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JRscooby

Indepmo

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Joined: 06/10/2019

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Posted: 12/02/19 06:59am Link  |  Quote  |  Print  |  Notify Moderator

JaxDad wrote:



Mechanical reason # 1, EV's have motors connected directly to the wheels, if the wheels turn, so do the motors.


Your point? I know of applications where motors, and even more generators, spin with no electrical power or load applied. Maybe some friction in the bearings, the power needed to start/stop the mass spinning but don't see any problem unless the speed gets to high. And with direct drive, the only way to overspeed the motor would be to tow at higher speed than the car was designed to operate.


Reisender wrote:



I don't know what happens when neutral is selected in our EV's but it is definitely a free wheeling feel. One can shift back and forth on the fly while moving. As soon as it is in drive you can feel the regen. I have no idea what is happening mechanically though. No idea if it could be harmed while towing.


I would think that a clutch or mechanical disconnect between motor and wheel would be a unnecessary place for wear. All that would be needed to freewheel would be disconnect electricity from motor. The motor would still be making electricity, but without the resistance of battery, or any other load, it would be same as freewheeling.

Quote:

And the car has to be on and running or it applies the parking pall.


Could you explain? With direct drive any time the wheels stop, like at a light, the motor is not "running" Does the pawl engage at a stopsign?

Reisender

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Posted: 12/02/19 07:50am Link  |  Quote  |  Print  |  Notify Moderator

JRscooby wrote:

JaxDad wrote:



Mechanical reason # 1, EV's have motors connected directly to the wheels, if the wheels turn, so do the motors.


Your point? I know of applications where motors, and even more generators, spin with no electrical power or load applied. Maybe some friction in the bearings, the power needed to start/stop the mass spinning but don't see any problem unless the speed gets to high. And with direct drive, the only way to overspeed the motor would be to tow at higher speed than the car was designed to operate.


Reisender wrote:



I don't know what happens when neutral is selected in our EV's but it is definitely a free wheeling feel. One can shift back and forth on the fly while moving. As soon as it is in drive you can feel the regen. I have no idea what is happening mechanically though. No idea if it could be harmed while towing.


I would think that a clutch or mechanical disconnect between motor and wheel would be a unnecessary place for wear. All that would be needed to freewheel would be disconnect electricity from motor. The motor would still be making electricity, but without the resistance of battery, or any other load, it would be same as freewheeling.

Quote:

And the car has to be on and running or it applies the parking pall.


Could you explain? With direct drive any time the wheels stop, like at a light, the motor is not "running" Does the pawl engage at a stopsign?


Good morning. Yah. It might be a bad choice of words on my part as far as “runnjng”. So this is what happens in both our cars. Different brands. The one car literally has a key. You can not select neutral without having the key on and the car energized. No key and it is in park. The other car just senses the proximity of the key and allows the car to be enabled or energized by pushing an in button. Then you can select drive reverse or neutral. Both cars are first generation EV’s. Eg four or five years old. Things may have changed. Both have been flawless. Only maintenance has been 3 jugs of washer fluid during that time. Coming up on wipers for the one though. Tires in a couple years.

Hope that helps.

Harvey51

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Posted: 12/06/19 05:38pm Link  |  Quote  |  Print  |  Notify Moderator

Thanks for the facts in familiar units, Reisender!

On the regeneration braking, kinetic energy of the moving car is converted to electric energy by the motor and that energy must be used to charge the battery or be converted to heat to dissipate.

* This post was edited 12/06/19 06:01pm by Harvey51 *


2004 E350 Adventurer (Canadian) 20 footer - Alberta, Canada
No TV + 100W solar = no generator needed

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