18650 vs AA
Battery Comparison

Feature 18650 AA
Diameter 18mm 14.5mm
Length 65mm 50.5mm
Nominal voltage 3.6-3.7V (Li-ion) 1.5V (alkaline, single usage) or 1.2V (NiMH, rechargeable)
Typical capacity 2,000-3,500 mAh 1,700-2,500 mAh (alkaline); 2,000-2,500 mAh (NiMH)
Weight ~45-48g ~23g (alkaline); ~26g (NiMH)
Rechargeable Yes (hundreds of cycles), rechargeable Only NiMH/NiZn variants; standard alkaline is single-use
Common chemistries Li-ion (NMC, NCA), LiFePO4 Alkaline, NiMH, NiZn, lithium primary
Device compatibility Flashlights, laptops, power tools, e-bikes, vapes Remotes, toys, clocks, cameras, household electronics
Cost per cell Higher Lower (especially alkaline)
Cost per mAh Often lower over time (reusable) Higher long-term if using disposables
Availability Common in electronics/hobbyist stores Extremely widespread, sold everywhere
Interchangeability Not compatible with AA devices without a voltage-converting adapter Not compatible with 18650 devices; different voltage and size