeable AA only read 1.2 V?
Because that is its normal working voltage. A NiMH cell is a 1.2 V cell, and it spends most of its charge close to that value. A reading right at 1.20 V at rest means it is time to recharge it.
Can I test a rechargeable battery with a multimeter?
Yes. Measure it on DC volts after it has rested and compare the reading with the NiMH chart, not with the alkaline one. The voltage shows whether the cell is charged. It does not show how much charge a worn cell can still hold.
Try it in the demo
A simulation of the app in your browser, with made-up readings: no meter and no install needed.
Get TestNMeasure for iPhone and iPad.
iPhone and iPad (iOS 17 or later): free on the App Store. Android later.
Questions or a meter to suggest? Mail support@testnmeasure.app.
No ad networks, no sign-up.