What is the Voltage of AA Battery?

Blog | Published by Alex on July 22, 2025

The AA Battery Voltage

AA batteries are one of the most commonly used power sources in household and industrial applications. Understanding their voltage characteristics is essential for proper device compatibility, performance, and safety.
AA batteries are classified as LR6 or R6 type under the IEC standard. Their typical dimensions are as follows:
1. Diameter: 14.5 mm
2. Height: 50.5 mm
All AA batteries maintain a consistent physical size to ensure compatibility across various devices.

Nominal Voltage of AA Batteries

The AA voltage (nominal voltage of a AA battery) varies depending on the battery chemistry:
1. AA Alkaline battery voltage: 1.5V (Common)
2. Zinc-carbon AA battery: 1.5V
3. Nickel-metal hydride (NiMH) AA battery: 1.2V
4. Nickel-cadmium (NiCd) AA battery: 1.2V
5. Lithium AA battery (Li-FeS2): 1.5V or 3.6V (for Li-ion variants like 14500)

Fully Charged and Cut-off Voltages

Different chemistries also have different full-charge and end-of-discharge voltages:


Note: Li-ion 14500 cells are the same size as AA but output much higher voltage (3.6–4.2V). They are not suitable for standard AA battery devices unless specifically supported.

Discharge Behavior

1. Alkaline batteries have a gradual voltage drop during discharge.
2. NiMH batteries maintain a more stable voltage near 1.2V until near depletion.
3. Lithium batteries (Li-FeS2) offer long life and high energy density, with relatively stable output.

Application Considerations

1. Devices designed for 1.5V AA batteries may not function properly with 1.2V rechargeables unless they have low voltage tolerance.
2. Always check the device specifications when using 14500 lithium AA-sized cells to prevent overvoltage damage.

Highlights

The voltage of an AA battery depends on its chemistry. While the standard nominal voltage is 1.5V, rechargeable versions like NiMH and high-capacity variants like Li-ion differ significantly. Understanding these differences ensures safe and efficient battery use across applications.

What happens if the voltage of an AA alkaline battery is reduced to 0V?

Reducing the voltage of an AA alkaline battery to 0V means its internal energy is almost completely depleted, but this can lead to battery leakage, swelling, or even corrosion.

1. Complete consumption of chemical reactions
(1) The normal voltage of an AA alkaline battery is 1.5V; when it drops to 0V, it indicates that the internal zinc and manganese dioxide have almost completely reacted;
(2) The battery can no longer supply power.

2. Risk of extreme over-discharge
Continuing to discharge the battery to 0V (especially under high current load) may cause:
A) Electrolyte decomposition → gas generation → swelling;
B) Casing rupture → electrolyte leakage (such as potassium hydroxide);
C) Corrosion at the bottom of the battery or around the positive cap, leaving white crystals or alkaline liquid.

3. Harmful to devices
(1) The leaked alkaline substances are corrosive and can corrode the battery compartment, circuit boards, and metal contacts;
(2) In severe cases, the entire device may be damaged.

Summary:
After the voltage of an AA alkaline battery drops to 0V, the battery may be damaged or leak due to over-discharge. Therefore, it is recommended to stop using the battery and properly recycle it once the voltage drops below 1.0V to protect devices and the environment.

What happens if an AA alkaline battery is left unused for a long time?

Even if not used, an AA alkaline battery left unused for a long time (such as 10 years) may undergo self-discharge, eventually leading to chemical decomposition inside, resulting in corrosion and electrolyte leakage.

Self-discharge phenomenon
Alkaline batteries slowly self-discharge, and their voltage gradually decreases, meaning they will "run out of power" even if unused.

Aging caused by long-term storage
(1) Internal materials and electrolyte chemically change over time, and the metal casing may react with the electrolyte, causing corrosion.
(2) The sealed structure may swell or even rupture due to gas buildup.

Electrolyte leakage risk
When internal pressure increases or sealing fails, the potassium hydroxide electrolyte inside the alkaline battery may leak out, corroding surrounding devices or battery compartments, and contaminating the soil.

Impact of storage environment
High temperature and humidity accelerate aging and increase the risk of leakage.

Summary:
the Alkaline double A battery left unused for a long time (such as 10 years) can naturally age, causing corrosion and leakage. It is recommended to regularly check unused batteries or recycle them in time to avoid damage to devices and the environment. By the way, The Call2Recycle, founded in 1994, provides convenient and environmentally friendly battery recycling solutions for North America. It partners with many major supermarkets, electronics stores, office supply stores, community centers, schools, and libraries to set up dedicated battery recycling bins where customers can drop off their used AA batteries for free.

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