AA Batteries: How to Choose the Right Type

AA (double‑A) batteries share a universal size but differ widely in performance based on chemistry. Use this guide to pick the right AA for your device, budget, and conditions—plus care tips to maximize runtime and protect your gear.

Quick Picks by Use Case

• Very low drain (clocks, basic remotes): Alkaline. Cheap, long shelf life. Avoid zinc‑carbon unless cost is the only concern.
• Frequent use (toys, LEDs, game controllers, keyboards): Low self‑discharge (LSD) NiMH rechargeables. Best cost per use and stable under load.
• High drain or cold weather (camera flashes, pro flashlights, avalanche beacons): Primary lithium (FR6). Excellent power delivery, light weight, works in sub‑freezing temps.
• Emergency storage and go‑bags: Primary lithium for up to 10–15 years shelf life. Keep a charged LSD NiMH set as a reusable backup.
• Devices left unused for months: Primary lithium (lowest leak risk) or remove alkalines during storage.

AA Chemistries Compared

Chemistry	Nominal V	Usable capacity at moderate load	Shelf life	Cold performance	Rechargeable	Best for
Alkaline (LR6)	1.5 V	~1200–1800 mAh at ~250 mA	5–10 years	Poor below 32°F (0°C)	No	Clocks, remotes, occasional use
Primary Lithium (FR6, Li‑FeS2)	1.5 V	~2000–3000 mAh with strong high‑drain delivery	10–15 years	Excellent to −40°F (−40°C)	No	High drain, cold, emergency kits
NiMH Rechargeable (HR6, LSD)	1.2 V	~1900–2550 mAh, steady under load	2–5 years (charged; LSD holds 70–85% after 1 yr)	Fair; prefers room temp	Yes (≈500–1000 cycles)	Daily use: toys, LEDs, controllers
Zinc‑Carbon (R6)	1.5 V	~500–1000 mAh	3–5 years	Poor	No	Only very low‑drain basics
Li‑ion 14500 (special case)	3.6–3.7 V	~650–1000 mAh	Varies	Good	Yes	Only for devices that explicitly support 14500

Important: 14500 cells look like AA but have ~3× the voltage. Do not use 14500 in 1.5 V devices unless the device specifically allows it.

Size, Standards, and Compatibility

• Physical size: ~14.5 mm diameter × 50.5 mm length (IEC standard).
• Common designations: LR6 (alkaline), FR6 (primary lithium), HR6 (NiMH), R6 (zinc‑carbon).
• Weight: ~23–30 g (alkaline/NiMH), ~15 g (primary lithium).
• Most devices accept 1.5 V primaries or 1.2 V NiMH without issue; some battery gauges read NiMH pessimistically.

Runtime Examples (Typical)

Actual runtime depends on current draw, duty cycle, and device electronics. These examples illustrate trends:

• Wall clock (~1 mA): Alkaline: 6–12+ months. NiMH LSD: works, but often shorter due to self‑discharge. Lithium: 1+ year.
• LED flashlight on medium (~250 mA): Alkaline: ~3–6 hours with dimming. NiMH: ~6–10 hours, steadier brightness. Lithium: ~7–12 hours and better in cold.
• Camera flash (high pulse load): NiMH or primary lithium recommended for fast recycle and stable output. Alkaline may slow, heat, or leak when pushed.
• Game controller (~80–150 mA average): NiMH: frequent, low‑cost recharges. Lithium: longest per set if single‑use is preferred.

How to Decide: A Simple Flow

1. How often do you use it? Frequent → NiMH. Occasional/long‑term standby → Alkaline or Lithium.
2. How hard does it pull? High drain or cold → Lithium or quality NiMH. Low drain → Alkaline.
3. Do you want the lowest total cost? NiMH + smart charger pays off if you replace cells monthly or more.

NiMH Rechargeables: Best Practices

• Choose LSD NiMH (often labeled “pre‑charged”).
• Use a smart charger with per‑bay control and −ΔV/temperature termination.
• Keep matched cells together in multi‑cell devices and rotate sets.
• Avoid deep overdischarge; recharge before they are completely flat.
• Long storage: keep ~40–60% charged in a cool, dry place.

Buying Checklist

• Check the chemistry: Avoid “heavy‑duty” zinc‑carbon for anything beyond simple clocks/remotes.
• Look for date codes: Fresher cells perform better and store longer.
• For NiMH: Prefer 1900–2100 mAh LSD for reliability; 2400–2550 mAh offers longer runs but may have shorter cycle life.
• For lithium: Use FR6 (Li‑FeS2) from reputable makers; they are lighter and excel in the cold.

Safety and Device Protection

• Polarity: Insert cells as marked (+/−).
• Do not charge disposables: Only charge batteries designed for recharging (e.g., NiMH).
• Don’t mix: Avoid mixing brands, chemistries, or old and new cells in the same device.
• Leak prevention: Remove cells from devices stored for months. Inspect contacts periodically.
• Transport safely: Keep loose cells in cases; avoid short circuits with keys/coins.
• 14500 warning: 3.7 V 14500 cells can damage 1.5 V devices unless specifically supported.

Environmental Responsibility

Recycle all rechargeable batteries and any depleted cells through local programs. Switching frequent‑use devices to NiMH reduces waste and cost. Tape terminals or use protective cases when transporting cells for recycling.

FAQ

Can I mix different batteries in one device?
No. Mixing new/old or different chemistries causes imbalance, leaks, or poor performance.

Will 1.2 V NiMH work where 1.5 V alkaline is specified?
Usually yes. Many devices perform better under load with NiMH despite the lower nominal voltage; battery meters may read low.

Which AA lasts longest in storage?
Primary lithium (FR6) with 10–15 years shelf life, followed by quality alkaline (5–10 years). LSD NiMH hold a charge for months but should be topped up before use.

Why did my alkaline leak?
Most leaks occur when cells are left exhausted in a device or stored hot. Replace sets together and remove batteries for long storage.

What charger should I buy for NiMH?
A smart charger with independent slots, −ΔV termination, and temperature monitoring protects cells and maximizes cycle life.