Throttle pot / speed controller Motor not stopping

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RH
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Joined: 11/05/2007
Points: 4

Hello, I have a problem with an E-Star 36 volt gokart.
When the throttle is not engaged( pot is at approximately zero) the motor keeps turning at a low rpm. Maybe a couple of MPH. The throttle pot/speed controller works fine on acceleration and deceleration. As soon as I turn on the power the motor engages.
The cart has a Kango speed controller.
A new 5K Vishay spectrol pot digi-key p/n SP657-5.0K-ND.
Batterys are fresh and charged Power Sonics.
The kart is the the same as the posting by MarxNuts on 9/23/2007 except it has no reverse. That posting provides a drawing of the circuit.
Any advice would be greatly appreciated. Thanks RH

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marcus
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Joined: 09/16/2007
Points: 19
Re: Throttle pot / speed controller Motor not stopping

inside the controller there is a gain control pot, sounds like it needs to be tweeked.
you will need to open the controller, power up, find the little pots and tweek them.
there might even be a ramp control pot. that would be fun.

reikiman
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Joined: 11/19/2006
Points: 8454
Re: Throttle pot / speed controller Motor not stopping

To make sure I looked up your part number on digikey. You do mean the product named '1W Industrial Rotary Position Sensor' on this page?

http://digi-key.dirxion.com/Main.asp?from=emailafriend&pagenav=&bookid=1&pageindex=1806

If so, this isn't a typical throttle arrangement. A typical throttle would be a) a handlebar mounted twist grip that embeds the potentiometer in the twist grip, b) sometimes the handlebar throttle uses hall effect rather than resistance, c) sometimes the handlebar throttle is arranged as a lever the thumb rests on rather than a twist grip, d) a motorcycle-style twist grip that operates a cable that then operates a 'POT BOX' ... there are some examples here: http://www.evparts.com/shopping/index.php?id=540

I have the last on my Lectra motorcycle.. a motorcycle twist grip, with a cable, that goes to a POT BOX. I've had the behavior you describe if the cable is not seated correctly in the POT BOX and therefore the potentiometer inside the POT BOX is turned a little bit.

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rgx
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Joined: 11/21/2006
Points: 137
Re: Throttle pot / speed controller Motor not stopping

Without knowing anything about the Kango controller or the cart, I suspect this could be a feature. Some EV controllers have this function, to emulate the behavior of a car with automatic gearbox. At zero throttle the motor will start pulling and with no brakes applied, car(t) will start moving slowly. (Maybe not the most likely cause of the fault this one, but if you find no other explanation you might want to check this as well.)

RH
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Joined: 11/05/2007
Points: 4
Re: Throttle pot / speed controller Motor not stopping

- What would be the best approach to opening the controller? The cover is a approximately two inch high thin plastic case epoxied to the plate. I am thinking of trimming off just the top. Is there any wiring that might be caught. I have been trying to find info on the controller but have had no luck.

- That is the pot I have on the cart. I gave a visual on the kart to look for any evidence of wires or additional control items that may have been removed or broken off and I didn't find any. Also the cart pretty much lines up with the drawing provided by MarxNutz.

- I hope that the people who designed the cart wouldn't let a potential hazard like that slip through. To be able to just enable the power switch and have the cart move would be pretty bad enginnering. Would a switch at the pedal that shuts the cart off when the pedal is returned be an option? I dont really like the idea of shutting the cart on and off multiple times whenever it is driven.

Thanks to all for your advice. RH

MarxNutz
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Joined: 04/29/2007
Points: 29
Re: Throttle pot / speed controller Motor not stopping

Did you ever get a definitive answer to your question? I was reviewing information about the Kango when I came across your post, and wondered about your problem... My controller went to my stepfather, who just recently installed it in an old EZ-Go golf cart. He did not report any similar problem, so I can't really say that it was SUPPOSED to pull like that. My bet would be that the cable going to the pot linkage was too taut, therefore not letting the pot go all the way to 0. You could try loosening the nut and let a small bit of slack into cable, then retighten. Please let me know if that works. If you get fed up with it, I'll take the whole thing off your hands LOL...

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RH
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Joined: 11/05/2007
Points: 4
Re: Throttle pot / speed controller Motor not stopping

My solution to the problem was to wire in a microswitch at the pedal from the power button on the steering wheel . When the pedal goes to the stop postition the switch shuts off the power. It works quite well. I did crack the case of the speed controller and took a pick inside but I decided not to try and open it. The cover is heavily epoxied onto the base. If I had a spare controller I would have tried it. There was nothing wrong with the throttle pot or the mounting so I do believe the issue is in the controller. If you broke up your cart do you have any components you would want to sell. I dont have reverse but am planning on installing a mechanical forward/reverse switch from a golf cart that I bought on ebay. I did notice you had reverse circuitry on your cart. How much if any info have you found out about these go karts and their components. You are the only person I have found who has any knowledge of these machines. Thanks for your interest. RH

MarxNutz
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Joined: 04/29/2007
Points: 29
Re: Throttle pot / speed controller Motor not stopping

In my case, the pot was bad. The controller turned out to work just fine, in fact it was a 48 volt 300 amp (possibly Curtis)! Stepfather says when he finishes building another controller I can get that one back! So, it goes towards future project, probably a motorcycle. I may also get the solenoids back, so I will let you know. I don't have anything else, except the little panel with the key switch and reverse button, and the Anderson-style charger connector. I'm glad to hear you solved your problem, I hope you get some enjoyment out of your kart.

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