14500 Battery vs AA! Same Size? Replacement? Flashlights or Anything

Are 14500 Batteries and AA Batteries the same?

No, but almost.

They are almost the same size, but if the 14500 has a protected circuit which will make it longer.

14500 is 14mm x 50mm

AA is 13.5-14.5mm x 49.2-50.5mm

They also have different capacity and voltage.

Since these batteries are very similar in size some electronics include the ability to run off of both voltages

So lets see what the 14500 Battery vs AA battle is all about.

14500 Battery Vs AA Match Up

14500 Battery Basics

Using the term 14500 battery is pretty specific.

First it is referencing a rechargeable lithium ion battery which are the core of most rechargeable flashlights. There is a wide range of chemistries for li-ion batteries but they all are based on lithium ions moving from the negative electrode through an electrolyte to a positive electrode while discharging. They move back when recharging.

All 14500 batteries are li-ion batteries but not all lithium ion batteries are 14500, this is just one of the sizes.


The battery number 14500 actually talking about the dimensions of the battery in millimeters.

14mm in diameter and 50mm tall.

Electricity Profile

14500 batteries have a cell voltage of 3.6-3.7V which is the average voltage during a complete discharge. During the discharge the range is from 4.2V to 2.5V but in general you should not go below 3V for the health of the battery.

Capacity and Discharge Rate

Capacity is measured in milliamp hours (mAh). 14500 batteries currently range between 600 mAh to 1600 mAh.

Discharge Rate is measured in amperes (A). 14500 batteries currently range between 1.6 A to 6.5 A

Capacity and Discharge rate play different sides of the same coin, if discharge rate is high then capacity is low and vise versa. For flashlight enthusiasts that like super high brightness levels high amps are better. These would be IMR batteries.

But, if you are looking for long battery life then something with high capacity and low amps would be good.

One thing to keep in mind with li-ion batteries is that they have a self discharge rate of around 10% per month. So, these are not batteries that you want to store or put in devices that just sip power since the battery will just die in a couple of months either way.

But, in this specific case of AA and 14500 we need to note that li-ion batteries have a way slower self discharge rate than NiMH. We mention this since there are some 14500 makers that put a voltage limiter to set the voltage at 1.5 V. In this case they could be a better option than AA NiMH rechargeable batteries.

One of the biggest benefits of li-ion rechargeables is that they can be recharged over 1000 times and they do not have a memory issue. You should be able to recharge them to the highest capacity they whole time.

AA Battery Basics

In the past A batteries were a specific size, volts, and chemistry. Once electronics got smaller and battery technology progressed sub-A size batteries were developed and that is where AA, AAA, and AAAA batteries come from.

Now days AA on a battery is talking almost strictly about the size.

You can have AA alkaline batteries, lithium batteries (not li-ion), and Nickel based rechargeable.


The size of an AA battery is between 13.5-14.5mm in diameter and between 49.2-50.5mm tall, including the button top.

Electricty Profile

AA batteries have a cell voltage of 1.5V. During the discharge the range is from 1.5V to 0.9V but in general they will not work below 1V.

Capacity and Discharge Rate

Alkaline batteries have a capacity between 1700-2850 mAh while Ni-MH have a capacity between 600-2750 mAh

The voltage of AA batteries by standard is 1.5 Volts.

But devices made to run on AA batteries are usually fine with 1.2 Volts since popular Nickel-Cadmium (NiCd) and Nickel-Metal Hydride (NiMH) rechargeable batteries in the AA size are 1.2 Volts. There are lots of types of batteries.

A great thing about old school Alkaline batteries is that they have a super low self discharge rate of 0.3%. So they can be used for prepper situation or to just keep in a drawer.

On the other side of the AA spectrum Ni-MH which are our favorite rechargeables at this size have a self discharge rate of 20% per month. So after 4 months or so you are super low anyway. These batteries are great for things that kill batteries really fast anyway.

One more thing to keep in mind with Ni-MH is that the batteries have a memory so if you do not discharge and recharge them correctly you will lose capacity over their 500 to 800 recharges.

Difference Between 14500 and AA Batteries

Both of the names are referencing a size and these sizes are almost the same. Another thing is that 14500 is always talking about a li-ion rechargeable battery where AA can be a primary battery or a rechargeable battery.

14500 batteries do not have a memory effect as they recharge so you will have high capacity the entire time. While Ni-MH have a memory effect so as you cycle them you will lose power.

Can I Use AA Battery Instead Of 14500?

If a device is asking for a li-ion 14500 battery then it is expecting somewhere between 3 to 4.5 Volts to run. AA batteries run between 1.2 to 1.5 Volts.

So, unless the device specifically says that it can run off of both power sources it will not be possible.


So can you use one in place of the other?

The answer is… Sometimes.

Especially in flashlight where the manufacturers know that many flashlight people will be familiar with Li-ion technology. Most other places if a device is asking for a AA it will not be able to take a 14500 battery since the circuit will not handle the 3.7 volts.

Manufacurers will even tout it as a selling point, it will say that it is a duel fuel system and they will obviously show you the lumens from the 3.7 volt li-ion battery.

Last, there are some battery makers that are putting a voltage limiter on 14500 batteries so they output 1.5 volts. In this specific case you can use the 14500 in any AA device and you will have a nice rechargeable without memory and a lower self discharge than NiMH.

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