# Manual Motor Runaway protection



## cdtomlinson (Apr 3, 2009)

I am working on a '94 Saturn conversion with a 5 speed and I understand I won't need the clutch with my EV. I was thinking about removing the clutch pedal since I won't need it, but was wondering if anyone thought about using it as a way to break power to the motor in an emergency. I feel there should be some kind of emergency off switch in case of a stuck contactor or such. It seems such a simple thing to set up, making it mechanical instead of electronic, so you have one less thing to fail.

Suggestions??


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## judebert (Apr 16, 2008)

Yes, it could be considered a safety disconnect. Of course, if you ever use it that way, the motor will likely spin itself to death. 

The more common approach is to wire two contactors in series. That way if one gets stuck shut, the other will still break the current.

Additionally, a correctly-rated fuse or two and a breaker will take care of stuck-on failures before you can even react to them yourself. My breaker is mounted under the car, with the handle sticking up just under the emergency brake. That way I can use it as an emergency disconnect if *everything* else fails.


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## m38mike (Dec 27, 2008)

Aren't you concerned that you, or perhaps your mechanic, would try to use the clutch and shut down the whole vehicle accidently? I prefer to have a mechanical shut-off switch that is clearly identified and only used for that purpose. I don't trust to electrical relays (contactors) because if one can melt, then the other one can too. 

I use a breaker that is within easy reach. It should go automatically, but if something starts to melt down without causing the breaker to trip, then I can break the current manually and make things safe.


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## cdtomlinson (Apr 3, 2009)

That was the idea I started with, to have a mechanical breaker of some sort, rather than an electrical one. My first thought was a big red e-switch like they had on all our equipment in the Air Force years ago, but they are ugly and stand out. I want something to break current quickly that would be at least somewhat blend into the car.


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## grayballs (Aug 27, 2008)

cdtomlinson said:


> My first thought was a big red e-switch like they had on all our equipment in the Air Force years ago, but they are ugly and stand out. I want something to break current quickly that would be at least somewhat blend into the car.


I tend to have enough trouble finding light switches, wiper switches, etc. as well as the stick/auto issue, when I move from one of my vehicles to the other (muscle memory is the second thing to go with age)... I kinda like the idea of that BIG RED button in my EV.


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## tj4fa (May 25, 2008)

grayballs said:


> I kinda like the idea of that BIG RED button in my EV.


Me too!


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## cdtomlinson (Apr 3, 2009)

My original thought was not to keep the clutch and disengage the motor, but to use the clutch pedal instead of a contactor to disengage the electricity to the motor. I feel much safer with a mechanical disconnect than an electrical one.


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## grayballs (Aug 27, 2008)

cdtomlinson said:


> My original thought was not to keep the clutch and disengage the motor, but to use the clutch pedal instead of a contactor to disengage the electricity to the motor. I feel much safer with a mechanical disconnect than an electrical one.


 
My 'panic' button is a circuit breaker, as well as a manual disconnect.


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## Qmavam (Aug 17, 2008)

cdtomlinson said:


> I was thinking about removing the clutch pedal since I won't need it, but was wondering if anyone thought about using it as a way to break power to the motor in an emergency. I feel there should be some kind of emergency off switch in case of a stuck contactor or such. It seems such a simple thing to set up, making it mechanical instead of electronic, so you have one less thing to fail.
> 
> Suggestions??


Nothing wrong with a high current knife switch mechanically connected to the clutch.
Oh! and paint the pedal red.
Mike


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## caramelzappa (Mar 5, 2009)

Painting the pedal red is an awesome idea.


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## Jimdear2 (Oct 12, 2008)

grayballs said:


> I kinda like the idea of that BIG RED button in my EV.


If you like Big Red Buttons take a look at the Albright SD series of contactors with a built in disconnect including a Big Red Button.

http://www.albrightinternational.com/files/downloads/catalogues/SD200 LEAFLET.pdf

Kind of a nice combo unit. The contactor has same voltage and current carrying specs as the Albright SW series that many people use. Plus it has a Big Red Button on top for a fully mechanical disconnect.

Even with the contactor powered, hit the button and instant disconnect. They even have a version with a key lock. 

The unit is smaller then the old SW series, somewhere between the Tyco and the SW. Considering what you get, the price is good. 

I got mine and am very satisfied.


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## Voltswagen (Nov 13, 2008)

A manual disconnect is also handy to have when working on your EV. It allows you to remove the battery pack voltage from the terminal that wants to weld your wire crimper tool.
BTDT


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## cdtomlinson (Apr 3, 2009)

Something like the knife switch and painting the pedal was the original idea. In case of run away, I want it instantly dead. And if someone else were driving the car, I think pushing in the "clutch" would be natural, thus safe for the uninitiated. Any ideas on a source for a high current knife switch? How many amps?


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## Salty EV (Jun 8, 2009)

I am also looking for a heavy duty kill switch of some sort, preferably something I can pull out leaving a large gap between the +/-.


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## MrRoboto (Feb 1, 2009)

Search for live wire guillotine/cutter. You can find CO2, explosive charge or spring actuated ceramic blades in non conductive housings that will that cut wire and stop current some reliably. I don't know about the idea of using the clutch for a hard cutoff though, it's completely automatic for me (and I imagine many others) to depress the clutch in a braking situation, I think it may be more trouble then it's worth.


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## Watt-a-mezz (May 20, 2009)

Salty EV said:


> I am also looking for a heavy duty kill switch of some sort, preferably something I can pull out leaving a large gap between the +/-.


Hello,all. I wanted to use the 160v circuit breaker for my 88 nissan, but there was no place to install it (plus my budget wouldn't allow it) I found enough room in a protected area by the seat for an anderson disconnect. That way if the worst happens, I can reach down and give it a pull, and shut down the power. Maybe something like that would work for you. Good luck.Watt


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