18650 Battery vs. AA Battery – What Is the Difference?

AA and 18650 batteries are both cylindrical batteries that can be used to power up gadgets like flashlights. People have wondered if these batteries can be used interchangeably to simplify finding replacements for devices. However, is it a good idea, and what is the difference between the batteries?.

Both batteries are household batteries that differ in some characteristics such as size, battery chemistries, battery voltage, capacity, and other charging/discharging features.

What is the 18650 battery?

18650 batteries are rechargeable lithium-ion batteries that measure 18.6 x 65.2 mm (0.732 x 2.567 inches), have a nominal voltage of 3.2 to 3.7 volts, and a nominal capacity of 1800 to 5000 mAh. Because lithium-ion batteries are sensitive to charging and discharging conditions. Some 18650 batteries have a tiny Battery Management System (BMS) that protects the battery against undesirable events; these 18650 batteries are referred to as “protected 18650” batteries.

18650 Battery vs. AA Battery – What Is the Difference?

What is an AA battery?

The letters on the battery will indicate the size of the battery, as they will describe its width and length. The AA symbol denotes that the battery is 50.5mm x 14.5mm in size. The standard AA battery has a nominal voltage of 1.5 volts and a capacity ranging from 1800 to 2700 mAh. However, the chemistries of rechargeable and non-rechargeable AA batteries differ. 

What’s the Difference Between AA and 18650 Batteries?

The 18650 and AA batteries are different types of batteries utilized to power everyday gadgets in the house. The most typical difference between these batteries is voltage, capacity, and pricing. Highlighted below are the difference between the two batteries:

  • Size: Although the 18650 and AA batteries appear to be the same size, they are not. The term 18650 refers to the dimensions and size of the battery in millimeters. The 18650 lithium battery has a diameter of 18mm and a length of 65mm. In comparison, the AA battery (scientifically known as the 14500 battery) has a diameter of 14mm and a length of 50mm. The 18650 battery is substantially larger than an AA battery in size and diameter.
  • Voltage: The voltage is not the same. the 18650 batteries voltage ranges from 3.5 to 4.0 volts, with 3.7 volts being the most common, while the AA battery’s voltage ranges from 1.5 for the non-rechargeable battery  to 1.2 volts for the reachable battery 
  • Chemistry: The 18650 battery is a rechargeable lithium-ion battery of a particular size, while the AA battery can be Alkaline, zinc-carbon, nickel-cadmium, nickel-metal hydride (NiMH), and lithium-ion batteries 
  • Capacity: The capacity of a device is measured in milliamp-hours (mAh). The current capacity of 18650 batteries ranges from 2000 to 3500 mAh, while AA Lithium-ion batteries have a capacity of 1700-2850 mAh, and alkaline AA batteries have a capacity of 600 2750 mAh.
  • Energy stored: There is a difference between the energy stored by  18650 and AA batteries, with some 18650 versions can store 14.8 (or even more) Wh, while the best AA batteries can only hold 5-6 Wh.
  • Memory effect: the 18650 batteries do not have a memory effect, so they always produce a high capacity when they are used and recharged, while Alkaline AA batteries have a memory effect, they lose power as they are being used and recharged.

Can AA Batteries Replace 18650 Batteries?

It is not possible to replace 18650 batteries with AA batteries. The 18650 has a significantly different nominal voltage and capacity than the AA cell. The 18650 battery has a voltage of 3.7 volts and a current of 3000 milliamp hours, whereas AA batteries have a voltage of 1.5 volts and 1800 milliamp hours. However, the 18650 battery is interchangeable with the 21700 battery, a rechargeable lithium-ion AA cell.


the 18650 and the AA batteries are both cylindrical batteries used to power everyday gadgets. The batteries can’t be used for each other as they differ in terms of physical size and chemical composition but serve an essential role in powering different gadgets. The 18650 lithium batteries are perfect if you want to run high-power electronics that drain batteries quickly. They have no memory and can discharge slowly. However, AA batteries are the way to go if you need to store batteries for a long time. They are only intended for one usage, although they can last for years with proper care and use. Check the manufacturing specifications of your gadgets and the batteries for the right fit for the device.

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