The voltages that matter
| Point | Battery | Per cell |
|---|---|---|
| Freshly charged, open circuit | 1.4 V | 1.4 V |
| Nominal (plateau) | 1.2 V | 1.2 V |
| End of discharge | 0.9 V | 0.9 V |
Voltages from Energizer’s NiMH handbook.
What to know
A NiMH cell reads about 1.4 V when freshly charged and settles near 1.2 V, where it stays for most of the discharge before falling towards the 0.9 V end-of-discharge voltage. Energizer’s handbook says voltage can’t determine the state of charge.
Charging and limits
| Charging | a smart NiMH charger, at a 2–3 hour rate |
|---|---|
| Freshly charged, open circuit | 1.4 V |
| Plateau | 1.2 V |
| Discharge cut-off | 0.9 V |
| Charging temperature | 0–50 °C; the warmer it is, the less charge it takes (Energizer) |
From the datasheets and manuals in the sources: the datasheet of your battery or charger comes first.
Tips
To know what a NiMH cell holds, use a charger with a discharge or test mode: it measures the mAh.
Low self-discharge cells keep much more charge on the shelf: eneloop up to 70 % after 5 years (Panasonic), standard NiMH 50–80 % after 6 months (Energizer).
Open in the calculator →Enter the voltage you measured and get the charge with its range.
Other batteries
12 V LiFePO4 battery (4S) 24 V LiFePO4 battery (8S) 48 V LiFePO4 battery (16S) LiFePO4 cell (3.2 V) 18650 / 1S LiPo cell (3.7 V) 2S Li-ion / LiPo (7.4 V) 3S Li-ion / LiPo (11.1 V) 4S Li-ion / LiPo (14.8 V) 6S LiPo (22.2 V) 36 V Li-ion battery (10S) 48 V Li-ion battery (13S) LiHV cell (4.35 V) 12 V AGM battery 12 V gel battery 12 V flooded lead-acid battery 6 V flooded lead-acid battery
Frequently asked questions
Can I tell how charged a NiMH cell is from its voltage?
Not reliably: the voltage stays near 1.2 V for most of the discharge (Energizer). A charger with a test mode, which measures the mAh, can tell you.
What voltage does a NiMH cell show when fully charged?
About 1.4 V right after charging, settling towards 1.2 V; it’s empty at about 0.9 V.
Sources: the makers’ charts and datasheets listed on the calculator page.