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‘Flame On’ for the Holiday’s Hottest Gift
Posted on January 11th, 2016 by Ken Klapproth in Chemical Manufacturing Excellence
Feeling burned by this holiday’s hottest gift? What was supposed to fuel this seasons tech innovation craze ends up sparking fires for hundreds of unsuspecting purchasers around the globe. While several potential reasons could be at play causing hoverboards to burst into flames, thermal runaway in the vehicle’s lithium ion batteries is evidently the source.
It seems the electronics industry is all too happy to oblige consumers every holiday season with a ‘must have’ tech gadget. 2015 was no exception with self-balancing electric scooters – more commonly known as “2 wheel hoverboards” – emerging as a ‘fan fav’. While the technology has been around for some time being used in the Segway and self-balancing unicycle, the cost of these modes of personal transportation has made purchase prohibitive to average consumers. Where there was demand and a prototype, enterprising manufacturers stepped in offering the hoverboards as low as $250.
Like any other technophile, I’m all for innovation – especially at a bargain – but it seemed like these devices sprung onto the market overnight, being picked up by nearly every retailer with spare floor space. I even saw a pile of them in a local pharmacy. But as an engineer, suspicions of compromises in quality arose as announcements of spontaneous fires began to emerge – in some cases even resulting in house fires.
So, what’s the cause? While there can be many reasons, the root of the problem appears to be in the Li-ion battery pack and a phenomenon known as thermal runaway. While lithium ion battteries are common today in most of our electronic devices, the power required to drive the hoverboards necessitates higher voltages making them more sensitive to material or manufacturing defects. Cells within the battery are separated by electric insulators of polypropylene or polyethylene. Material defects or inconsistent formulations could allow a short circuit between the high voltage cells leading to thermal runaway. Researchers at University College London put together a brief video explaining the phenomenon.
For a more in depth look and to see when and how thermal runaway occurs as viewed by thermal imaging, head on over to Grin Technologies YouTube Channel. You’ll see hot spots in the cells starting at about 0:30 in the time line and things really get interesting at about 1:50 in the time line even after the current stops flowing. Stick around past 2:30 to see the runaway jump from cell to cell.
While the jury is still out on whether the cause of these fires is the “what” of the battery materials or the “how” of the manufacturing and quality assurance processes used, it is clear that consumers have become wary of certain brands and lawyers have smelled blood in the water. One thing is clear – as engineers, it’s incumbent upon our profession to not only understand how a product might be used, but also how it could potentially fail. Researching and examining failure modes is what empowers uncommon knowledge to safely serve consumers and society.
Have any examples of unforeseen circumstances in your engineering work that come to mind? More importantly, how did you solve them? Share your thoughts in the comments section below and don’t forget to follow us on your favorite social media channel.
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