Simple DC/BEV "Cruise Control" circuit idea

[terry.kane]

Being a newbie, I don't know if any of our present members' cars have cruise or not.  I expect not, given that CC is usually run off vacuum, I believe.

Here's the thought:

1. Assuming the throttle is nothing more than a 0-5kΩ potentiometer (or the like):
2. Install a second 0-5kΩ potentiometer in the dash, (to be marked off in speeds in high gear)
3. Next to the pot knob, a momentary contact push button (normally open) (could have a pilot light to indicate cruise)
4. Behind the scenes - a 12V DPDT relay on a start-stop-stick circuit
5. The normal (unenergized) position of the relay sends the throttle pedal resistance signal to the controller
6. The made (energized) position of the relay sends the dashboard potentiometer resistance signal to the controller (cruising/throttle lock) - Speed up/slow down by turning knob only in this mode - nice!
7. While driving with the throttle pedal and in high gear, turn dash knob to desired "speed" and push button
8. Controller now reads dash pot (lol for you ME/EE geeks in the crowd) resistance and you're "cruising"
9. For safety/convenience, the stick circuit is interrupted by a tap on either the brake or throttle pedals (using normally closed micro-switches wired in series in the relay s-s-s circuit on the pedals) and the controller reverts to throttle pedal pot signal.

Granted this isn't speed-sensing/feedback loop true cruise control.  It's merely a throttle lock so the car will speed and slow with the terrain.  I had a gas pedal throttle lock on an old ICE car of mine (with the same brake pedal safety shut-off) and it worked quite well.  You actually get better gas mileage when you don't 'pump the gas' and I expect EV's would yield the same benefit by not constantly 'modulating' the throttle but rather fix it at one input for long periods.

I'd love to hear comments on this idea. I may post a schematic if I can channel my inner EE (long-slumbering since 1989).

-TK

[wayne.mcguire]

SOUNDS LIKE GOOD IDEA. AND SIMPLE.  WE DO SIMILAR CIRCUITS FOR PROPORTIONAL CONTROLS IN THE HYDRAULIC FIELD.  WORKS WELL.

WAYNE

[rich.rezny]

I don't have a EV yet but I've read alot about driving tactics of an EV. Coasting is one of the ways an EV can go further on the limited battery capacity.  With a cruise system the controller would be operating at partial load more than it needs to be to and power would be wasted.  I remember going to the train musuem in Union, IL. The trolley car engineer told me that he would initally power up the traction motors at 1/4 rate (resistor type controller) to get the car rolling without jerking too much. Once rolling he would go thru the 1/2 and 3/4 rates pretty quickly to full on power then back to 0 and let the coach coast to the next stop. On a long run he would go back to full on power in bursts to keep the car going.  I have been practicing this driving tactic with my ice car at times just to feel what it would be like to drive an EV (the engine is still running though at idle). The quietness is great!!! (even with the diesel engine of my car idling).