But what is actually causing all these fires? In the New York and Louisiana incidents, the board was plugged in and recharging. In the mall incident, the board wasn’t plugged in at all; there have also been reports of scooters bursting into flames while people were riding them. Plugged in or not, the big problem has to do with the quality of the rechargeable lithium-ion batteries inside these things. They’re almost always tucked in one of the foot rests, and they work the same way as the lithium-ion batteries in our smartphones, tablets, and laptops. They’re just a lot more prone to defects. Jay Whitacre, Professor of Materials Science & Engineering at Carnegie Mellon University, says that the problem doesn’t have to do with these self- balancing scooters themselves, but with the quality of the batteries being used. They’re cheap, and it makes sense: This is a hot (pun not intended) holiday product, the reputable models are pretty expensive, and more-affordable brands are using cheaper components to lure in shoppers that don’t want to spend a grand or more on a hands-free Segway. Predictably, a slew of cut-rate brands are flooding the market with shoddy scooters made from cheapo components. 3 4

“There are a lot of factories in China that now make Li-ion batteries, and the reality is that the quality and consistency of these batteries is typically not as good as what is found in top tier producers such as LG or Samsung,” Whitacre says. “These are known as ‘low cost li-ion batteries’ by most in the industry—they are not knockoffs or copies, but are instead just mass- manufactured cells.” With these cheap batteries, a lot of things can cause fires. For one, the nature of a scooterboard—it can bang into stuff, smash into things at high speeds, and be abused by bros—makes the batteries susceptible to damage. It’s not just the nature of a cheap battery, it’s the nature of any lithium-ion battery. 5 6

In a cheaper battery, Whitacre says the separator between each battery’s anode and cathode—which are what the current flows through—may not be aligned correctly. Image it like this: The cathode is at one end of the battery, the anode at the other, and the separator is (surprise!) between them; its job is to keep them apart so nothing short circuits. An issue, in the cheaper batteries, is there could be small holes in the separator thanks to impurities in metal particles that can puncture the anode/cathode separator. In either of those cases, the damage can cause a short circuit. This is not new at all: Lithium-ion batteries have long led to explosions—in smartphones, laptops, airplanes, cars…the list goes on. Lithium-ion batteries are great because they are small but hold a lot of energy, so electronics manufacturers are obviously going to use them. But packing all that power can come with its risks in some products—that risk specifically being fire. That’s why our high-powered, long-range electric cars, like those made by Tesla, have highly advanced cooling fans and heat-sink systems. The fan is the key component inside the vehicle that keeps the battery cells operating at a safe temperature. 7 8

“There is no way to tell when buying, since the catastrophic failure likely will not manifest until the battery is fully charged and discharged several times,” Whitacre explains. “This charging/discharging mechanically exercises the guts of the cell and typically provides the ultimate trigger for the failure.” If all of this hasn’t diffused (that pun was intended) your excitement for a board, then at the very least, you should know how to put out a fire—keep a fire extinguisher or bucket of water handy, friends. 9 10

So what can a consumer do if they really have their heart set on one of these bad boys? Conventional wisdom would say they should just stick with top tier brands, but this is where things get confusing, because this product category is totally new, and no exemplars of quality have emerged. A higher price should be an indicator of better quality, but companies such as IO Hawk and Hovertrax, which make more-expensive devices, aren’t exactly perennial tech powerhouses. This “hoverboard” trend is almost certainly a fad, and it’s hard to know whether any of these companies will be around at this time next year. Regardless of how much you’re paying, it’s almost impossible to tell what kind of fire hazard lurks (or doesn’t lurk) inside any scooter. The scariest part is that you may not find out until it’s far too late

First read Thinking codes

? - had a question about

* - important information

! - found interesting

Summary I n the article "Why Hoverboards Keep Exploding," the author...

Second read Language

What words does the author choose to emphasize and why?

What is the meaning of words or phrases in relation to the passage?

What is ironic about the scooters being called "hoverboards"?

How does the writer introduce the dangers of hoverboard fires?

What specifically is causing the hoverboard fires?

Take out your Hoverboard article and close read questions from yesterday.

Third read Syntax

What is the tone of the passage and how do you know?

How does the author show bias in the passage? If there is no bias, how does he show objectivity?

Where does the text leave matters uncertain?

What would Whitacre tell consumers to avoid when purchasing a hoverboard?

WHY HOVERBOARDS KEEP EXPLODING T IM MOYNIHAN DATE OF PUBLICATION: 7:00 AM

Fourth read Context

For whom and why did the author write this?

What is the general understanding or the big idea?

What were the possible influences or impact on the content or the world?

How might this article affect hoverboard sales in China?

THOSE SELF-BALANCING SCOOTERS that everyone’s calling “hoverboards” don’t actually hover. But that’s not the strangest thing about them—that would be the fact that this year’s most popular holiday gift keeps catching on fire. An exploding two-wheeler burned down a house in Louisiana a few weeks ago; another scooter combusted in the same state in the past week. A gyroboard caused significant damage to a home in New York a few days ago. At a mall in Washington this week, a scooterboard caught fire and shoppers were forced to evacuate. The perceived danger is significant enough that major airlines have banned the little vehicles altogether. 1 2