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BrianG · 02.25.2009, 11:02 AM

A looong time ago, I too thought that motor braking was achieved by the ESC partially shorting the phases via PWM. Due to the way ESC FETs are wired to the motors, this would be done by turning on all the FETs going to ground. But, doing this would generate no voltage/current. And as you can see via my original post, the ESC does generate both voltage and current. The numbers don't lie boys. The fact that I got a higher voltage than the supply (battery) and negative current (current flowing into the battery rather than from the battery) both indicate, without a doubt, that there IS regenerative braking.

However, Patrick has said the ESC sends the motor's kinetic back into the ESC and then to the battery. If this is happening (and it is), simply shorting the windings would not accomplish this. Shorting the windings would brake the vehicle, but where is all that kinetic energy going? I'll tell you; either the motor and/or ESC. Neither are sized to simply dissipate that power.

There is a graph (in a previous post) by othello which proves regen braking as well.

Even Mike agrees with the results. He has Eagletree graphs where the mAh consumed is greater than the battery capacity. As well all know, when you have any decent current flow, the mAh used will actually be LESS than battery capacity. So, even though ET doesn't show negative current (does show v spikes though), just the fact you get more mAh is a giant red flag in favor of regen braking.

jhautz: why you get less runtime with motor braking is still puzzling to me. Without a consistent and repeatable test method, results are simply objective. Not trying to shoot ya down, just my $0.02.

	(#27)
BrianG RC-Monster Admin Offline Posts: 14,609 Join Date: Nov 2005 Location: Des Moines, IA	02.25.2009, 11:02 AM A looong time ago, I too thought that motor braking was achieved by the ESC partially shorting the phases via PWM. Due to the way ESC FETs are wired to the motors, this would be done by turning on all the FETs going to ground. But, doing this would generate no voltage/current. And as you can see via my original post, the ESC does generate both voltage and current. The numbers don't lie boys. The fact that I got a higher voltage than the supply (battery) and negative current (current flowing into the battery rather than from the battery) both indicate, without a doubt, that there IS regenerative braking. However, Patrick has said the ESC sends the motor's kinetic back into the ESC and then to the battery. If this is happening (and it is), simply shorting the windings would not accomplish this. Shorting the windings would brake the vehicle, but where is all that kinetic energy going? I'll tell you; either the motor and/or ESC. Neither are sized to simply dissipate that power. There is a graph (in a previous post) by othello which proves regen braking as well. Even Mike agrees with the results. He has Eagletree graphs where the mAh consumed is greater than the battery capacity. As well all know, when you have any decent current flow, the mAh used will actually be LESS than battery capacity. So, even though ET doesn't show negative current (does show v spikes though), just the fact you get more mAh is a giant red flag in favor of regen braking. jhautz: why you get less runtime with motor braking is still puzzling to me. Without a consistent and repeatable test method, results are simply objective. Not trying to shoot ya down, just my $0.02.