AA and 18650 batteries are very similar and cylindrical batteries. So people are wondered if these batteries can be used interchangeably to simplify finding replacements for devices. But there are differ in some characteristics such as size, battery chemistries, battery voltage, capacity, and other charging/discharging features.
18650 batteries are slightly bigger than alkaline AA batteries, with around double the standard voltage. Also 18650 batteries cost more than AA batteries.
What is 18650 battery?
The 18650 battery size is about 18 x 65 mm. It is slightly larger than an AA battery, have a nominal voltage of 3.2 to 3.7 volts, and a nominal capacity of 1800 to 3500 mAh.
Usually the 18650 battery needs to work with the BMS together to avoid overcharging and overdischarging the battery.
In addition, 18650 cells also differ in the physical shape of the anode. Some batteries have a flat tip, while others have a tip shape.
In addition, the 18650 battery has no memory function and can be charged and used at any time without a full charge.
What is AA battery?
AA batteries are smaller than 18650 batteries in size, only about 14 x 50 mm. The standard AA battery has 1.5 volts nominal voltage. And a capacity ranging from 1800 to 2700 mAh.
However, the chemistries of rechargeable and non-rechargeable AA batteries differ. While there are now rechargeable AA batteries available such as AAs made from Li-ion, NiMH, or NiCd. But the typical AA batteries people talk about are often non-rechargeable.
Difference between 18650 battery vs AA battery?
Dimension
Just from the appearance, 18650 battery and AA battery have obvious size difference. The 18650 lithium battery has a diameter of 18mm and a length of 65mm. In comparison, AA batteries (Also known as 14500 batteries) are 14mm in diameter and 50mm in length. Therefore, the size and diameter of 18650 batteries are much larger than AA batteries.
Chemistry
The 18650 battery is a specific size rechargeable lithium-ion battery. Usually made of lithium iron phosphate or NiCoMn ternary material. And AA batteries can be alkaline batteries, zinc-carbon batteries, nickel-cadmium batteries, nickel-metal hydride batteries (NiMH) and lithium-ion batteries.
Voltage
The voltage is not the same between 18650 and AA. An 18650 battery has a nominal voltage of 3.7 volts, while an AA battery has a voltage of 1.5V. Their voltages are at different levels.
Capacity
At present, the capacity of 18650 battery is 1800~3500mAh, the capacity of AA lithium-ion battery is 1700~2700mAh, and the capacity of alkaline AA battery is 600~2700mAh.
Performance
Overall, the 18650 battery has a higher capacity and therefore can store more energy. It can be used for a longer time after a full charge. However, AA batteries have a much lower capacity, but are generally not rechargeable and can be used after a single use.
Lifespan
AA Alkaline batteries are usually disposable and not rechargeable. The 18650 battery can charge/discharge about 800-1000 times.
Can we replace AA battery with 18650 batteries?
Apparently you can’t replace 18650 batteries with AA batteries. Because the voltage of 18650 is significantly different from that of AA batteries. 18650 batteries have 3.7 volts, while AA batteries have 1.5 volts. However, the 18650 battery is interchangeable with the 21700 battery, which is a rechargeable Li-Ion AA battery with the same voltage.
Where I can find the rechargeable lithium AA Batteries?
Just as we mention above, the AA battery size is D14mm and H50mm basically. Our ELB 14500 lithium battery is specially designed to replace AA battery. Due to the inconsistent internal chemical composition of lithium battery and alkaline battery, the voltage of ternary lithium battery is 3.6V, while the voltage of alkaline battery is 1.5V. so we need add a step-down PCBA inside the battery to make the voltage drop of the lithium battery to 1.5V. If you interested on this, welcome to consult our technical team for assistance.
Which battery is better? 18650 Battery vs AA battery?
In terms of commercial popularity, AA batteries are ahead of 18650 batteries. Because AA batteries have been popular for more than 20 years, and 18650 has only been popular for less than ten years. But in the application potential of this one, obviously the 18650 battery has more advantages. Tesla uses 18650 as the battery for model Y, and basically all electric motorcycles and scooters use 18650 batteries.
Related article
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3. Related article 《18650 vs 14500 Battery: Complete Comparison Guide》
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