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Discussion Starter #1
if i understand regen correctly, when i take my foot off of the accelerator my phev reverses the motor making it a generator and charges the battery. the dial shows “mild” regen. at moderate to highway speed if i then step on the brake i’ll get strong regen. i would expect the regen to vary with the speed of the tires turning the motor/generator so how does pressing the brake pedal increase the regen? and what is strong regen, higher voltage? thx.....
 

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Pressing the brake pedal, at first, doesn't activate the breaks. It actually controls the switch between motor and generator. As you press harder, the physical breaks do work.

And, yes, wheel speed is proportional to re-gen power.

This is a very simplistic version, there's tens of thousands of code running those systems.
 

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Also, the level of regen is proportional to how hard you press the brake pedal. Press it harder, the stronger the regen, up to the limits of the motor. Once you're reached that limit, then the mechanical brakes are activated, regardless of your speed. As noted, higher speeds will give stronger regen. Above about 40 MPH or so you can peg the regen level on the power display, but at slower speeds it won't reach full scale.

And regen stops completely around 5 MPH or so. So you can't completely stop the car with only regen. With some EVs that is possible, and you might hear it referred to as one foot driving. You can drive and stop without ever using the brake pedal. But I don't think Kia offers that in the Niro EV.

When regen increases, you are getting a higher current flow back into the battery, not voltage. Same as when you plug the car into a charger. It can vary the current level, but the voltage remains reasonably constant.
 

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With some EVs that is possible, and you might hear it referred to as one foot driving. You can drive and stop without ever using the brake pedal. But I don't think Kia offers that in the Niro EV.
Yes you can stop the EV without the friction brakes by using the left paddle on the steering wheel, so one foot driving is a reality.
Obviously the motor has so much braking power, so when approaching a traffic light at max speed you may not have enough distance to stop the car without using the friction brakes (brake pedal using foot). In 75% of the times I can just use the left paddle to stop the car. Once the car is stopped, it will also not creep if you let the paddle go, it will hold its position due to the resistance of the motor now being a generator. You need to be careful, if you are stopped on a downhill, the resistance may not be enough. But the car has auto hold feature, which will apply the friction brakes for you.
The Smart Cruise Control is so well programmed that it will stop the car while minimizing friction brakes and maximizing regen braking. And hold the car. A simple tap on the throttle or a flick of the incr/decr switch of the cruise control will get you moving again with SCC doing the 'hard' work of maintaining speed and safe distance.
 

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In the attached graph you see battery power during my typical morning commute in my EV. Negative means regen power.
The first 9 minutes is hilly terrain hence the higher power usage but also regen. At the 19 min mark I need to go over another hill. Around 26 min into the commute I hit the highway with speeds of 110-120kmh with SCC on. The last two big peaks is going at 120 kmh over a big bridge which oddly enough has 2 inclines. The around the 42 min you see a massive regen peak, this is me getting off the highway (using SCC) and coming to full stop at the end of the ramp.

PS We can use the HOV lanes on highways with EV and PHEV so this lane is pretty empty during rush hour...hence the high speed :)
 

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Discussion Starter #9
i think i found it: when you take your foot off of the accelerator the motor switches from driving the wheels to a generator driven by the wheels. as a generator it charges the battery at some preset power level. pressing on the brake pedal increases the power to the battery. increasing the power slows the motor which increases the deceleration of the car.
 

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i think i found it: when you take your foot off of the accelerator the motor switches from driving the wheels to a generator driven by the wheels. as a generator it charges the battery at some preset power level. pressing on the brake pedal increases the power to the battery. increasing the power slows the motor which increases the deceleration of the car.
Close, increasing the power generated to the battery doesn't by itself slow the motors, the simple fact that it takes more power (in scrubbing speed) to make more power that the system sends to the batteries is what causes the car to slow down.

Look at a home generator, a 2000 watt generator can get by with a 6 or 7 horsepower motor, but a 5500 watt generator uses a 20 horsepower motor. The reason is simply that making power takes power.

But your thought process is correct.
 

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i think i found it: when you take your foot off of the accelerator the motor switches from driving the wheels to a generator driven by the wheels. as a generator it charges the battery at some preset power level. pressing on the brake pedal increases the power to the battery. increasing the power slows the motor which increases the deceleration of the car.
Pressing harder on the brake pedal increases the amount of regen, up to the limit of the motor and the car's programming. Once you hit that limit, the mechanical brakes begin assisting the stop. BEV motors have more power, and are capable of a higher level of regen than our HEV and PHEV models. But even a BEV has a limit on how much regen it can generate.
 
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