Regen braking: confirmed!

[Arct1k]

I also think people are getting confused between energy transfer in this thread.

The car when moving has kinetic energy : E = Mass * Velocity * Velocity

That kinetic energy can only either be transferred into heat, electrical energy or potential energy (coasting up a hill) (ok light too)...

In the case of a mechanical brake it is always transferred into heat in the brake pad whilst with motor breaks some is transferred into electrical energy.

Second consideration is Newton - i.e. equal and opposite forces required to stop the vehicle.

In a mechanical setup the force is supplied by brake disk which is pressured by a servo which is powered by the battery.

In an electrical setup the force is supplied by the motor - This is where is gets interesting! How is the force generated!?*&^!

Option 1) Through converting the motor into a generator? Which would generate electricity and through losses heat but "not take" energy from the battery
Option 2) Applying power to the motor with an opposing polarity which would "take" energy from the battery
Option 3) Or a fancy combination of both...

Guessing how smart patrick is it is 3... Thats my take...

[teknorc]

Originally Posted by Arct1k

I also think people are getting confused between energy transfer in this thread.

The car when moving has kinetic energy : E = Mass * Velocity * Velocity

That kinetic energy can only either be transferred into heat, electrical energy or potential energy (coasting up a hill) (ok light too)...

In the case of a mechanical brake it is always transferred into heat in the brake pad whilst with motor breaks some is transferred into electrical energy.

Second consideration is Newton - i.e. equal and opposite forces required to stop the vehicle.

In a mechanical setup the force is supplied by brake disk which is pressured by a servo which is powered by the battery.

In an electrical setup the force is supplied by the motor - This is where is gets interesting! How is the force generated!?*&^!

Option 1) Through converting the motor into a generator? Which would generate electricity and through losses heat but "not take" energy from the battery
Option 2) Applying power to the motor with an opposing polarity which would "take" energy from the battery
Option 3) Or a fancy combination of both...

Guessing how smart patrick is it is 3... Thats my take...

Option 3 is my guess too. I acknowledge that regenerative braking is happening (I'm really not arguing that point, reread my post). Brian's test proves there is extra energy for a brief time while braking. But I think some other power or force is also needed to stop the car in most situations, that's all I am trying to say.

[lutach]

I think that regen can be more of a marketing thing than anything else. What I've noticed is that the ESC will send send energy to the motor to brake it and that can be seen in most graphs, but there might not be any AMPs going back to the battery. Our little motors as you guys know are basically like an alternator and can be used to make electricity. An alternator can be modified to be a motor and I've seen some. Even in a full size electric vehicle, regen is more for marketing. Now what is different about a full size car is that they can coast much more then our R/C vehicles and that might help them put back a little energy into their pack, but not enough to give it a good charge. So regen braking is more marketing then something practical for our hobby. Brian, a good test to see is spinning a brushless motor and see what kind of reading you get from it.