Why Hoverboard Batteries Exploded and Power Tools Do Not
I was recently a guest on the Pro Construction Guide podcast and talked about some of the cool new tools that have hit the market. One reader responded with a great question, essentially asking why hoverboard batteries exploded but power tools have not. I thought I’d include it here for our readers since it’s such a great question.
Question from PCG reader Duncan: Clint, I enjoyed the article on power tools and where they are likely to go in the future. It triggered a question about Lithium batteries and these hoverboards that continue to burn up. What is the difference between the batteries that are used in the boards and those used in tools? Obviously, there is now a lengthy track record of success in the use of these batteries in portable tools, and certainly no one I know babies their tools. The question remains—why are the results so different? Do you think it is the battery design or the design and execution of the wiring and connections surrounding the power sources? Might be a good article for next time. Thanks, Duncan.
Why Hoverboard Batteries Exploded
In speaking with the engineers at companies like Milwaukee and Bosch in the past on the subject of how lithium-ion batteries work, we learned quite a bit. Some of the issues surrounding batteries include what kind of cell and platform are used, but another really important consideration is what kind of electronics and protection are offered (and protection comes in electronic form as well as how the battery pack is physically designed).
With the hoverboard situation, what seems to have happened is that the individual cells, the pack, and/or the system are being allowed to exist with any of the following conditions present:
- The cells are simply overcharged, making them rather dangerous and volatile
- The cells are allowed to be recharged before they have sufficiently cooled down
- The individual cells are manufactured with sub-par components and quality control
- The cell packs are constructed with very little attention to heat dissipation and protection
- The charger for the battery pack is designed with very low-cost components and no ability to cool the pack before charging
These are also, depending on the model of course, 36V/4.4Ah or larger battery packs made up of as many as twenty 18650 cells (or similar as has been the case)—so there are a number of cells within that can either overheat, overcharge, and/or discharge at very high current. A lot of discussion has gone into the use of original Samsung cells (vs. cheaper knock-offs), but the problem of why hoverboard batteries exploded goes much deeper than that.
Some of these boards overloaded and/or caught fire while charging, others while being used (with the batteries discharging). Still others burst into flames while stored (after they had been used and/or charged). The reason this doesn’t happen more often with respect to power tools is that there’s a lot more quality control. You don’t have a ton of knock-off batteries and tools entering the US market—whereas everybody started knocking off both the batteries and the hoverboards themselves…and not many people were worried about brand loyalty or quality. Let’s face it, as consumers we just expect things to work, regardless of where they’re made…and we certainly don’t expect our pants to catch on fire while riding on a toy!
Manufacturers like Milwaukee, Ridgid, Makita, DeWalt, and others incorporate a lot of technology in their tools, batteries, battery pack circuitry, and the intelligent chargers themselves. All of this is designed to keep the battery pack from discharging too quickly, running hot, being overcharged, charging while too hot, or any other potential issues. And if you notice, not too many quality power tools come with “wall-wart” style chargers. Most actually serve to cool the battery before it charges.
In conclusion, the reason why hoverboard batteries exploded involves a little bit of everything you mentioned—the battery design, the electronics and connections, and the fact that tool companies have been doing this a while now and have proven track records on how to discharge 20 amps or more from a pack without blowing anybody up. Maybe we should all be just a little bit more impressed the next time we grab a battery pack!
Hope that helps—have a great week!