The Pros and Cons of Building a 21700 Battery Pack for Your Next Project

The Pros and Cons of Building a 21700 Battery Pack for Your Next Project

Are you thinking of building a battery pack for your next project? If so, have you considered using the 21700 battery? This powerful lithium-ion cell has become increasingly popular in recent years due to its high energy density and long-lasting performance. However, as with any technology, there are both pros and cons to building a 21700 battery pack. In this blog post, we’ll explore the benefits and drawbacks of using this type of battery for your project and provide tips on how to build one if you decide it’s the right choice for you. So sit back, grab a cup of coffee (or tea!), and let’s dive into the world of 21700 batteries!

What is a 21700 Battery Pack?

A 21700 battery pack is a type of rechargeable lithium-ion battery that has a diameter of 21mm and length of 70mm. It was developed to address the increasing demand for high-capacity batteries in electronics, electric vehicles, power tools, and other applications.

Compared to its predecessor, the popular 18650 battery, the 21700 offers several advantages. First, it has a higher energy density which means it can store more energy in a smaller size. This makes it ideal for devices that require long-lasting performance without being bulky or heavy.

Another advantage is its ability to handle higher discharge rates without overheating or degrading quickly. This means it can deliver more power when needed without compromising on safety or longevity.

Moreover, many manufacturers are now producing cells with improved durability and reliability thanks to advancements in electrode design and manufacturing processes. These improvements have made the 21700 battery an attractive option for those looking for reliable power sources that last longer than traditional batteries.

While there are some drawbacks to using this type of battery pack such as cost and limited availability compared to other types like AA batteries; if you’re looking for high-capacity performance in a compact form factor then a 21700 may be worth considering!

The Pros of Building a 21700 Battery Pack

Building a 21700 battery pack for your next project has numerous advantages. Firstly, this type of battery is known for its high energy density, providing more power than other battery types in the same size and weight range. This means that you can achieve longer-lasting performance with fewer cells.

Moreover, 21700 batteries have a higher voltage output compared to their counterparts. With a nominal voltage of around 3.6 volts per cell, they offer better efficiency and reliability when powering high-drain devices or applications.

Another benefit of building a 21700 battery pack is that it allows you to customize the capacity based on your specific needs. By choosing the appropriate number of cells and configuration, you can create a bespoke power source that meets your requirements without wasting space or resources.

Furthermore, these batteries are designed to handle higher currents without overheating or degrading quickly. This makes them ideal for use in demanding applications such as electric vehicles or grid storage systems where safety and longevity are paramount.

Since most modern devices now use lithium-ion technology powered by 18650 or similar-sized batteries; upgrading to 21700 packs offers an easy way to enhance performance while maintaining compatibility with older technologies.

The Cons of Building a 21700 Battery Pack

While there are numerous advantages to building a 21700 battery pack, there are also some downsides that must be considered. One of the biggest cons is the cost involved in creating one. The batteries themselves can be expensive, and additional components such as a battery management system (BMS) and charger will add to the total cost.

Another disadvantage is the potential safety risks associated with building your own battery pack. If not constructed properly, lithium-ion batteries can overheat or even explode, causing serious injury or damage to property. It’s crucial to have proper knowledge and experience when working with these types of batteries.

Additionally, building a custom battery pack requires significant time and effort. From researching which components to use, sourcing materials and assembling everything correctly takes considerable effort. Not everyone has the skills or patience required for this kind of project.

It may not always be practical or necessary for certain projects to use a 21700 battery pack due to its size and weight compared to other options available on the market.

While there are certainly benefits to building your own 21700 battery pack, there are also important drawbacks that need consideration before undertaking this type of project.

How to Build a 21700 Battery Pack

Building a 21700 battery pack may seem daunting, but it’s actually quite straightforward. To get started, you’ll need to gather the necessary materials: 21700 batteries, nickel strips, a spot welder, and battery management system (BMS).

Firstly, determine how many batteries you’ll need for your project. Then, connect them in parallel or series depending on the voltage and capacity requirements of your device. Be sure to use insulated nickel strips to connect the batteries securely without causing any short circuits.

Once you’ve connected the batteries together using nickel strips, use a spot welder to fuse them together securely. This will ensure that they remain in place and don’t come loose during operation.

Install a BMS to monitor the health of your battery pack and protect against overcharging or discharging. Make sure that everything is wired correctly before sealing up your battery pack with heat shrink tubing or electrical tape.

By following these steps carefully and paying attention to detail throughout the process, you can build a reliable and safe 21700 battery pack for all kinds of projects – from electric bikes and power tools to portable devices like laptops or smartphones!


Building a 21700 battery pack for your next project can be a great option if you need high-capacity batteries that are also durable and long-lasting. The pros of using these batteries include longer run times, improved power output, and increased safety features.

However, it’s important to consider the cons as well such as the upfront cost and complexity of building a custom battery pack. Additionally, it is crucial to follow proper safety protocols during construction and use.

With careful consideration and attention to detail, building a 21700 battery pack can provide numerous benefits for your project needs.