18650 vs 21700 Battery: Similarities & Differences

Catalog

l What is a battery?

l How many kinds of batteries are there in the world?

l Why we need batteries?

l Overview and application of 18650

l Overview and application of 21700

l 18650 vs 21700 which one is better?

n 18650 vs 21700 battery: similarities

n 18650 vs 21700 battery: differences

u Difference in capacity

u Difference in Power disparity

u Example of the difference in power and capacity

u Conclusion

l What is a battery?

What is a battery simple definition? A battery is a device that stores chemical energy and converts it to electrical energy. The chemical reactions in a battery involve the flow of electrons from one material (electrode) to another, through an external circuit. The flow of electrons provides an electric current that can be used to do work.

l How many kinds of batteries are there in the world?

The total number of batteries is likely to grow as new types of batteries are constantly being developed. However, there are no exact statistics on how many types of batteries exist in the world. Numerous types of batteries exist in the world and can be categorised into different types based on factors such as different electrochemical principles, uses and sizes. The following are some common types of batteries:

1. nickel-cadmium batteries (Ni-Cd)
2. nickel-metal hydride batteries (Ni-MH)
3. lithium-ion batteries (Li-ion)
4. lithium polymer batteries (Li-poly)
5. lead-acid batteries (Lead-acid)
6. zinc-alkaline batteries (Zinc-carbon)
7. alkaline-manganese batteries (Alkaline-manganese)
8. silver-oxide batteries (Silver-oxide)
9. zinc-air battery (Zinc-air)
10. fuel cell

Here we briefly generalize Batteries of various types：

Alkaline, Nickel Metal Hydride (NiMH), and Lithium Ion batteries are the most regularly used types of batteries. The use of different metals and electrolytes in these batteries provides them different properties, allowing them to be used in a variety of situations.

a.Alkaline Batteries

The most common type of single-use battery is an alkaline battery. Non-rechargeable batteries are the most affordable type of battery and provide steady discharge during their lifetime, resulting in dependable performance. While alkaline batteries are convenient, their disposable nature means that they are not an environmentally beneficial alternative.

b. NiMH Battery

NiMH batteries were the first to be created as rechargeable batteries. In terms of efficiency and financial impact, this skill is advantageous. NiMH batteries can take a long time to charge and deliver less power the more times they are refilled.

c. Lithium Ion Batteries

Lithium Ion batteries are a more recent advancement in rechargeable batteries that have found widespread use in computers and phones. Although they are more expensive than NiMH at the time of purchase, the number of recharges available means that they will save money over time. Lithium batteries are also popular due to their quick charging and more consistent power delivery over their lifetime.

l Why do we need batteries?

 Batteries can lower your dependency on the grid, save you money, and give you more control over how much energy you use. The main electrical grid or standalone battery systems are also options. Lithium ion, lead-acid, or flow (zinc bromide or vanadium) batteries are the most common types of batteries.

l Overview and application of 21700

The term "21700 battery" refers to a lithium ion rechargeable battery with dimensions of 21 mm in diameter and 70 mm in length.First used in electric scooters and cars like Tesla, this size cell has grown in popularity.

It is currently utilized in both flashlights and vaping.

There are three distinct advantages you should be aware of.

1. A greater capacity for all cells.

Due to its size, 18650 cells can hold a maximum amount of about 3600 milliamp-hours (mAh) of battery power.

The 21700 battery may, however, deliver a maximum capacity of 5000mAh, a 42% improvement.

For e-cigarette or torch users, that translates to up to 142% longer run time on a single charge, which is important for frequent users. Additionally, these batteries still have a diameter of less than 1 inch, thus flashlights powered by them will still fit in holsters and weapon mounts that are 1 inch wide.

2. Reduced price per wh

The 21700 lithium battery system costs $155 per kwh, while the 18650 lithium battery system costs $171 per kwh, according to Tesla's publicly available official figures.

In other words, if 21,700 cells are fitted in the Tesla Model 3, the cost of the battery system can be decreased by around 9%.

In fact, according to our calculations, 18650 requires more raw materials to produce a battery pack with the same capacity, which also explains why it costs more.

For instance, a battery with a 100Ah capacity can be made up of 20 units of 5000mah 21700 cells, but if using an 18650 battery, it must use 30 units of 3300mah 18650 cells.

3. Enhanced battery density

based on official disclosures from Tesla.

The 21700 battery has a close to 300wh/kg energy density.

The 18650's maximum energy density is only 250wh/kg.

In contrast, the 21700 battery has an energy density that is almost 20% higher than the 18650 battery.

How many different varieties of 21700 cells are available?

l Overview and application of 18650

A rechargeable lithium ion battery with dimensions of 18 mm in diameter and 65 mm in length is referred to as a "18650 battery" in shorthand.

They are frequently used in scooters, laptops, flashlights, and other high-power consumption gadgets because of their greater capacity and discharge rate.

18650 cells are also used in the Tesla Model S.

Electric scooters and electric cars like the Tesla became the initial applications for this size cell.

Advantages of the 18650 batteries

The 18650 is still reliable today as it was back when it was first created. There are still many tricycles, scooters, 

and consumer goods that use 18650 batteries. Here are some benefits to consider.

When you take all information listed above into account it looks like the 21700 battery is superior. On paper this is true, but the 18650 remains a strong alternative. An 18650 battery is a little more compact and lighter. The 18650 battery is also more affordable. The amount of flashlights that can handle an 18650 battery is bigger and the 18650 battery is a lot more affordable than its bigger brother. In terms of power and capacity, the 18650 battery is more than enough for the average use of a flashlight.

1. Improved heat dissipation capabilities

The internal architecture of the 18650 and 21700 is depicted in the following image. By way of comparison, it is discovered that the 21700's winding length and thickness are significantly larger than those of the 18650. 18650 batteries perform better in terms of heat dissipation when the battery is operating.

2. High cost effectiveness and sufficient supply

Sony introduced 18650 cells in 1990.

Tesla and Panasonic jointly launched 21700 cells in 2017.

While the market expansion for 21700 cells has only been five years, that of 18650 cells has been ongoing for 20 years.

Less than 10 manufacturers produce 21700 cells, but there are more than 50 producers of 18650 cells on the market.

Additionally, it explains why there has always been a plentiful supply of 18650 batteries available for reasonable pricing.

How many types of 18650 cells are there?

The typical application of 18650 cells

Electric car

Electric bicycle

Emergency power light

Consumer electronics products

Power tools

l 18650 vs 21700 which one is better?

n 18650 vs 21700 battery: similarities

 The majority of the two batteries are lithium-ion batteries. Another commonality between 18650 and 21700 batteries is that they can be recharged and used in devices that require voltages of between 3.2 and 3.7 volts, depending on whether the power source is lithium iron or lithium ternary phosphate.

n 18650 vs 21700 battery: differences

We find differences from a few perspectives:

18650 versus 21700 batteries

We often get asked questions about the differences between the most common battery types. Hence this topic! To give more information about this matter. In this topic we will talk about the main differences between the two most popular battery types for flashlights. The 18650 and the 21700 batteries. As such you can easily decide which battery type will suit you best after reading this topic.

Difference in capacity

The primary distinction between 21700 and 18650 batteries is their size. Because the 21700 battery is larger than the 18650 battery, it has more capacity. One 18650 battery has a maximum capacity of roughly 3500 mAh, however a 21700 battery can deliver up to 5000 mAh. Of course, more capacity implies more burning hours. As a result, the 21700 is ideal for long-term use if you are unable to charge your battery in between. Consider a police officer who is required to handle traffic all night. When utilizing an 18650 battery, you must pay attention to the brightness of your light depending on the type of light you use.

Difference in power disparity

In addition to the difference in capacity the larger size of the 21700 is also an advantage. Because it is larger there is more room to reinforce the cooling and power characteristics of the battery. 21700 batteries namely have a capacity of up to 1400 watts. The 18650 stops at 800 watts. The difference in capacity ensures that the devices that use a 21700 battery have more power. A flashlight with a 21700 battery will therefore burn longer and brighter than a flashlight with a 18650 battery.

Example of the difference in power and capacity

Below a good example of the difference between the two types of batteries. We put this to the test with the Fenix HT18 hunting flashlight, 1500 lumens. We used this flashlight because it easily supports both type of batteries with the help of an insert.

Light modes for the Fenix HT18 with a 21700 Li-Ion battery

Turbo: 1500 lumens, burn time of approx. 1:40 hours*

High: 500 lumens, burn time of approx. 4:15 hours

Medium: 150 lumens, burn time of approx. 20:15 hours

Low: 30 lumens, burn time of 61 hours

Stroboscope: 1500 lumens

Light modes for the Fenix HT18 with an 18650 Li-Ion battery

Turbo: 1100 lumens, burn time of approx. 1:40 hours*

High: 500 lumens, burn time of approx. 2:15 hours

Medium: 150 lumens, burn time of approx. 14:10 hours

Low: 30 lumens, burn time of approx. 53 hours

Stroboscope: 1100 lumens

*The burn time of the highest light mode is calculated at the moment the lamp is switched on in the highest mode. After 2-3 minutes, the light automatically switches to a lower mode due to the temperature regulation.

Which one is better for your application? 21700 or 18650 battery?

After the above comprehensive comparison, I believe that you already knows the advantages/disadvantages of 18650 and 21700 batteries.

For small batch customers, because the number of 18650 manufacturers on the market far exceeds 21700 manufacturers, in order to facilitate more manufacturers to try, Ofcourse, 18650 is the first choice.

If high energy density and compact design space are required, we recommend the 21700.

For your battery design, do you have enough battery space? Under the same battery capacity, what is the cost difference between 18650 design and 21700 design? Welcome to leave a message below, or directly consult the ELB team to obtain quotations and solutions.

Conclusion

If you are looking for a good rechargeable battery for your flashlight we have got you covered. Whether you go with the larger 21700 or the smaller 18650 battery. We have a wide selection of both of them. Find the right battery on our battery page.

Frequently Asked Questions

Are 21700 batteries better than 1 8650?

21700 batteries have a higher energy density than 18650. The 18650 is one of the most popular types of rechargeable lithium-ion batteries, 18650 has a capacity of 2600- 3500mAH while the 21700 can reach up to 5000mAH, which means 21700 cylindrical li-ion cells have more energy density, which can result in more runtime.

What is the difference between 2N3904 and 2N3906?

Since the 2N3904 is an NPN transistor and the 2N3906 is a PNP transistor, this is the fundamental distinction between the two.

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