18650 Batteries: What are they? Fake vs Name Brand?

18650 Batteries, or batteries who roughly measure 18mmx65mm, are kind of misnomers for rechargeable batteries that are very close to the 18650 size. What they all have in common is that they’re lithium-ion and usually power high drain devices with 3.6v or 3.7v.  You’ll find these in vapes, flashlights, fitness devices, specialty machines, and other types of devices and lights.

The performance, or capacity is usually around 1800mAh-4000mAh with 3.6v-3.7v. Very common to see these in laser pointers, laptops, camera accessories as well.

Picking the Perfect 18650 Battery

Since 18650 batteries are not all built equally by a standard manufacturing guideline, it can be challenging at first to know what battery is perfect for the job.

The amp capacity or, continuous discharge rating, is an important trait in 18650 batteries. Amp capacity is measured in amps (a) and can be drawn from the battery without destroying or heating the battery too high.  It’s a good idea to match the draw from your device to the CDR of the battery.

Choosing the wrong CDR/18650 Battery can cause damage to the battery. Damage can shorten the batteries life, or even worse catch fire.

One helper of a fail-safe in 18650 batteries is the relationship between A and mAH, batteries capacity.  Higher capacity batteries such as a 3500mAh will have a lower CDR.


Button Top or Flat Top 18650 Batteries

Again, Batteries are not standardized, so it’s important to note which you have or need to replace. There’s a slight bump on the positive side (or maybe even perfectly flat!), or maybe even a button. It’s very slight, but the extra mm makes a difference in fitting or not fitting. There’s a plus though! If it’s spring-loaded, good news! The new 18650 Battery will probably fit regardless. Now it’s a determination of voltage and CDR.

18650 Flashlight Battery in Use

18650 Flashlight Battery in Use

Protected 18650 Batteries

Since these batteries are not standardized it’s critical to know if you need a protected battery. A protected 18650 battery has a protected electronic circuit built into the battery. It’s visible and protects the 18650 battery from excess charging, discharging, short circuiting, hot conditions, and helps to generally keep the battery from leaking and exploding.

Many protected batteries also have a valve which disables the cell permanently if the pressure becomes too high inside the cell. This is commonly what happens when batteries swell, at which point they're more susceptible to igniting

Streamlight 18650 3.7v 2600mAh Battery SL-B26 Protected

Unprotected 18650 Batteries

Unprotected 18650 Batteries lack the defense circuitry, and thus can’t prevent over charging, discharging, and extreme temperatures. As a result, unprotected 18650 batteries are more affordable than protected 18650 cells.

Take note: Do not leave unprotected on the charger for too long, keep the contacts covered, and pay attention to the CDR rating so you’re not drawing excessively from the battery.

Fake 18650 Batteries

Many Amazon and Walmart 18650 Batteries are unregulated from unauthorized sellers. It’s not rare to buy a cell and wrap it in a familiar brand. If you buy a battery for a high-powered device believing it to have an adequately safe CDR, you could injure yourself or damage your device when the battery turns out to have an entirely different rating. Popular and trusted brands describe weight, CDR, and accurate spec’s of the batteries they sell. Use any and all of these measurements when choosing your 18650 battery salesman.

Trusted and Popular 18650 Batteries:


Samsung 30Q 18650 3000mAh 15A Battery (Flat Top)

Samsung 30Q 18650 3000mAh 15A Battery (Flat Top)

Samsung 30Q 18650 3000mAh 15A Battery (Flat Top)


Hohm Tech Life V4 18650 Battery

Hohm Tech Life v4 18650 Battery

Hohm Tech Life V4 18650 Battery


Lishen 21700 12A Battery 4000mAh LR2170SA


21700 Battery Samsung 40T

Samsung 40T 21700 4000mAh 35A Battery (40T3)


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