Custom lithium batteries bring with them a wide range of different benefits that cannot be ignored. In addition to being known for their light weight, they also offer the highest energy density among available options.
However, they are also considered to be "Dangerous Goods" by the United Nations. This is because these batteries might experience a phenomenon called “thermal runaway”, which is when any cell in the custom battery pack reaches a temperature that is higher than the battery's melting point.
When this occurs, it could cause a chain reaction that can easily impact all the other cells in the battery pack. If the battery doesn't simply leak or rupture, thus rendering it unusable, you could be looking at a fire or even an explosion. This is a big part of the reason why certification is so essential in this context.
According to one recent study, there were approximately 25,000 instances of fire or overheating in lithium-ion batteries over the last five years alone. In New York City, there were 10 deaths and 226 injuries reported between 2021 and 2022.
None of this means that these types of custom battery packs are inherently unsafe. It is not proof that fires in these batteries occur more often than they do with other types. It doesn't make them harder to store or even transport, nor does it negate the previously mentioned advantages. It just underlines the importance of guaranteeing compliance and certification moving forward. To get to that point, there are several important things you'll want to keep in mind.
Specific Battery Pack Design Criteria
In terms of compliance as it pertains to custom battery packs, the most important thing to concern yourself with is UN38.3 certification. Note that this is something that must be completed before the battery can be transported, and only lithium-based batteries are held to this process. It's not a concern for any other type of battery chemistry.
Lithium batteries and battery packs must be packaged and labeled in compliance with IATA regulations.
UN38.3 certification is accepted as both a national and international standard. Any battery pack manufacturer that is planning to ship a lithium-based battery as a pack, as an individual cell, or even already installed in a product, must follow it. Note that based on the broad nature of that description, this means that it applies to virtually everyone.
The purpose of UN38.3 certification ultimately means that your custom battery pack can pass not only electrical and mechanical safety requirements, but environmental ones as well.
To achieve UN38.3 certification, it will go through a series of tests that include:
- The primary and secondary cells and/or batteries will be exposed to a low-pressure simulation.
- Integrity testing will then be performed, where the custom batteries will be exposed to both extreme temperatures and rapid changes. This, too, occurs in both the primary and secondary cells and/or batteries.
- Vibration simulations will also be performed, attempting to mimic the type of conditions the battery might be exposed to during transportation.
- Similarly, shock and vibration testing will be conducted to make sure that the custom battery pack can stand up to the force of being transported, sometimes without as much care as you would expect.
- The custom battery pack will undergo an external short circuit simulation.
- It will then go through impact and crush testing.
- Rechargeable batteries in particular will go through overcharge simulations. Note that this test is targeting secondary batteries.
- Finally, a force discharge test will be conducted.
Given the precise nature of the testing and the potential volume of custom batteries that need to be tested, it is estimated that the entire process could take between four and six weeks to complete.
This is the type of certification that the battery designer will need to take care of. In fact, if the custom battery is redesigned in any way after the aforementioned testing has been completed, it will have to go through the process all over again to receive new testing.
It's also important to mention that the certification is only valid for a specific custom battery manufacturer. If you switch to a new manufacturer, even if the design of the battery remains fundamentally unchanged, the new manufacturer will need to go through the testing process to receive certification.
This is because a comprehensive report is generated at the end of the testing. That report includes, among other pieces of information, the names of all companies involved. If the manufacturer changes, a new report will need to be generated - thus there will be the need for new certification.
Additional Considerations About Battery Pack Compliance and Certifications
While on the subject of lithium-based custom batteries, note that you will also need to have IATA certification as well. This is a certification intended to make sure that everyone throughout the supply chain - from shippers to cargo handlers to airlines and everyone in between - can meet safety obligations in terms of these inherently sensitive batteries. It isn't the custom battery pack (or the product that contains it) that will need to get certified, however. Here, you're talking about certifying the employees who will be responsible for shipment. This is something they will have to do every year. Think of it as an extension of the benefits that UN38.3 certification has to offer in terms of peace of mind alone.
An independent testing laboratory will need to perform the actual testing and certification process of any custom battery packs that you're working with. TÜV SÜD America and the Southwest Research Institute are two examples of organizations that perform this type of testing, although there are many others.
Summary
More than anything else, this type of compliance and certification shows off that a manufacturer is committed to the safety of all those who take advantage of their custom battery packs. It's absolutely a factor that must be considered during the initial development process.
If you'd like to find out more information about ensuring compliance and certification for custom batteries, or if you're just eager to speak to someone about your organization's own needs in a bit more detail, please don't hesitate to contact Epec Engineered Technologies today.
