This DIY installation may be the best explanation for regenerative braking we’ve seen – Jalopnik

Regeneration is a wild concept. Young minds often explode when they hear that an amazing starfish can grow new arms if one is snapped off; the details of why and how will come later. Likewise, many of us nod along when we’re told that regenerative braking systems help recharge batteries, then tilt our heads like a confused dog when asked how that happens. We know it, but do we know it? Jeremy Fielding is a talented YouTube creator with an infectious love for mechanical engineering, and a regenerative braking rock star. His DIY installation and explanation of the science behind the scenes may be the best we’ve ever seen.

Every electric and plug-in hybrid vehicle sold in the US has some sort of regenerative braking system. Ordinary braking systems use friction to stop a car, and the energy is converted into heat. Regenerative braking converts forward motion into energy to charge the batteries, which in turn can help extend range or control other systems such as the radio or air conditioning. It’s so magical that regenerative braking can even prevent your child from passing their driving test.

Fielding shows and tells how the magic happens, using an impressive regenerative braking setup of his own making. It features a DC speed controller and a treadmill-pulled motor, as well as a custom display box for speed and power, connected to a speed sensor. Using a homemade flywheel as a substitute for a car and light bulbs illustrating battery charging, science comes to life as Fielding flips a drum switch to demonstrate acceleration and regenerative braking in action.

Those who aren’t already among the 1.18 million subscribers to Fielding’s primary YouTube channel can be inspired by knowing that he’s a self-taught tinkerer who changed careers to pursue his passion. He says at JeremyFielding.com that his goal is to “attract people to mechanical engineering with great projects, inspire them with ideas and then teach them how to do it.” Whether your car has regenerative braking or not, his presentation here is well worth your time.

Fielding’s video makes it clear why slowing down without braking is a regenerative braking phenomenon: the accelerator pedal works like a toggle switch. By pressing the pedal, an electric motor becomes a power user, sucking juice directly from the battery. Releasing the pedal turns the motor into a power generator, powered by the force of the vehicle’s forward motion. The more the engine sucks that kinetic energy to charge the battery or power other utilities, the faster the vehicle slows down, like this Lucid Air Pure AWD that uses only regen braking when stopped at highway speeds.

Through a series of beautifully simple demonstrations – including the most strangely hypnotic sequence of a cylindrical magnet floating along the inside of a copper tube – Fielding distills Lenz’s law of energy opposition, and we learn about the properties of electromagnetism that ultimately determine why an electric car can’t recharge itself indefinitely. Fielding also discusses the pros and cons of how regenerative braking can save brake pads, which some Tesla owners have claimed can last 100,000 miles in their electric chariots.