Regulations for lithium batteries
From laptops and cellphones to electric vehicles and battery banks, lithium batteries power the world. Lithium chemistries provide high energy densities, long lifespans, and flat discharge curves, making them an ideal choice for many products or applications.
However, lithium batteries can be dangerous and prone to thermal failure. Everyone knows about the troubles of the Galaxy Note 7 and its lithium battery, including when one caught fire on a plane. Consider also the deadly 2010 crash of UPS Flight 6 near Dubai. This was associated with a fire that auto-ignited in the cargo hold where significant numbers of lithium-ion batteries were being transported.
All batteries have the potential to cause harm, so all batteries are regulated under various safety standards. Because of their unique properties, lithium batteries are subject to stricter and more specific regulations than other kinds of chemistries. Foremost among these is UN/DOT 38.3, which regulates the transport of lithium batteries by sea, in the air, and over land.
If you don’t meet the standards of UN/DOT 38.3, you can’t ship lithium chemistries by plane, train, boat, or road—anywhere on earth.
Because UN/DOT 38.3 is so fundamental for commercializing lithium batteries, we’re diving in to its details in a two-part series. In this article, we’ll explain the finer administrative details, including:
- What UN/DOT 38.3 is
- What chemistries it applies to
- Whether it applies to cells, or only batteries
- When you have to retest an approved design
In part 2, we’ll look at the tests themselves, including how to pass (or fail) and how many battery samples are needed.
Let Aved be your partner in battery power. Contact our team today to discuss how our team can ensure regulatory compliance through effective design. Also ask us how we coordinate testing with our partners at Intertek.
What is UN/DOT 38.3?
“UN/DOT 38.3” refers to section 38.3 of the United Nations standard entitled Recommendation on the Transport of Dangerous Goods. Section 38.3 requires manufacturers of batteries to prove that their batteries won’t create dangerous conditions during shipping. The document, which undergoes regular revisions, is in its 7th edition as of 2019, and will have an update effective January 2022.
The “DOT” in UN/DOT 38.3 refers to the fact that the United States Department of Transportation (DOT) has adopted and enforces the standard. UN 38.3 carries force of federal law per the US Code of Federal Regulations 49§173.185. The US currently enforces the 6th edition, but compliance with the 7th edition ensures compliance with the 6th. Batteries tested to the 3rd edition, amendment 1 or any other newer revision are still considered compliant. In this article, we’ll reference the 7th edition.
But the US isn’t the only country that has adopted UN 38.3; this document is enforced all over the world. Anywhere you want to transport a lithium battery, you’ll have to meet the testing criteria of UN 38.3, hands down.
As mentioned, UN/DOT 38.3 is all about testing. To ensure the safety of batteries for shipping, manufacturers must submit samples of their batteries for testing. Batteries are subjected to abuse conditions and monitored for failure during 8 tests. These tests are:
- The altitude test
- The thermal test
- The shock test
- The vibration test
- The external short circuit test
- The impact/crush test
- The overcharge test
- The forced discharge test
We’ll discuss the technical details of these tests in part 2 of this series.
What chemistries are covered by UN/DOT 38.3? Is lithium polymer included?
Section 38.3 of the UN’s Recommendations is called “Lithium metal and lithium-ion batteries.” But, as Power Electronics explains, there are many different lithium-based chemistries. There’s lithium metal, lithium polymer, lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate, lithium nickel manganese cobalt oxide, lithium nickel cobalt aluminum oxide, and lithium titanate. The list will expand as scientists and engineers develop new ways to store energy.
But UN/DOT 38.3 does not distinguish among this vast variety. As far as international regulators are concerned, there are only lithium-metal, which has a metallic lithium anode, and lithium-ion, which has a lithium salt (this include lithium polymer). Both are subject to testing. Unless the UN decides to regulate different chemistries in some other way, UN/DOT 38.3 applies to lithium-anything.
Does UN/DOT 38.3 apply to cells, or just batteries?
Does UN/DOT 38.3 apply to cells and modules, or just batteries? The simple answer is that batteries, cells, and cells that make up batteries all must be tested.
The more complicated answer is that cells may have to undergo fewer tests than batteries—depending on how they will be transported.
To understand how UN/DOT 38.3 decides to test different types of devices, you have to understand that the standard only cares about safety in shipping. End use has nothing to do with it. Let’s dig into:
- Batteries versus cells
- Shipping individually, or as a component
- Decision-making when classifying batteries and cells
The answers to these questions determine what tests a particular device must undergo. Let’s look more closely.
Cells versus batteries
Cell, module, battery pack, battery assembly, power bank—there are lots of words to describe how batteries are assembled. But UN/DOT 38.3 only uses two: cell or battery. Here’s how it defines these terms:
From the 7th edition of Recommendations on the Transport of Dangerous Goods
Cell means a single encased electrochemical unit (one positive and one negative electrode) which exhibits a voltage differential across its two terminals, and may contain protective devices.
Battery means two or more cells or batteries which are electrically connected together and fitted with devices necessary for use, for example, case, terminals, markings or protective devices.
There are two distinctions to make here. First, cells have only one electrochemical unit, while batteries have at least two. In other words, batteries are bigger. A 2-cell module is a “battery” under the standard, even if it can’t be used as a battery.
Second, cells might have protective devices, but batteries are fitted with devices necessary for use. In other words, we assume batteries have more safety features than cells.
Will a cell ship individually? Or as part of a finished battery?
But UN/DOT 38.3 doesn’t just distinguish between cells and batteries. It also asks whether devices will be transported separately. As Rich Byczec from Intertek explains, the answer to this question determines if a cell can be treated as a cell, or if it must be treated as a battery.
Because cells are often components of larger batteries, and because batteries typically have more safety features than cells, UN/DOT 38.3 specifies fewer tests for cells. But this is only if the cells won’t be shipped on their own. The safety features of a battery do nothing to protect the component cells if they are shipped unassembled. A cell that ships individually must be tested as a battery.
Check out this table to determine what tests are required for different types of batteries and cells:
Decision-making when classifying batteries and cells
UN/DOT 38.3 actually gives manufactures some flexibility in how they classify and test their batteries. But this flexibility requires some economic decision-making.
First, manufacturers can choose to ship cells only as part of complete batteries. This choice saves money up-front on testing fees and testing samples—but there’s an opportunity cost. This choice takes away the option to ship cells or modules as replacement parts, for recycling, or if manufacturing situations change.
Second, manufacturers have some flexibility in how they define “battery.” UN/DOT 38.3 says:
From the 7th edition of Recommendations on the Transport of Dangerous Goods
A cell or battery that is an integral part of the equipment it is intended to power that is transported only when installed in the equipment, may be tested in accordance with the applicable tests when installed in the equipment.
In this case, an “integral” battery is not just very important, but integrated. The battery and equipment are a complete unit, not two separate components. If the two will never ship separately, the assembled equipment, with whatever protective circuitry and devices it might have, can be tested as the “battery.
The example Rich Byczec at Intertek gives for this is a laptop with a battery installed by welding. Such a laptop, which often has battery management and thermal management, is the “battery” because it can’t be shipped without the battery.
Testing can be expensive, so choosing whether or not to test a component separately is an important economic decision. If you choose not to certify a cell for individual shipping, you can save money. But you also limit your options for the future. Stay tuned for a future article on the economics of testing and certification.
When do I have to retest under UN/DOT 38.3?
If a battery is certified to UN/DOT 38.3, does it need to be retested if you want to make minor adjustments? For original equipment manufacturers, it often makes sense to reuse battery designs. There’s no reason to design an entirely new battery when you have an existing design that only needs some tweaks. That way, you save money on the design phase and manufacturing process.
It depends. Section 126.96.36.199 of Recommendations lists all the changes to a battery design that require retesting. These include (but are not limited to):
- For primary devices, a change of 0.1 g or 20% by mass, whichever is greater, of the cathode, anode, or electrolyte
- For rechargeable devices, a change in the nominal watt-hours of more than 20%, or an increase of nominal voltage of more than 20%
- A change in the material of the anode, cathode, separator, or electrolyte
- A change in any protective devices, hardware or software
- A change in the safety design
- A change in the number or connecting mode of component cells
Ultimately, the big question is: could this change impact test results? If it could, you need to retest.
Also remember that the definition of “battery” is somewhat flexible in UN/DOT 38.3. If you test one assembled, battery-powered widget as a “battery,” you might have to test each new widget design as a new battery.
Compliance with UN/DOT 38.3 lithium battery regulations
Compliance is complicated. Fortunately, you don’t need to figure out everything for yourself. Trust the design team at Aved to provide you with lithium batteries that meet your OEM needs and comply with regulations like UN/DOT 38.3. Along with our testing partners at Intertek, we will guide you through the regulatory process to bring your devices to market.
Because of their high energy density and long lifespans, lithium chemistries are increasingly popular for all kinds of battery applications. But their thermal properties create some inherent risks, which are mitigated by international regulation.
To ensure safety during shipping, the United Nations recommends that lithium batteries be tested according to a standard known as UN/DOT 38.3. This standard, enforced by the United States and nearly every other jurisdiction in the world, requires lithium batteries to undergo extensive safety testing before they can be shipped by plane, train, boat, or truck.
In this article, we’ve gone over the administrative details of UN/DOT 38.3. In Part 2, we’ll look at the process of safety testing, including how to pass (or fail) the tests.
Your partner in every stage of the battery design process, Aved designs and manufacturers batteries to meet your application needs and comply with global regulations. Contact our team to discuss your next project or request a quote.