Why an Electric Skateboard Shuts Off While Traveling Downhill

I picked up my electric skateboard and headed out of my house on top of a hill. With a fully charged battery, new shiny red helmet and cool Southern California breeze, I looked forward to a nice ride around the neighborhood. The brushless DC motor hummed loudly on the quiet street as I throttled the remote control to slow the electric board while the hub motor regenerated electricity to charge the batteries. With a path clear of any obstacles – I began to carve downhill maneuvering across the entire street. All of a sudden, my remote lost control of the board and it quickly began to gain speed. I had a split second  to jump off the skateboard before the steep slope caused the board to rapidly plummet downhill. The board then careened into my neighbor’s bushes on the side of the road.

I picked up the skateboard to investigate the cause of this fiasco while completely ignoring the damage inflicted upon the poor plant. It was immediately apparent that the Electronic Speed Controller had switched off since the LED indicator was no longer illuminated. I figured that I had hit a bump in the road which may have caused the switch to toggle from On to Off. Without a second thought, I turned the controller back on and continued my ride downhill. I had travelled less than 10 feet when the remote lost control of the skateboard for a second time. Luckily, I had not gained enough velocity and was able to quickly exit the board without much fanfare. Again the LED indicator was off! I chalked it up to poor workmanship and decided to walk the rest of the way down the hill. Once I reached a flat section of the street, I jumped back onto my board, pushed it a few feet and the motor roared back to life. The rest of the ride, both up and down hill, was uneventful and the electric skateboard performed flawlessly.

It was not until I arrived back home that I realized the battery IC was the primary suspect in my narrow escape when trying to force me to set a downhill skateboard speed record. Electric skateboards utilize lithium ion battery packs to power the motor, and employ regenerative braking to extend battery life. When the brake is applied, the motor is able to convert kinetic energy into electricity which pushes electrons into each battery. Funny thing about Lithium Ion batteries, once they are fully charged, any additional applied voltage may result in a fire or explosion. It is the job of a battery IC to prevent this overcharge by shutting off the speed controller to prevent over voltage. Lesson learned. Because I always start with fully charged batteries, I now ride uphill a bit before going downhill to prevent the battery IC from injuring me.