How Brakes on Electric Cars Are Different

AutoGuide.com Staff
by AutoGuide.com Staff

Automotive brakes haven’t changed much in nearly a century. Decades ago, engineers came up with a great system, and have largely stuck with it. With the dawn of electric vehicles, automakers had the opportunity to reinvent the system. But they decided not to. Instead, they made small changes and improvements, but left the core parts the same. Take a break and learn how brakes, how EV brakes are different, and why NRS galvanized brake pads are the perfect choice for electric vehicles.

The brakes in a car, SUV, or pickup are called hydraulic brakes. They use hydraulic pressure to push a braking material surface against a metal rotating part. In a car with disc brakes, a bracket called a caliper squeezes two brake pad surfaces against an iron rotor. The rotor is attached to the hub and spins at the same speed as the wheel.

Squeezing the brake pad against the rotor creates heat. Your forward motion becomes braking heat, and you stop. Credit here to the first law of thermodynamics that says energy cannot be created or destroyed, only changed from one form (momentum) into another (heat).

It’s a tremendous amount of heat, with your brakes reaching 400 degrees or even hotter. Race cars can see temperatures over 1,000 degrees. Your brake pads wear down to help keep the friction surface fresh, but also to help dissipate some of that heat.

So, to recap, you push a pedal, that pedal pushes some fluid, and your brake pads clamp against your brake rotors. Then you stop.

The system requires little maintenance because they’re almost always in use. Sure, rust can form overnight – just look at your brakes after a rainfall – but the first time you use them all of that rust is scraped away. That corrosion will be important later, and is why NRS developed galvanized brake pads to replace conventional painted pads.

So what’s different about the brakes in your EV? In the basic part of the system, almost nothing.

Your electric vehicle still has a brake pedal, hydraulic brakes, and disc brake calipers that clamp your brake rotors to help you stop.

But EVs have an extra system, one that is a complete game-changer when it comes to stopping.

The system is called regenerative braking. It uses your EV’s electric motors to stop your vehicle instead of just making it go.

An electric motor and an electric generator are basically the same thing. This means that the electric motor that gives you power when you’re driving can actually generate power to send to the battery when you’re slowing down.

It works automatically, though the vehicle’s computer system can change how much of your forward momentum is turned into electricity (and how quickly it happens) by changing how much power the motor is able to make and send to the battery.

So every time you lift off the accelerator or gently apply the brakes in your EV, you’re recovering up to 70% of your forward momentum as electricity to put in the battery. Instead of wasting it as heat that is sent into the air.

Then why does your EV need regular hydraulic brakes?

Because regenerative braking is limited. It can’t stop a vehicle as quickly as hydraulic brakes because of limits to how much power it can recover. So in an emergency, you still need hydraulic brakes. Regenerative braking is also limited by the capacity of your EV’s battery. If you’ve ever headed downhill with a full charge, you’ve probably noticed there is very little regen when you let off of the accelerator. The same can happen at very low temperatures and after some steep hills.

This mix of braking systems is great for you the driver, but it has some maintenance needs a gas car isn’t likely to see.

That rust that builds up in hours in a gas vehicle still builds up in an EV. And while it might get scraped away from the rotors, the brake pads and calipers don’t get hot enough to remove rust and moisture.

Using conventional brake pads on an EV can lead to premature brake pad failure caused by that corrosion. Increasing your maintenance costs and possibly even leading to brake failure.

It’s why NRS developed brake pads that are different. Made for EVs, they are galvanized instead of painted. With a galvanized finish, brake pads don’t corrode, crumble, and fail prematurely, requiring extra and expensive maintenance. You can use your regenerative braking every day and know that your NRS EV brake pads are there waiting for that hard stop.

AutoGuide.com Staff
AutoGuide.com Staff

More by AutoGuide.com Staff

Comments
Join the conversation
2 of 14 comments
  • Doug Grove Doug Grove on Feb 11, 2023

    Braking does not simply convert momentum to heat. The vast majority of the energy is transferred back to the Earth.

  • William Walker William Walker on Apr 18, 2023

    Is there no hydraulic brakes operated with a servo, or is it an electric motor ?

Next