Battery Shipping Mistakes

If you've never Googled "Can I ship lithium batteries," you're either early or already in trouble.

Transportation is not a backend problem. It's a design constraint you ignored. The regulations governing lithium battery shipments are dense, unintuitive, and brutally unforgiving, especially when you discover them at the wrong moment. This guide ranks common shipping mistakes not by severity, but by when they typically surface: early enough to fix, late enough to hurt, or so late they kill timelines entirely.

This isn't arbitrary bureaucracy.

Lithium batteries are classified as Class 9 dangerous goods for good reason. Between 1991 and 2016, the FAA recorded 138 airport and air incidents involving lithium batteries: smoke, heat, and fire from devices like e-cigarettes, laptops, and mobile phones. Some incidents were caught before takeoff. Others required emergency landings when batteries ignited in cargo holds. 

Since 2016, bulk lithium battery shipments are restricted to cargo aircraft only and banned from passenger flights entirely. Since 2008, lithium batteries cannot be placed in checked baggage; they must be carried onboard where cabin crew can respond to fires. The reasoning is simple: a burning battery in the cabin can be fought. A burning battery in the cargo hold requires an emergency landing and a lot of luck.

The fire risk isn't theoretical. Thermal runaway: where a failing cell heats adjacent cells, triggering a chain reaction, can turn a small battery into an uncontrollable fire. "It worked in the lab" means nothing when the lab doesn't simulate a pressurized cargo hold at 35,000 feet.

Translation: If your shipment looks confusing, the answer from carriers, airlines, and freight forwarders is always no. They default to rejection because the downside of getting it wrong is catastrophic.

The most misunderstood checkbox in hardware.

All lithium batteries must pass UN 38.3 testing requirements before air transport. This suite of tests covers altitude simulation, thermal cycling, vibration, shock, external short circuit, impact, overcharge, and forced discharge. It's a rigorous safety gate and it's also wildly misunderstood.

What UN 38.3 covers: Verification that a lithium battery can survive typical transport stresses without fire, explosion, or rupture.

What UN 38.3 does not guarantee: That you can ship your battery anywhere, in any quantity, by any method. Passing UN 38.3 is admission to the maze, not the exit.

After UN 38.3 comes the real complexity: IATA Dangerous Goods Regulations (DGR), which specify exactly how, where, and in what quantities batteries can move. Then individual carriers add their own restrictions. Then countries add theirs. Your UN 38.3 certificate is necessary but nowhere near sufficient.

Exceptions exist for prototypes and testing purposes under CFR 49 173.185(e), but these are narrow and heavily documented. Don't assume your R&D samples qualify without checking.

Assuming Installed Batteries Don't Count

"It's inside the product" doesn't save you. Installed does not mean exempt. While batteries contained within devices like smartphones, laptops, and watches face fewer restrictions than spare batteries, they're still regulated. The distinction matters: a laptop battery installed in a laptop ships under different rules (PI 966/967) than the same battery shipped loose (PI 965).

The confusion intensifies with power tools and other devices with interchangeable battery packs. These don't count as "contained" batteries because the packs are designed for removal. Every removable battery pack is a spare battery in the eyes of regulators, regardless of whether it's currently installed.

Designing Packs That Land Just Over 100Wh

There's an invisible cliff at 100Wh. Below it, you're in Section II territory with simplified requirements. Above it, you're in Section IA: full Class 9 dangerous goods handling, mandatory training and certification, and a cascade of additional restrictions.

For passengers, the carry-on limit is 100Wh per battery, with allowance for two spare batteries up to 160Wh each. For commercial shipments, crossing 100Wh triggers a completely different regulatory framework. This is why 99Wh battery designs exist and aren't accidental- they're deliberate engineering choices to stay under the threshold.

To calculate: multiply rated capacity (Ah) by nominal voltage. A 3.3Ah 18650 cell at 3.6V is about 12Wh. String enough of them together, and you're over the line before anyone on the team realizes the shipping implications. One cell choice made in the lab can flip your entire shipping category.

Forgetting State-of-Charge Requirements

Batteries must be shipped at 30% state-of-charge. This isn't a suggestion—it's a requirement across Section II, Section IB, and Section IA shipments. The rule exists because lower SoC reduces thermal runaway risk during transport.

Teams discover this after cells are already built, tested, and packaged at 100% SoC. Now you need to discharge them- carefully, uniformly, and with documentation. This breaks testing schedules, adds process steps, and delays shipments. It's especially painful when you've built dozens of packs for pilot customers and none of them can legally ship.

“Ops will handle it” is the energy that kills product launches.

In early-stage hardware companies, shipping gets treated as a downstream logistics detail rather than a design constraint. Engineering locks the battery architecture. Business development promises delivery dates. Everyone assumes there’s an operations function ready to catch the handoff. In reality, that function often doesn’t exist yet or it’s one person inheriting an impossible box.

By the time someone asks, “How do we actually ship this?”, the design is frozen, the packs are built, and validation is complete. Now every fix is expensive. Staying under 100 Wh would require re-validation. Meeting 30% state-of-charge limits means adding discharge steps that don’t exist. Using a certified dangerous goods shipper means weeks of onboarding no one budgeted for.

None of this was in the timeline because no one owned shipping early enough.

Regulations don't scale linearly with product maturity. Early prototypes can often ship under testing exemptions. Small pilot batches fit Section II limits. But as you scale: larger packs, higher volumes, more destinations, the requirements compound rather than add.

You cross the 100Wh threshold and suddenly need Class 9 certification. You ship to a new country and discover different national requirements. You increase volume and your freight forwarder requires additional documentation they didn't need for smaller shipments. Each step up reveals new constraints that weren't visible at the previous scale.

The cost of redesigning after validation is brutal. Re-testing means time and money. Re-certifying means more time and more money. And if you've already promised delivery dates to customers, you're negotiating delays while scrambling to solve a problem you could have designed around from the start.

The fix isn't complicated, it's just early. Treat transportation as part of system architecture, not as a problem for the logistics team you haven't hired yet.

Design with shipping thresholds in mind. Know that 100Wh is a cliff before you choose your cell count. Know that 30% SoC shipping means your production process needs a discharge step. Know that Section II limits (8 cells at 20Wh, 2 packs at 100Wh, 2.5kg total) will constrain how you ship samples to early customers.

Ask the annoying questions before they become expensive ones: How does this product actually reach customers? What certifications do we need? Who on this team is responsible for understanding dangerous goods regulations? The earlier you ask, the cheaper the answers are to act on.

Regulations don't slow startups. Late decisions do. The shipping constraints on lithium batteries are real, consequential, and completely knowable in advance. Every threshold, every documentation requirement, every certification need is written down in regulations you can read today.

The teams that get bitten aren't the ones who face hard constraints. They're the ones who discover those constraints after the design is locked, the validation is complete, and the customer is waiting.

Ship early. Ask questions earlier. And remember: if your shipment looks confusing, the answer is always no.