21700 vs 18650 Battery: Which One Is Better?

The launch of lithium batteries has promoted many industries, such as the manufacturing of cordless tools in the construction and decoration industry, a large number of applications in the energy storage industry, and product innovation in electric vehicles, drones, electric scooters, etc.

21700 vs 18650 battery: Some Tesla models use 21700 batteries instead of 18650 batteries. Various industries often discuss the differences between 21700 and 18650 lithium batteries. When faced with choosing which battery type to use, this article can help you understand which battery is better for your application.

21700 vs 18650 batteries: What is the difference?

Dimension

The sizes of 18650 and 21700 battery are different. The named numbers also represent the size, usually referring to the diameter and length.

• Dimensions of 18650 battery: diameter, 18mm, length, 65mm
• Dimensions of 21700 battery: diameter, 21mm, length, 70mm

Capacity

From a single battery perspective, the working performance of the battery varies depending on its size. The diameter and length of 21700 battery are larger than that of 18650 battery, so the volume is larger. This means that the 21700 battery has larger capacity and longer running time:

• The rated capacity of 18650 battery is generally 2200mAh ~ 3600mAh (2.2Ah ~ 3.6Ah);
• The rated capacity of 21700 batteries is generally 3000mAh ~ 5500mAh (4Ah ~ 5.5Ah).

Energy Density

The 21700 battery has higher energy density. 18650 battery has a lower energy density.

Weight

There may be a slight deviation due to different specifications. Overall, the 18650 battery weighs about 48g, and the 21700 battery weighs about 60g.

Price

Producing a 21700 battery uses more raw materials than a 18650 battery, so generally, 21700 batteries are more expensive.

Internal Resistance

The 21700 battery has a multi-pole design and has lower internal resistance than the 18650 battery.

Similarities between 21700 and 18650 batteries

Both 21700 and 18650 batteries are excellent batteries, and they are used in Tesla electric cars. They have several things in common:

• Cell materials are similar (such as lithium iron phosphate, and ternary lithium)
• They are all cylindrical cells
• All have similar self-discharge rates
• They are all deep-cycle batteries with a cycle life of up to 3,000 times and 80% DoD.
• 21700 and 18650 batteries have the same voltage, both are 3.7v. There is no compatibility issue at this point.
• The same temperature range (-20℃ to +50℃, optimal temperature 25℃) can be used in different climates and temperatures.
• Both have relatively high discharge rates, which can support high levels of power.

Read more:

• 14500 battery vs 18650 battery: Comparison Analysis
• 18650 vs AA Battery: What’s the Difference?
• Lithium vs Alkaline Batteries: Comparison Analysis

Advantages of 21700 batteries

Compared with 18650 batteries, from the perspective of the advantages of single 21700 batteries:

• More capacity storage space
• Battery internal resistance is usually relatively low
• Support higher current
• Higher power

When talking about the most popular battery, we have to mention Tesla’s battery. Tesla pioneered the 21700 battery. The 21700 battery in Tesla Model 3 and Tesla Model Y has a capacity of 5000mAh and supports 15A continuous current. There are 4,416 batteries of 21700 types in each electric vehicle.

21700 vs 18650: According to the information disclosed by Tesla, they use 21700 batteries to replace 18650 batteries. From the perspective of the entire battery system, the advantages of 21700 batteries are more obvious.

Reduced cost per kWh

Judging from the selling price of Tesla’s battery system, the 21700 lithium battery is US$170/kWh, while the 18650 lithium battery system is US$185/kWh. The cost per kWh is reduced, and the battery system cost drops by 9%. The battery pack is also simplified. The 21700 battery pack requires fewer connecting wires than the 18650 battery with the same capacity.

Increased energy density

From the perspective of energy density, the 21700 lithium battery system is 300Wh/kg, while the 18650 lithium battery system is 250Wh/kg. The energy density of the battery is increased by 20%.

Advantages of 18650 battery

Since Sony first launched the 18650 lithium battery in 1991, this model has achieved great success and is widely used in various fields: consumer electronics and electric vehicles are the most important markets, such as notebook computers, electric bicycles, electric vehicles, etc.

Tesla’s early Model S, X and 3 Series electric vehicles used 18650 batteries provided by Panasonic from Japan. In recent years, in order to improve the energy density of battery packs and reduce the number of batteries in the battery pack. Panasonic has launched a 21700 model lithium-ion battery with a larger capacity which is used in the latest Model 3 model.

More compact and lighter

The shortcomings of 18650 are actually its advantages. It is more compact. When space is limited, it needs to be connected in series to reach a specific voltage. 18650 is smaller in size, and 18650 battery packs can be used in compact spaces. If it is just a small flashlight or portable electronic product, 18650 is more than enough.

Easier to dissipate heat

Since the diameter, thickness and battery length of the 18650 battery are lower than that of the 21700 battery, the lower volume 18650 battery is easier to dissipate heat.

The price is advantageous and the market is wide

18650 battery type has been on the market for a long time and it is easy to find suppliers. There are more manufacturers of 18650 batteries than 21700 batteries, which can ensure the supply.

How to choose the right lithium battery for your applications?

Main applications of 21700 battery

If your application requires long-term use and sufficient electricity and power to maintain, then the 21700 battery is the best choice. For example, security personnel need to patrol for a long time at night, and flashlights need to be illuminated for a long time at night.

Vehicles with sufficient power and long endurance are needed. For example:

• power tools
• small household appliances
• mobile power supplies
• outdoor power supplies
• two-wheeled electric vehicles
• new energy vehicles, etc.

NPP 21700 batteries recommend: NPP 21700 5000mAh battery

Main Applications of 18650 Batteries

For situations where space requirements are high and compact and lightweight, it is recommended to use 18650 batteries:

• Electric tools: such as electric scissors, electric drills, electric hammers, etc.
• Consumer electronic products: such as laptops, tablets, smartphones, handheld game consoles, etc.
• Electric transportation tools: such as electric bicycles, electric motorcycles, electric cars, etc.
• Intelligent equipment: solar street lights, door locks, smoke detectors, wireless monitoring, etc.
• Toys and models: such as remote-controlled cars, remote-controlled airplanes, robots, etc.
• Medical equipment: such as portable blood pressure meters, blood glucose meters, heart rate meters, etc.
• Military equipment: such as night vision devices, laser sights, etc.
• Industrial equipment: such as drones, robots, etc.

NPP 18650 batteries recommend:

• NPP 18650 2200mAh battery
• NPP 18650 3000mAh battery
• NPP 18650 2600mAh battery
• NPP 18650 6800mAh Battery

18650 vs 21700: For small devices batteries questions

Is 21700 battery suitable for 18650 devices?

When the battery types and the applications are the same, if there are no size requirements, 21700 batteries can replace 18650 batteries. The dimensions of 21700 batteries are larger than 18650 batteries, so 21700 batteries cannot be installed in 18650 devices. Replacing a 21700 battery with an 18650 battery requires an adapter sleeve, but doing so will result in a significant decrease in storage capacity.

Can the 18650 charger charge 21700?

Yes, the 18650 charger can be used on the 21700 battery, but the 21700 battery can support a larger charging current. It is recommended to use the specified charger.

Summarize

21700 vs 18650 battery: 21700 batteries have made significant progress in upgrading, and 18650 batteries still have a large application market.

As a professional lithium battery manufacturer, NPP can provide customized solutions for different battery pack systems, such as solar systems and home energy storage systems. Please feel free to contact us.