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Only_Outcome4297 t1_ja30s0r wrote

Motors and electric generators are the same thing. If you apply power then it's a motor. If you spin it up without giving it power then it becomes a generator.

So in an electric car (EV), when you slow down the momentum of the car is used to spin the motor(s) to generate electricity, which is then used to charge the batteries. Because you're converting energy (the vehicle kinetic energy into electrical energy) it has the effect of slowing the car down. Depending on the use case, you can increase range by about 20% by doing this.

There are situations where regen isn't used - emergency stops and when the battery is full. In those cases the normal brakes are used.

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BackyardShennanigans OP t1_ja316a1 wrote

Ty! You elaborated on some bits I was still partially confused on from the other comment

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manofredgables t1_ja3518t wrote

The absolute most basic thing to understand is that conductors(wires) experiencing a change in magnetic field concentration, will have a voltage induced in them.

In a generator, this is achieved by spinning magnets past coils.

This goes the other way as well; applying a voltage to a conductor will create a force between it any nearby magnetic field.

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ramlak121 t1_ja31yyw wrote

How does thsi relate to single pedal driving? Any time a reviewer mentions it they somehow relate it to regenerative braking for some reason

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Only_Outcome4297 t1_ja32b2y wrote

The idea behind single pedal driving is that the Accel pedal also operates as the brake pedal. So if you put your foot down it accelerates the car, and when you lift it up it slows the car down. In an EV, it uses a combination of regen and normal (foundation) brakes to do it. The system is typically called brake blending or regen blending.

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ramlak121 t1_ja39u8j wrote

thanks!

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Only_Outcome4297 t1_ja3bo3r wrote

One additional point with noting is that there is a limit to how much energy you can capture during regen - you fairly quickly reach a point where you're putting too much power back into the battery, which risks overheating the batteries and causing damage. It's no different to having a maximum charge rate when you plug the car into a charger. Heavy regen can also cause stability issues, especially on rear wheel drive vehicles - you can't only brake the rear axle without destabilising the car, so the front also has to be braked using the normal brakes.

On most cars, that limit is in the range of a braking rate of around 0.3G to 0.4G. For that reason, brake blending (using both regen and normal brakes) has to be done. Although 0.4G braking is well within most normal braking events, cars will actually be able to brake at a minimum of 0.9G, and some will be able to go up over 1.2G.

Recent battery technology has improved to the point where it's not so much of a concern. As recently as 5 years ago, the max brake rate you could capture regen from was around 0.2G.

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DragonFireCK t1_ja3ck7e wrote

It’s worth noting that some hybrids will use the engine to break if the battery is full or you want more braking power than the battery can absorb, before engaging the actual breaks. This works as you get some breaking power from engaging the engine without giving it any fuel. - using mechanical force to compress the air in the cylinders. Obviously this does not work in a full electric that lacks an engine.

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Alternative-Sock-444 t1_ja52n2e wrote

I like how you spelled brake correctly once, but the other three times you used the word you spelled it break.

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