For AA batteries, alkaline is the cheaper fit for low-drain gear like remotes and clocks, while lithium (Li/FeS2) wins in cameras, game controllers and anything left in the cold. The gap comes from drain: Energizer’s own datasheets show alkaline capacity halving as current rises, while lithium barely moves.
Every figure below comes from Energizer’s published E91 alkaline and L91 Ultimate Lithium datasheets. The capacity numbers are read from their charts, so treat them as approximate.
Why the mAh rating on AA batteries depends on the load
An AA battery has no single mAh number. The E91 delivers roughly 3,000 mAh at a gentle 25 mA, about 2,000 mAh at 250 mA and only about 1,500 mAh at 500 mA.
The L91 holds close to 3,500 mAh across that range and still gives about 3,300 mAh at 1,000 mA. On the same chart, Energizer plots its own alkaline cell near 1,000 mAh at that drain.
Video: Project Farm
Energizer’s digital-camera test shows the difference in practice. The E91 runs out at roughly 90 minutes, the L91 lasts roughly 350.
| Spec | E91 alkaline | L91 lithium |
|---|---|---|
| Chemistry (IEC) | Zn/MnO2 (LR6) | Li/FeS2 (FR6) |
| Typical weight | 23 g | 15 g |
| Shelf life at 21°C | 10 years | 25 years |
| Operating temperature | -18°C to 55°C | -40°C to 60°C |
| Capacity at 25 mA | about 3,000 mAh | about 3,500 mAh |
| Capacity at 500 mA | about 1,500 mAh | about 3,400 mAh |
| Digital camera test | about 90 min | about 350 min |
Source: Energizer E91 (E91NA1018) and L91 (L91GL1222) product datasheets.
Where alkaline still makes sense
At 50 mA, Energizer’s remote, radio and clock test puts the E91 near 57 hours and the L91 near 66. A remote draws far less than that, so the lithium premium buys you very little there.
The drawback is leakage. Energizer’s battery care page tells you to pull batteries from devices you won’t use for long periods and to avoid mixing old and new cells, since both can cause leakage or rupture.
Where lithium AA batteries earn the price
Cold is the big one. Alkaline is rated only to -18°C, which rules it out for a trail camera or a car emergency kit through a Canadian winter.
Lithium has limits too. At -40°C, Energizer’s chart shows the L91 still near 3,500 mAh at 25 mA, but it falls to roughly 1,600 mAh at 250 mA and close to zero at 1,000 mA.
A fresh L91 also rests near 1.8 V, against about 1.6 V for the E91. A simple voltmeter reading therefore tells you little, which is why our guide to battery testers that check under load matters here.
High-drain gear and the limits of any AA
The L91 is rated for 2.5 A continuous and 4 A pulses. That covers flashes and toys, not heating: a pack of AA cells cannot run a real heater, as our look at battery-operated heaters explains.
Coin-cell devices are a separate question entirely; see our CR2032 equivalents guide.
Storing and flying with AA batteries
Energizer says a cool, dry spot at room temperature is enough and a refrigerator is not necessary. Heat is the real enemy, causing capacity loss and leakage.
The L91 contains less than 1 gram of lithium, under the 2 g per-battery limit in IATA’s passenger guidance. Transport Canada says spare lithium batteries belong in your carry-on, never checked luggage.
AA battery questions
Are lithium AA batteries safe in every AA device?
Energizer designates the L91 as a size-compatible FR6 replacement for the E91. Check your device manual, since some makers list approved chemistries.
How long do AA batteries last in storage?
Energizer rates the E91 at 10 years and the L91 at 25 years, both at 21°C. Warmer storage shortens that.
Can I recharge alkaline AA batteries?
No. Energizer warns that charging a battery not marked rechargeable can cause leakage or rupture.
Tricia Nelson writes about technology, science, and how-to guides for 3Zebras. She has a knack for turning dense, technical topics into clear explanations, covering everything from iPhone and Android troubleshooting to the science stories behind the headlines.