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21700 Batteries, are they better than 18650 batteries?


What is a 21700 battery?

21700 batteries are rechargeable lithium-ion cells that are used to power various devices like flashlights and vaping accessories. Similar to other lithium-ion cells, the 21700 battery is named after their dimensions to identify size and compatibility quickly. The exact size is 21mm in diameter and 70mm in length. One crucial factor to remember is that 21700 batteries can be both protected and unprotected.

For this reason, it is essential to do your research when choosing brands; some may provide both protected and unprotected cells. Many people consider 21700 batteries an upgrade from the usual 18650 battery that you see in flashlights or other high drain devices. These batteries have even been used to power hybrid and electric vehicles.

Fenix 21700 Battery

What is the difference between a 21700 battery and a 18650 battery?

Many wonder what the most significant difference between a 21700 battery and a 18650 battery. From a physical aspect, it is simple; the size is the difference. 21700 batteries are slightly larger than 18650 batteries. Both come in flat top and button top forms. However, one is smaller than the other. Being that the 21700 battery is slightly larger, it will also provide more energy/power and runtime. One thing to consider here is the mAh of these batteries. mAh's on 18650 batteries will range from 2000 up to 3500. On 21700 batteries, you can expect mAh's to range between 3000 up to 5000 mAh's. You may see advertising for 18650 batteries that claim to have up to 9000 mAH. However, it would be wise to be skeptical of such claims. Batteries that claim to have higher mAh's than what the average is usually are not protected or cannot provide that amount of power. We recommend spending some time doing research and buying a lithium battery from a reputable brand.

Are all 21700 Batteries the same?

No, not all 21700 batteries are the same. Some of these lithium-ion cells may be protected, while others may be unprotected. Most protected 21700 batteries include PCB and overheat protection. These protection methods help the battery from overcharging or overheating. Unprotected batteries are more dangerous since they do not have this preventative protection. Two other differences in 21700 batteries are the build and mAh's. Some 21700 cells will come in flat to versions, while others will go in now button top versions. They also have different ranges of mAh's, some lower some higher.

Other than flashlights, what other products use 21700 batteries?

Many products use 21700 batteries, including cars, electric bikes, and vapes. Since 21700 batteries can provide more power, they are becoming a more conventional battery among electronics, including flashlights. Longer runtimes on various electronic devices have gained the attention of many modern companies. Fenix, a flashlight manufacturer, currently has three flashlights that are 21700 battery compatible that were released this year. These new flashlights have higher lumen outputs and longer runtimes compared to there 18650 flashlight predecessors. The Fenix PD36R model even has a USB type-c port so you can charge the 21700 inside the flashlight, no need for a separate charger.

PD36R Flashlight 21700 Battery compatible

Fenix also sells 21700 batteries. Currently, they have the 5000 mAh model, which is priced at $24.95. This battery has protection circuits that prevent overcharging the battery over-discharging the battery and short circuit. The Fenix 21700 has a maximum current of 7.5 amps and a voltage of 3.6. If you purchase either the Fenix PD36R Flashlight or the TK22UE, the 21700 battery will be included.

Before using a 21700 battery from any provider for your devices, we recommend carefully reading all instruction manuals. As we had mentioned before, most 21700 batteries are very similar in size. However, internally, these batteries can be completely different. Some may differ in voltage, charging current, and or PTC protection. Some electronic devices may only accept 21700 cells that have a guaranteed maximum current or voltage, and going over can harm the device. If improper batteries are used in your electronic equipment, the warranty may be voided. 

If you do have any questions about any of our batteries including the 21700, please contact us. We will be glad to provide you with the answers you need to operate these batteries safely. 

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