10.31.2016 - by Mary Kathryn Campbell
Ask the EV Experts: Riding Brakes Downhill

First up on our new series, Ask the EV Expert, we field a question from Dave in Arkansas. Have a question of your own? Post it on Facebook, Tweet at us or email us at info@pluginamerica.org #AskTheEVExpert

I think I read somewhere we should ride our electric car’s brakes downhill to regenerate energy for the battery. Is that right?

Question:
I think I read somewhere we should ride our electric car’s brakes downhill to regenerate energy for the battery. Is that right?

Answer:
What you are describing is known as “Regenerative Braking” and is one of the coolest features of electric cars! Regenerative Braking, or “Regen” for short, allows electric cars to recapture energy that is wasted when braking. In a gas car, the act of braking is an attempt to absorb the energy of the car moving forward – in effect, stopping it. However, the energy absorbed by the brake pads isn’t re-used by the vehicle; instead, the energy is transformed into heat – that’s why the brakes get hot.

In an electric car, the inertial energy of the car moving forward can be re-used! When an electric car driver eases off the accelerator, the electric motor is instantly transformed into an electric generator. In effect, the wheels of the car are turning the motor, which is generating electricity that is then stored in the battery. This system is so efficient that most electric cars utilize this type of “motor braking” if you will, when the driver presses down on the brake pedal.

As a result, riding your brakes down a hill in an electric car doesn’t hurt the disc brakes like it would in a gas car because the electric car only uses the friction disc brakes when the driver needs to stop the car quickly or to hold the car at a complete stop, saving drivers lots of money in brake jobs!

Additionally, most electric cars are also equipped with a special “Regen” or “Low” mode that allows for a larger amount of energy to be reabsorbed back into the battery. Because there is more energy being absorbed, there is more braking force, and many electric car drivers can do what’s called “one pedal-driving” where they only need to press the accelerator to go faster, and rely on this “Regen” mode to sufficiently brake the car. So, yes, go ahead and ride those brakes down the hill and enjoy some free electrons!

4 comments on “Ask the EV Experts: Riding Brakes Downhill”
  1. Scott says:

    While researching electric motorcycles(like the Zero), I found that they generally depend on air cooling and tend to overheat/lose power in environs over 90 F. Living in Arizona, where it’s over 100 F for half the year, this put a damper on my enthusiasm. Do many electric cars have the same problem? I’ve been looking at the Electra Meccanica Solo, but as Canada is a cooler landscape and their cars don’t even come with AC standard, they might not even think about testing in 100+ heat. Any advice?

  2. Ken says:

    I have a 2008 prius.. and since we will be buying a new car this next summer. I am considering converting my prius to a Plug in with a solar panel roof.. there use to be someone that sold kits for the transformation and also did installation.
    that company has long since closed its doors.. is there anyone that still does this. if so who and how much is the installation..

  3. Phil Manke says:

    I have an electric car, and I have researched many before buying it. I do NOT know of any currently made that require the driver ti ‘ride’ the brake to regen! On most electrics, the “regen” feature is setable for amount wanted and is automatic. It was learned early on that instant regen is preferred and allows more responsive and efficient driving. My car is primarily a ‘single pedal driven’ car. The car will drag down to 5 mph just by letting up all the way on the “go-bar”. It’s like driving a ‘stick-shift’ car in second gear. I love it and the efficiency it provides.

  4. Dave Salzman says:

    I have been wondering if there is a way to upgrade my 2013 Nissan Leaf so I can get the full output of the motor/generator when in regen? As it comes from the factory it will do 30KW. Chevy. Bolt will sport one pedal driving and I’m lazy enough and cheap enough to want that.
    Thanks,

    Dave

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