21700 Lithium-Ion Battery

1.What is the 21700 battery?

The 21700 battery is another lithium-ion battery, and the number 21700 denotes the cell size. It comes in 21mm in diameter and 70mm in length. The 21700 battery comes with an ampere power between 3000mAh and 5100mAh.

While compared to 18650 lithium batteries, it is more significant in length and diameter. The  21700 lithium ion battery has a technical design to offer a voltage range between 2.5v to 4.2v and a charging voltage of 4.2v. However, the nominal voltage of 21700 battery  will be 3.7v. The battery requires about 5 hours for a full recharge, but the charging time may vary subject to the charger voltage, amperage, and battery type.

2.How much does a 21700 battery cost?

21700-Lithium Battery Price Trends

The price of a 21700 lithium ion battery or any other battery depends on various factors. The price may vary depending on the brand's popularity, charging and discharging cycles, battery chemistry, power capacity, protective features, etc. On a general perception, the cost of a 21700 battery is between $6.95 to $28.95.

3.What is 21700 battery used for?

Like 18650 lithium batteries, 21700 cells also power many electronic and luminary devices. These batteries are used on flashlights, and electric vehicles. Since these batteries are rechargeable, they can use in all devices that come with built-in rechargers and need a voltage requirement of 3.2/3.7v.

4.How long does a 21700 battery take to charge?

A 21700 battery pack can typically charge within 4 hours; however, the charging time depends on the charger and battery capacity. You can quickly recharge a battery with a fast recharger than with a slow recharger.

These statistics show that you must use a recharger with a higher capacity for quick recharging.

The 21700 lithium ion battery comes with 3000-5000mAh, so you should use a charger matching the battery capacity for fast charging. If you use a 2A charger to recharge a 3000mAh battery, it will take about 2 hours to complete the charging. Similarly, if you use a 1A charger, the recharging timing will be approximately 3-4 hours.

5.How much does a 21700 battery weight?

The weight of a 21700 battery will be between 55gms to 75gms, depending on the technology and capacity.

6.Are 18650 the same as 21700?

A  Comparison of 18650 and 21700 Lithium-ion Batteries

Both 18650 and 21700 cells are not the same. Their physical dimension is different to one another. When 18650 comes with 18mm diameter and 65mm length, the 21700 battery comes with 21mm diameter and 70mm height. The last digit '0' denotes its cylindrical shape. Both are identical in shape, i.e., both are cylindrical. However, 21700 is slightly bigger than 18650; hence,when the battery type is the same, 21700 can offer more power than 18650 batteries.

On the capacity segment, 21700 offers 3400mAh to 5600mAh, while 18650 offers 1200mAh to 3500mAh. Both can provide 3.7v output, but the output current of 21700 lithium-ion battery is more than 36Amps, but 18650 battery offers more than 25Amps.

21700 lithium ion battery has 35% more cell capacity than 18650 batteries. Similarly, the energy density of a 21700 battery also shows an increment of 20%. As per the data released by Tesla, the energy density of 18650 was 250Wh/kg, but when they started using 21700 batter, the energy density registered as 300Wh/kg. The energy density of 21700 battery in volumetric terms stands 20% higher than 18650 batteries.

The volume of a 18650 battery is 16532 cubic mm, and 21700 battery is 24233 cu mm, which means the latter has ~47% more volume. If we consider 10-12% of the volume space used to incorporate the protective features, the 21700 batteries still have room to produce more power. So, considering all these factors, 18650 and 21700 batteries are not the same. Since 21700 battery has extended battery life and high output, it has a better edge over 18650 batteries.

7.Which battery is better 20700 vs 21700?

In the lithium battery segment, bigger batteries have high power delivery advantage than smaller batteries. Bigger batteries will have extended battery life than smaller batteries and a better amp rating. While comparing 20700 and 21700 battery, both have the same length, but one has a 20mm diameter, and the other has a 21mm diameter. Even though both have no considerable difference, 21700 batteries shall have a better amp rating and can discharge 30-45 amps continuously.

8.Can I Use 21700 batteries in my vape?

Can I Use 21700 Batteries for a Better Experience

Yes, you can use 21700 lithium ion batteries in the vaping device. These batteries are the upgraded version of 18650 and 20700 batteries. The 21700 lithium ion batteries are larger than 18650 and 20700, hence can deliver more amps continuously. Many companies are using 21700 lithium ion batteries for their vaping devices.

9.Are all 21700 batteries rechargeable?

What is The Recharging Status of 21700 Batteries

The 21700 lithium ion batteries are rechargeable. Because of this, it has been used in electric vehicles, vaping devices, flashlights, and many other devices that require power to operate.The beauty of 21700 batteries is their size and power delivery capacity. Let us examine a projected situation to understand the convenience of using 21700 lithium ion batteries instead of other batteries.

Suppose you want to run a 9000BTU cooling capacity air conditioner that consumes about 1100 watts per hour; you can run the air conditioner for one hour by using a 21700 battery pack of 74 cells. But to accomplish this task, you must use a 21700 lithium ion battery with 3.7v and 5100mAh that can store 3aH to 5aH power and store about 11–18-watt hours.

①Limits of Recharging

All lithium-ion batteries are rechargeable, and they will have a limited recharge cycle. Due to chemical degradation and oxidation, the battery recharging cycle gets degraded over a period. All batteries do have these issues. The 21700 lithium ion batteries feature 1500-4000 cycles.

② Recharge Frequency of 21700 Batteries

Lithium batteries come with a rechargeable feature, and a 21700 battery will have 1500-4000 recharge cycles. So, your recharging pattern will decide the battery life. When your battery voltage reduces to 3v from 3.7v, you can put it for recharge. Frequent recharging may reduce the life of the battery, but not so for lithium-ion batteries. Because lithium-ion batteries have no memory effect.. Therefore, instead of going for a regular recharge, check the voltage level, and if it drops below 3v, do a recharge. If a lithium-ion battery voltage drip down to 2.5v, the battery may lock by itself, making it impossible to recharge using an ordinary recharger.

10.Which 21700 battery is best?(samsung,lg,panasonic,sony, which is best? )

The Best 21700 Battery Among Samsung, LG, Panasonic and Sony

In the best 21700 battery segment, Panasonic 21700 stands top. The 5000mAh battery shows a continuous discharge rating of 30A and a nominal voltage of 3.7v. Because of the constant high voltage delivery, it reduces battery usage. The rechargeable battery offers 1000+ life cycles, and it can deliver 75 watts. It's high energy density minimizes the battery weight and size. These batteries are famous for their efficiency and can use for an extended period. The battery does not have any memory accumulation issues; hence you can always get a full charge after every recharge.

The LG50 lithium-ion battery is available with an energy capacity of 5000mAh with a nominal voltage of 3.6v is our 2nd preference. The battery can offer a full charge voltage of 4.2v with a variation of +/- 0.05v. With a maximum continuous discharge rate of 7.27A and discharge cut-off voltage of 2.50v, this is an ideal battery for electronic devices that consume low power for an extended period. The battery comes with 500 recharge cycles, but you can recharge it 1000+ cycles if appropriately used. It is an unprotected battery, so it is best to use a protected battery management system.
Our third preference is the Sony lithium-ion battery US21700VTC6A which comes with 4100mAh. It can offer a 40A continuous discharge at a 3.6v nominal voltage and a maximum of 4.2v. It is rechargeable but unprotected. You should use it with a protected 21700 battery pack. With a 9A recharger, it can recharge quickly and can let you have 500+ recharge cycles. It sells for US$9 per piece, and with a 3-year shelf life, it is a good option for using high-drain electronic devices that require minimum discharge rates.

Among various 21700 lithium ion batteries, Samsung 40T (Lithium Manganese Nickel -LiNiMnCoO2) has better market acceptance than the rest of the competitors and is one of the famous brands. The battery comes with 4000mAh and can deliver 25A continuous power discharge with a maximum discharge current of 35A or 45A with a temperature cut off mark at 80°C. It can let you use 75W continuously without any break for an extended period. It comes with 250+ cycles with a 6A charger and can recharge more than 500 times if appropriately recharged. The battery’s market price is about $7.50 per unit.








Panasonic 21700














Sony VTC6A







Samsung 40T







11.Dose Tesla use 21700 battery

①Are 18650 the same as 21700?

Previously Tesla has been using 18650 lithium batteries to power their electric vehicles. Now they are using 21700 cells for new model electric vehicles. As per the data released by Tesla, the energy density of 21700 lithium ion batteries is 20% more than 18650 batteries. The increased energy density is mainly attributed to the size and new battery chemistry.

Another critical aspect of 21700 batteries compared to 18650 batteries are their price. As per the data released by Tesla, the cost is less by 9% compared to 18650 batteries, which was about $185. The cost of 21700 batteries stands around $170. When the 18650 system costs about $171 per MH, the 21700 will be 9% less and may touch about $155 per Zhn.As per industry experts, the component and weight can also be reduced by 10% by using 21700 lithium-ion batteries rather than 18650 batteries. So, if the weight of the battery is less, that will eventually have an advantage over the energy density of the vehicle.

② Tesla 21700 battery

Tesla has been using 18650 batteries for their S and X model vehicles, but for the new Model 3 cars, they are using 21700 batteries. These batteries have 46% more cell volume than 18650 batteries. Also, as per a report released by Tesla, they are 15% more energy efficient. They have a cell capacity of 21.275Wh and show an energy density of ~877.5Wh/L.

12.21700 Lithium-ion Batteries - Final thoughts

The 21700 lithium ion batteries are the best-preferred option for electronic devices and electric vehicles because it comes with ~35% more cell capacity and hence can produce 20% more energy than 18650 batteries. These batteries show moderate resistance to temperature fluctuations and short circuit issues. So, they are ideal for devices that require low power drain for an extended period.

The 21700 lithium ion batteries are rechargeable, and by using quick rechargers, you can get the battery charged to the required voltage level. Another highlighted feature of the best 21700 lithium on batteries is their nominal voltage discharge rates. They can deliver 3.7v on average and can deliver a maximum of 4.2v.

However, while purchasing the best lithium-ion battery, you need to check its mAh and discharge rates, marked as C-rate. If the discharge is too high, then there is no point in having a battery with high capacity. On average, 21700 lithium-ion batteries will have a power capacity of 3000 to 5000mAh, but they should also have a corresponding slow discharge rate.

When the discharge rate is very high, it will drain your battery quickly. So, the best way to ensure the discharge rate is whether the C-rate matches the power capacity. If the power capacity is 3000mAh, then the C-rate should be 30A, and if the power capacity is 5000mAh, then the C-rate should be 50A. Any discharge rate more than the corresponding power capacity will fail to give the expected result. Similarly, check the battery's nominal average voltage level.

Any 21700 lithium ion battery with a nominal voltage of 3v is good if it matches your device’s requirement. So, you must check the nominal voltage requirement before deciding on the battery and make sure the battery can match the voltage requirement with the nominal voltage offered by the battery.All 21700 cells may look the same in their physical appearance because of their size, 21mm diameter and 70mm length. However, their internal chemistry will be different from one another; their power output, continuous discharge rate, maximum power capacity, and voltage may vary according to the brand and model. Some batteries have protected features, and some don't have that feature. Therefore, you must select 21700 battery, matching the device's voltage and power requirement; otherwise, it may damage your device.