The short answer: Every hoverboard is unsafe, according to the US government. For now, at least.
2015 was the year that hoverboards really blew up, metaphorically and literally. Each week, a new celebrity seemed to be trying one out, while reports of hoverboards bursting into flames also appeared regularly. As Quartz has reported, many of the issues surrounding the safety of hoverboards revolve around how and where they were built. Up until this month, there was no standard for testing hoverboards. As a result, companies like Amazon have pulled hoverboards from their sites, and transport agencies like New York’s Subway have banned boards on its trains.
But now, with the backing of the government, Underwriters Laboratories (UL), an independent safety testing company, has created a set of tests to check whether hoverboards have been built safely. When a board passes all those tests, Washington will allow it to go on sale in the US—but so far, none have passed.
UL showed Quartz what it tests for:
Shoddy batteries that haven’t been properly tested are one of the main reasons hoverboards keep exploding. UL’s chemical engineers showed Quartz lithium batteries found in hoverboards from some of the biggest makers, which they locked into concrete-lined rooms with steel doors, for the two tests to come.
One UL test simulates what happens if a battery cell heats up. The second simulates a battery getting punctured—for example, if a hoverboard rolls over an especially rough surface. In both tests, the cells exploded with real force, and burned for a long time. When hoverboards cause household fires, says UL, black marks often found on walls and floors are likely from exploding battery cells.
Most of the hoverboards UL tested had an array of 24 battery cells, meaning the tests conducted in its concrete rooms were about 24 times smaller than the potential explosion from an entire hoverboard exploding. Most of the battery cells were shrink-wrapped in plastic, meaning they didn’t have much protection from sparks and punctures.
It’s nearly impossible for a consumer to check if the batteries in their hoverboard are safe, short of taking the entire board apart and testing the chemical makeup of their batteries. But when manufacturers start shipping UL-certified hoverboards, you should be safe to assume that any battery in a product bearing the UL logo is safe to use.
Some hoverboard manufacturers have started advertising that their boards’ batteries are UL certified. While that may well be true, the US government has said that until a company’s entire hoverboard has been inspected and certified by UL, it will not be deemed safe for sale in the US.
Inefficient charging can lead to overheating, which can lead to exploding batteries.
Most hoverboards use a USB charger, and UL recommends only using the charger that came with the hoverboard. The agency also suggests reading the label on the charger to check if something is amiss: One of the hoverboards on display in the lab included a charger with multiple spelling errors on its label, as well as a fake UL seal:
If this much care was taken on the label, how much care was taken with what’s inside?
UL opened up a few hoverboards to show that even when a battery is fine, faulty wiring could still cause a spark. One hoverboard in the demonstration had wires that had been crimped and exposed at some point during the manufacturing process. This could short-circuit the board, potentially tossing a rider off, or sparking an explosion, UL said.
Other boards had wires that were spot soldered to the batteries and other components, meaning that enough jiggling could eventually knock them loose. Before going for a ride, give your hoverboard a good shake to make sure nothing’s rattling around.
Quick manufacturing often means cutting corners. UL found instances where metal shavings had been left inside hoverboards, sometimes grinding around the metal joint that connects the two halves of a board. Loose filings could also short-circuit a board, causing battery cells to catch fire. Rough edges of metal could also cause a wire to tear.
UL found instances where some overboard parts were glued into place, even when they were well-secured by nuts and bolts. The agency said it wasn’t sure why the glue was there, in the first place.
The lab also tested boards to see how they held up when they were dropped. In the test that Quartz witnessed, the board tested cracked after one drop. A second drop exposed wires and broke plastic parts, which would make the board dangerous to ride.
UL hasn’t certified a single hoverboard yet. However, it is working with manufacturers around the world to help them meet their new standard. When a board is UL certified, it’ll have a holographic logo on the box that you should look for. But beware: Many knock-off boards are already putting fake UL logos on their products.
If you’re planning on buying a hoverboard, it’s probably worth holding off until you’re sure it has been tested and approved by UL. Now that these standards are in place, and manufacturers can start building boards that can be sold in the US again, a big question still remains: Is this too little, too late for the faddish technology?