AA vs AAA Battery Types: Alkaline, Zinc-Carbon, Lithium and NiMH Rechargeable Compared
AA and AAA battery sizes, LR6, R6, FR6 and HR6 codes, alkaline vs zinc-carbon vs lithium vs NiMH rechargeable, mAh capacities and choosing by device.
AA and AAA batteries are cylindrical cells of the same voltage (1.5 V) but different size and capacity. The real difference lies in the chemistry: zinc-carbon, alkaline, lithium and rechargeable NiMH cells fit the same holder, yet their capacity, high-current behaviour and life differ widely. The right battery is chosen by the current the device draws.
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1. Battery sizes
| Size | Alkaline IEC code | Diameter × length | Voltage |
|---|---|---|---|
| AA | LR6 | 14.5 × 50.5 mm | 1.5 V |
| AAA | LR03 | 10.5 × 44.5 mm | 1.5 V |
| C | LR14 | 26.2 × 50 mm | 1.5 V |
| D | LR20 | 34.2 × 61.5 mm | 1.5 V |
| 9V | 6LR61 | 26.5 × 17.5 × 48.5 mm | 9 V |
An AA cell holds about 2–2.5 times the capacity of an AAA; they do not fit each other's holders. AAA batteries suit remotes and small devices, AA cells suit higher-drain devices.
2. Code letters show the chemistry
| IEC code (AA) | Chemistry | Voltage | Typical capacity (AA) | Rechargeable? |
|---|---|---|---|---|
| R6 | Zinc-carbon | 1.5 V | 600–1,100 mAh | No |
| LR6 | Alkaline | 1.5 V | 2,000–2,800 mAh | No |
| FR6 | Lithium (iron disulphide) | 1.5 V | ≈ 3,000 mAh | No |
| HR6 | NiMH | 1.2 V | 1,900–2,500 mAh | Yes, 500–2,000 cycles |
The same letters apply to AAA (R03, LR03, FR03, HR03). 3.7 V 14500 lithium-ion cells share the AA size but cannot replace a 1.5 V battery; they destroy the device.
3. Battery types compared
| Property | Zinc-carbon | Alkaline | Lithium (1.5 V) | NiMH rechargeable |
|---|---|---|---|---|
| High-drain performance | Poor | Medium | Very good | Very good |
| Shelf life | 2–3 years | 5–10 years | 10–20 years | Low self-discharge types lose 15–30% a year |
| Cold operation | Poor | Falls below 0 °C | Down to −40 °C | Down to −20 °C |
| Weight (AA) | ≈ 18 g | ≈ 23 g | ≈ 15 g | ≈ 27–30 g |
| Leak risk | High | Medium | Very low | Very low |
- "Heavy duty" on a zinc-carbon cell is misleading; it suits only very low-drain devices.
- An alkaline cell gives full capacity at low current; in high-drain use such as a camera flash usable capacity drops below half.
- A NiMH cell is 1.2 V but stays almost flat through discharge, whereas alkaline voltage quickly falls below 1.2 V under load. That is why rechargeables work in most devices.
4. Which battery for which device?
| Device | Drain | Recommended |
|---|---|---|
| Wall clock, remote control | Very low | Alkaline or zinc-carbon |
| Wireless mouse, keyboard, room thermostat | Low | Alkaline |
| Toys, torches, game controllers | Medium to high | NiMH rechargeable |
| Camera flash, two-way radio, wireless microphone | High | NiMH rechargeable |
| Outdoor sensors, door locks, smoke detectors | Low, long-term, cold | Lithium or alkaline |
| Instruments (multimeter, laser measure) | Low to medium | Alkaline |
In any device that eats batteries, a rechargeable cell replaces hundreds of single-use cells over its life.
5. Rechargeables and chargers
- mAh is capacity: a 2,000 mAh cell runs a 200 mA device for about 10 hours.
- Low self-discharge (pre-charged) NiMH cells hold charge for months; choose them for rarely used devices.
- Very high capacity cells (AA above 2,500 mAh) self-discharge faster and have a shorter cycle life.
- Prefer a smart battery charger that monitors each slot and stops when full; simple timer chargers overcharge and shorten cell life.
- Never recharge single-use alkaline or zinc-carbon cells; they heat up and leak.
6. Use and storage rules
- Do not mix old and new cells, brands or chemistries in one device; the weak cell is reverse-charged and leaks.
- Remove batteries from devices stored for a long time.
- The white residue of a leaked alkaline cell is caustic; clean contacts with gloves and cotton dipped in vinegar or lemon juice.
- Store batteries cool and dry, away from metal objects.
- Spent batteries go to a battery collection box, not household waste.
Button cells in watches, calculators and car keys are coded separately: CR2032 is a 3 V lithium cell 20 mm across and 3.2 mm thick; LR44 is a 1.5 V alkaline button cell.
Frequently asked questions
What is the difference between AA and AAA batteries?
Both are 1.5 V. AA measures 14.5 × 50.5 mm and AAA 10.5 × 44.5 mm, and an AA holds about 2–2.5 times the capacity.
What is the difference between alkaline and zinc-carbon batteries?
Alkaline has 2–4 times the capacity, a long shelf life and copes with medium-drain devices. Zinc-carbon suits only very low-drain devices such as clocks and remotes.
Can a 1.2 V rechargeable replace a 1.5 V battery?
In most devices, yes. NiMH holds 1.2 V through discharge while alkaline quickly drops below that under load. A few voltage-sensitive devices may show an early low-battery warning.
How many mAh is an AA battery?
In AA size: zinc-carbon 600–1,100 mAh, alkaline 2,000–2,800 mAh, lithium about 3,000 mAh, NiMH rechargeable 1,900–2,500 mAh.
Why do batteries leak?
Internal pressure builds in a fully discharged cell or one left in a device for a long time and electrolyte seeps out. Mixing old and new cells and heat increase the risk.