Many people ask whether electric cars can charge up while driving along, which this video explores. The short answer is that self-charging road surfaces and physics-defying dynamos won’t really work, but integrated solar panels and improved regen braking will help… a bit.
This video explains the benefits and shortfalls of regen braking, and looks at whether a self-charging EV is genuinely likely.
The individual timestamps/sections of this video are:
- 0:00 Intro
- 1:20 Issues With Regen Braking
- 2:29 Only Small Amounts Reclaimed
- 3:44 The Return Journey
- 4:10 So Will This Get Better?
- 5:22 Wrapping Up
Hello, I’m Tristan. For about as long as electric cars have been with us, the elusive idea of an electric car that can charge itself as it goes along has also been out there. Over the years, people have had different ideas on how to achieve, or at least come close to achieving, the perpetually charging EV. So far, the idea that has gained the most traction has been incorporating solar panels into an EV’s exterior, but there’s only so much space and charging capacity before you’re back to square one.
Another big idea that’s got engineers’ imaginations going is harnessing the power of regenerative braking. Could improving technology in brake energy recuperation be the key to unlocking the EV that can charge while it’s driving? Let’s take a closer look.
Regenerative Braking for Recharge
If you drive a Tesla or another EV with regenerative braking, then you actually can charge your car while you’re driving. Well…sort of. In simple terms, regenerative braking works by using your electric motors (or at least, the electrical flow) in reverse to channel at least some reclaimed kinetic energy back into your main battery pack. Therefore, if you could engage the regenerative braking for any protracted period of time, that would essentially constitute a continuous stream of charge going into your battery, wouldn’t it?
Well…yes, and no.
Technically, regenerative braking does help to charge your Tesla or other EV as you’re driving, especially when you’re going downhill. There have been experiments done and shown here on YouTube where drivers have shown their battery percentage go up when descending long downward-sloping sections of road.
All these drivers do is get to these slopes, and then let gravity do the rest. One YouTuber tested the effect while descending a two and a half mile long downward road, wanting to see how many extra miles would be added to the car’s range after all that regenerative braking. That experiment garnered an additional 3 miles onto the car’s “remaining range” reading.
So, if it works, why was my answer “yes, and no” before?
You may have noticed that I started the previous point with the word ‘technically.’ That’s the key here. Yes, technically you are charging your EV when you coast along using the regenerative braking like this, but there are two quite big problems standing in your way:
1. The Amount of Charge is Small
The most important factor is that as things are right now, the amount of electrical energy that makes it from the electric motor into your battery is very small. We have to remember that we’re working on reclaimed energy here, so it’s all subject to the law of diminishing returns.
An electric motor’s current running in reverse, even using the most cutting-edge technology, is only going to capture a maximum 70 percent of the kinetic energy that is being given off. After that, more is lost as only a portion of the captured energy makes it back to the battery, with some being lost as heat. All this time, your car is still expending battery energy just by keeping everything in your vehicle working. In other words, the heating or air con, infotainment screen, ancillary systems… they all still consume electricity, of course.
The result? Well, those experiments we mentioned showed real gains of miles and battery percentages, but what do those numbers really mean? The reality is that while your battery percentage number may jump up 2-3 points, or your mileage increase by 2-3 miles, those numbers can disappear just as fast — or even faster — than they appeared in the first place.
2. The Return Journey
Next, you may have regained all that power going downhill in the first place, but what about when you’re on your return journey? You’ll have to travel up that same hill, likely expending all the energy you regained, and then some. Even if you’re coasting down a hill on your way home, thinking you’re getting a jump on your overnight charging, you likely had to climb that hill on your way to wherever you were going.
Unfortunately, Tesla, GM, Ford, Honda and other OEMs have yet to build automotive technology that can truly defy the laws of physics. Every action has an equal and opposite reaction. Except in the case of EVs, you might find that it’s not so equal, and you actually end up with net losses…especially if you use a lot of your EV downtime to run the Tesla “Caraoke” system!
Will Things Get Better?
There’s no doubt that regenerative braking technology will continue to improve, just as it has been for the past few years. If you can cast your minds back to when this technology was confined to hybrids, people hated it because it made the brakes feel a bit spongy and even unsafe. It has since become far more refined and efficient, not to mention a great way to save wear and tear on your regular hydraulic brakes.
As to its potential for developing the perpetual EV, it definitely has a part to play, but it likely won’t be the definitive element that brings it all together. But who knows? With better integrated solar technology, enhanced regenerative braking, more powerful and efficient batteries, and some new innovations (such as wind capture, mini fission reactors and of course caraoke power), we might just see the range of EVs massively increase.
At the end of the day, we’re still bound by the laws of the universe and the ever-present issue of diminishing returns. Charging on the road remains an elusive but desirable goal, not because we should be building cars that run forever, but because we want EVs that can eliminate range anxiety, and that better integrate into our new idea of a more sustainable world.
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