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It occurred to me yesterday as I lifted off from the brake as the lights went green and the Kona started creeping forward that presumably there is energy being consumed when stationary with the brake applied.

Am I right in this or does the car know not to apply torque when the brake is applied?

Just curious!
 

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You can view energy % on the dash for the motor, heating, electronics etc.
No motion, no power to motor.

Try putting your left foot to the floor on the brake and then your right foot to the floor on the brake. Nothing happens, view the energy consumed by the motor, zero.

Then and ONLY on a straight road in the dry with a decent speed limit, REMOVE left foot from brake pedal and watch the Kw going to the motor (and watch the road ahead).
 

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Seriously - 69 kW on the motor when stationary or was that the acceleration test suggested by @Electra Glide in Blue ?
It's a page from the manual so who knows what the vehicle was doing when they took it. The reason for posting it was to correct Tandy0's assertion in the post above.

John.
 

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Interesting! There must be some sort of power going to the motor to start it turning in the very first instance. Otherwise how would it begin to turn at all and creep forward with no throttle pedal action. Unless the brake pedal cuts off power to the motor..then I could accept the process...
 

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Could it be that the car is using the electric motor to hold the car stationary by alternating forward and reverse torque?
 

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It's a page from the manual so who knows what the vehicle was doing when they took it. The reason for posting it was to correct Tandy0's assertion in the post above.

John.
Ok, that makes sense. So all someone needs to do is look at that screen when at a halt with D engaged and photograph it for the rest of us.
 

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Interesting! There must be some sort of power going to the motor to start it turning in the very first instance. Otherwise how would it begin to turn at all and creep forward with no throttle pedal action. Unless the brake pedal cuts off power to the motor..then I could accept the process...
Yes there is power going to the motor when the car creeps, though this might be a negatve value going downhill. But when you are in neutral, or using hold, or the brake pedal and stationary the dash displays zero. That could in reality mean a current draw of up to 1kw?
 

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Unless the brake pedal cuts off power to the motor..then I could accept the process...
This.
It's the same with DCT and other mechanical automatics - when you release the brake 'creep' is engaged.
(There is usually a 'hill start' override so if you hold the brake but apply throttle the clutch engages. I don't know if the Kona e does that too.)

Could it be that the car is using the electric motor to hold the car stationary by alternating forward and reverse torque?
The Kona is held stationary by the mechanical brake when auto-hold or the SCC are in use. You can hear (and sometimes feel) it. Using power for that would be wasteful.
 

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Interesting! There must be some sort of power going to the motor to start it turning in the very first instance. Otherwise how would it begin to turn at all and creep forward with no throttle pedal action. Unless the brake pedal cuts off power to the motor..then I could accept the process...
I don't know the Kona, but I guess it is the same as every other car in this respect.

There are electronics sensing the brake pedal, once the car is stopped, and you keep you foot on the pedal, or use the parking brake, the current flow to the motor(s) stop. As soon as you lift your foot, depending on how much lift, the current flow begins again. There is no magic in this, it's the same as when you switch on your light at home, as soon as you flip the switch, or turn the know, current starts flowing to you light. Of course, in a car there are some consumers even when the car is stopped, and in fact, even when you stopped it using the stop button and you are at home sleeping. Examples are: the alarm system, the vicinity sensor to detect the key, the automatic localizer, web communication interface, wifi... all these are active when the car is switched off and you are sleeping at home. If you stop at a red light the light, climate control, seat and steering wheel heating, entertainment, navigation, web communication, main computer and all the other parts and several other are actively requiring electric power.
 

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The permanent magnet motor in the Kona and many other EVs has positional feedback using a resolver. In combination with the drive electronics it has most of the capability of a servo motor such as you might find in a robot or machining centre, although the positional resolution may not be quite as high. With the inclusion of computer control there is no comparison with an ICE, it can simply do anything imaginable, including holding vehicle position with low power loss, providing zero torque which would allow coasting, or provide constant torque instantly on lift-off of the brake pedal, as it is doing in regards to the question asked.
 

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It occurred to me yesterday as I lifted off from the brake as the lights went green and the Kona started creeping forward that presumably there is energy being consumed when stationary with the brake applied.

Am I right in this or does the car know not to apply torque when the brake is applied?

Just curious!
It's complicated.

It depends on the particular motor control strategy they have opted for. There is probably 'some' active current in the motor winding (10's of, maybe 100, Watts), and the control system responds to that and it is a closed-loop feedback ensuring a minimum of power is used whilst also ready to move off at an instant.

But, no, it is not like a torque-converter automatic, if that is what you are thinking, where there is some sort of constant power loss going on. It is more sophisticated than that, and it is also probably more sophisticated than simply powering off the motor (although this is another strategy, and to simply turn the electronics on as soon as any reverse motion is detected, or in some cases not to do that .. the Fluence did not power its motor under certain conditions and would roll back on a slope).
 
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