# The "oh scheisse" bar



## electrabishi (Mar 11, 2008)

Cross posting in case there is any interest from the performance crowd:

This is my solution to the pedal fail problem as well as a full on failure problem and welded contactor problem etc etc. http://www.thefoat.com/fa/m-photo/photo_id-6826/member_id-cp+ndsLnd2IM3ohQzYqz0w== We affectionately call it the "Oh Shit!" bar.

6" of air gap in the main 4/0 cables running from the battery pack to the controller positively disconnects all power to the controller. I witnessed first hand the operation of this device in a pedal stick situation that Tim experienced in the White Zombie two summers ago. And I got to ride home with John in the Zombie after Tim did a brake stand for 500 feet at 110 mph until he was able to pull the "Oh Shit" bar. Its actually a Fuse Pull Block except we are not running a fuse in it. It just has a copper buss bar welded in place of where the fuse would go. I fuse and breaker the two packs separately nearer the batteries.

I can start stocking these at EV Components if there is any interest. It was a PITA to get. I had to talk to several folks with foreign accents ;-) Wayland had his donated and doesn't know the source. I do 

Mike

> -----Original Message-----
> From: [email protected] [mailto:[email protected]] On 
> Behalf Of David Dymaxion
> Sent: Wednesday, February 24, 2010 10:58 PM
> To: Electric Vehicle Discussion List
> Subject: Re: [EVDL] pedal failure problem
> 
> Are you sure the car doesn't mechanically do neutral?
> 
> This document seems to indicate neutral isn't electrically commanded, but rather a reported state:
> http://www.autoshop101.com/forms/h16.pdf Caveat, I don't know if this 
> covers the recalled cars. I also know the newer Prius obviously has an 
> electrically commanded neutral, the control feels more like a switch than a mechanical connection.
> 
> EV content: This is the first electronic mapping for the tranny I have 
> seen, it could be helpful to someone trying to make an automatic 
> tranny work with an EV. It might also provide info for yet another safety cutoff for controller runaway.
> 
> 
> 
> 
> ________________________________
> From: David Harrington <[email protected]>
> To: Electric Vehicle Discussion List <[email protected]>
> Sent: Wed, February 24, 2010 9:17:55 PM
> Subject: Re: [EVDL] pedal failure problem
> 
> I have heard from some reports that once the car was "run away" 
> throwing it into Neutral did nothing. And that makes sense to me 
> because the transmission is Electronically controlled, and if the 
> engine computer and lost control, so has the PCM since it's the same 
> now. One person did survive a Toyota run away, and during their 
> testimony this week they said they threw the car in neutral and it did NOTHING, just kept on going 100 MPH.
> 
> >From being a student of computer engineering, and my experience with 
> >EV's, I
> do have to say that the flaw with the runaway Toyota's has got to be 
> more in line with the engine and transmission computer, than just a sticky pedal.
> 
> In a modern car, when your turn your key off it doesn't shut off 
> power, it tells the car's computer to shut off power. Same with the 
> transmission, the shifter just tells the PCM what gear to start off 
> in, and in my EV (1996 Honda Civic) I have an automatic transmission 
> that is computer controlled, and if I miss shift, like going from 
> Neutral to Reverse while rolling forward, the PCM says "No ya don't" and won't engage.
> 
> I have two distinct safety measures in my EV. First I have my key cut 
> power to my 12 volt system, and a circuit breaker under my e-brake so 
> I can rip the e-brake and cut all power at once. And when my 12 volt 
> cuts off, the transmission automatically looses power to its solenoids 
> and disengages from whatever gear it was in.
> 
> If I owned a Toyota, I would rig up a switch from the fuse to the 
> engine computer so if it ever goes crazy, I could just kill the +12 
> from the computer.
> 
> 
> David Harrington
> 
> Electric Civic Conversion
> http://civicity.blogspot.com
> 
> -----Original Message-----
> From: [email protected] [mailto:[email protected]] On 
> Behalf Of Morgan LaMoore
> Sent: Wednesday, February 24, 2010 10:16 PM
> To: Electric Vehicle Discussion List
> Subject: Re: [EVDL] pedal failure problem
> 
> On Wed, Feb 24, 2010 at 8:45 PM, Roger W <[email protected]> wrote:
> > ...
> > I can't help but wonder how many of the Toyota drivers have thought 
> > to
> simply kill the ignition or to shift into neutral and just let the 
> engine blow. At that point - who cares about the power plant? . But 
> then, sadly, I guess that many of those who have experienced throttle 
> runaway are not present to describe their efforts.
> 
> I read that some of the models affected had push-to-start and wouldn't 
> let you turn off the car until it was out of gear.
> 
> That said, I too wonder about how many accidents could have been 
> prevented if people had shifted into neutral. When I heard about these 
> problems, I made sure that I could shift into neutral in my Scion even 
> with the throttle (lightly) applied; it worked fine. Most people 
> probably never use anything other than park, reverse, and drive, 
> though, and wouldn't think to shift to neutral in an emergency. It's 
> also possible that the cars with push-to-start also had more 
> "intelligent" transmissions that wouldn't let you shift while applying 
> throttle, though.
> 
> I wonder what percentage of EVs have sufficient safety devices to turn 
> off the car if the controller failed short; it seems to me that many 
> people may use under-rated safety components that can handle the 
> average load but couldn't handle the possible fault current.
> 
> -Morgan LaMoore


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## JRP3 (Mar 7, 2008)

Interesting, and I suppose expensive? I think I'd want a remote setup so as to keep the excitement out of the cabin


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## electrabishi (Mar 11, 2008)

JRP3 said:


> Interesting, and I suppose expensive? I think I'd want a remote setup so as to keep the excitement out of the cabin


Not expensive when compared to the value of your life if you need to be absolutely sure you can shut down a run away controller. Sure you could neatly tuck something away and remotely actuate it but if I did that I would always wonder "is that thing really going to open if I need it to, and if it doesn't what do I do then?"


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## JRP3 (Mar 7, 2008)

Well every vehicle has remotely operated throttles, brakes, e-brakes, etc. that we expect to work, and there is some danger with bringing pack voltage into the cabin. You could work out a system that would even give you a mechanical advantage when yanking the lever.


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## electrabishi (Mar 11, 2008)

JRP3 said:


> Well every vehicle has remotely operated throttles, .../QUOTE]
> 
> Which seems to be a problem for Toyota as of late  I wasn't promoting this as a primary disconnect . Thats what your "remotely" activated main contactor, main breaker and fuse are for. But contactors and breakers can weld and fuses can have some undesired delay in a full on failure situation. If installed correctly the rear mount studs on this fuse pull block keeps the traction cables out of the cabin, thus the common term for this type of pull block in the industry it is used is a "Dead Front Fuse Block"  But relying on the main contactor, breaker and fuse to open is reasonable.... until it fails or delays when you REALLY NEED IT OPEN. Remember it was a failure of something that was supposed to work that didn't that got you to that situation. There are some families of some dead folks that wish their family members car had a physical and reliable traction pack disconnect.


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## JRP3 (Mar 7, 2008)

I wasn't clear. When I spoke of remote operation I wasn't thinking of relays and such, just a a physical connection leading out of the cabin. Could be just a long bar attached directly to the handle, or a cable, something like that. I can imagine a nice big arc happening when that connection is broken under load, I'd like to keep it far away


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## electrabishi (Mar 11, 2008)

JRP3 said:


> I wasn't clear. When I spoke of remote operation I wasn't thinking of relays and such, just a a physical connection leading out of the cabin. Could be just a long bar attached directly to the handle, or a cable, something like that. I can imagine a nice big arc happening when that connection is broken under load, I'd like to keep it far away


Thos True over on the EVDL was mentioning the predecessor to the "Oh SH!%" bar used in the Zombie that sounds like what you are talking about. The thread is titled "Re: [EVDL] run away [ accelerator pedal ]" He said John was not happy with the 1st gen version and moved the the "currently" installed fuse block we are talking about. I know it works. I've seen it with my own eyes. It seems easier for me to trust when I can pull something and I know that because I have something in my hand there is no current flowing through the air gap i just created by pulling on it. I suppose you could wire into On-Star and just have them shut you down if they detect a full on failure 

With this block the arc will likely be extinguished before the plastic guard comes fully out of the socket. It was designed to do just that. This isn't just a part that happens to work for the application. This IS the application. They even sell the buss bar for you to put in place of the fuse if you just want to use it for a physical disconnect.


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## JRP3 (Mar 7, 2008)

I have no doubt your setup works. I also have no doubt that very few people are going to mount something like that in the middle of their passenger compartment.


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## 2cycle (Jul 2, 2009)

I take it none of you guys ever rode snowmobiles. Snowmobiles have had mechanical over electronic throttle overides for about 20 years now. The reason is because snowmobiles don't have a neutral gear, they have a CVT style transmission that when the throttle sticks it's full on power with just brakes to stop it unless something can interupt the ignition. Anyway my point is why not just copy what's been around for 20 years and apply it and modify it to your application. With all these electronics guys on here someone can build a cut off switch that is safer than that gigantic fuse in your hand. 
If I have time tomorrow I'll see if I can scan a quick sketch of the devices that we use.


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## JRP3 (Mar 7, 2008)

I've ridden, but nothing newer than a 1976 polaris  Regardless, what you describe won't help if your controller is locked full on and not responding to throttle inputs, you need to break the connection to the pack. Ideally your key switch will turn off the contactor, but if that fails you want to be able to physically disconnect the pack from the controller.


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## GerhardRP (Nov 17, 2009)

electrabishi said:


> And I got to ride home with John in the Zombie after Tim did a brake stand for 500 feet at 110 mph until he was able to pull the "Oh Shit" bar.


I would want something that worked automatically, so that loaning [or selling] the car to someone would not have to start with an emergency procedures lecture...so...

Make a solenoid valve with a coil that carries the full battery current.. the valve is normally closed and opens whenever "high" current flows. The valve connects the brake hydraulic line to the positive release mechanism. So if you stand on the brakes while high current flows, the circuit is forced open by hydraulic pressure.

Gerhard

PS is this patentable?
PPS A sensor for fuel flow and ignition cutoff would work for ICEs.


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## 2cycle (Jul 2, 2009)

JRP3 said:


> I've ridden, but nothing newer than a 1976 polaris  Regardless, what you describe won't help if your controller is locked full on and not responding to throttle inputs, you need to break the connection to the pack. Ideally your key switch will turn off the contactor, but if that fails you want to be able to physically disconnect the pack from the controller.


That's what I meant by modify it to fit your particular application. My thought would be along the lines of a large contact between the pack and controller that is operated with (this is where you can choose your method of controlling the contact) your device that reads a closed throttle or open throttle and if the throttle is closed but there is still voltage running through the system it trips the contact. It would happen very fast and no need for panic. 
I would not have thought so before I learned about some EV stuff but I think ICE race vehicles have WAAAYYYY more trick electronic gadgets than EV cars. I just find it a little ironic.


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## JRP3 (Mar 7, 2008)

Yeah but an EV *IS* a trick electronic gadget


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## JRP3 (Mar 7, 2008)

What you describe still relies on an electromechanical device operating properly at high amps and DC voltage, and some people don't feel comfortable with that and want a physically operated physical disconnect.


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## 2cycle (Jul 2, 2009)

I guess my idea, which is 1 of many ways one could achieve the same end result, was to use a low voltage source of sensing current and throttle position and when things didn't jive it would activate some sort of mechanism that would break the battery pack feed. Electromechanical devices made for electric busses and trains and such use these as their safety switch so I can't imagine people not trusting them, but I can envision a spring loaded break operated by electromagnets that wasn't sitting in your lap.


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## GerhardRP (Nov 17, 2009)

JRP3 said:


> What you describe still relies on an electromechanical device operating properly at high amps and DC voltage, and some people don't feel comfortable with that and want a physically operated physical disconnect.


OK, let's go one step simpler...when the brakes are applied hard, brake fluid passes through a restriction into a piston, which when filled would positively disconnect the battery (or fuel in a diesel or ignition on other ICEs). The restricting passage and piston would be sized so that,say, 10 seconds of panic breaking would trigger operation.


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## JRP3 (Mar 7, 2008)

10 seconds would be much too long, and I'm not sure how you'd regulate the time in a pressure system. I'd think it would have to be set to work at a certain pressure, but you wouldn't want it to disconnect during a panic stop when the motor wasn't in runaway. I don't think tying it to the brakes is a good idea.


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## maxvtol (Nov 11, 2009)

If I'm dodging shopping carts in a parking lot, I don't think I'll be able to find the OS bar. 

And any amount of time over instant is way too long (thinking of Prius brakes here).


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## jackbauer (Jan 12, 2008)

I'm currently testing a software modification on my version of Paul Holmes controller. If the system sees the throttle at zero but significant current flow to the motor it opens the main contactor and locks out the controller. I'm also going to incorporate a brake light switch input. If the system sees brakes on but significant motor current flowing it cuts off power. I'll be using two series connected kilovac ev200 contactors for the cuttoff.

I have several reasons why i dont like the in cabin disconnects.


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## Woodsmith (Jun 5, 2008)

I'm thinking of a parking brake lever, linked to a steel rod through the firewall or tunnel (no cables to break), attached to one half of an Anderson connector. Pull on the lever and Anderson breaks connection. The lever and steel rod connection can be made to give any suitable mechanical advantage.

An insulating cover can also be made that will drop down, spring loaded guillotine style, that blocks the arcing between the two halves of the connector and prevents reconnection without some intervention.


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## Guest (Mar 7, 2010)

You sort of read my mind . Except I am thinking of reinstalling the clutch pedal and using it as an emergency disconnect lever. I figure I am used to a standard trans in my Land Cruiser so I can slap the shifter in neutral and stomp the clutch pedal as fast or faster.


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## JRP3 (Mar 7, 2008)

Only problem with that is you could easily forget what you're doing and naturally press the clutch pedal by mistake in a non emergency situation.
Especially a problem if anyone else drives the vehicle.


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## Guest (Mar 7, 2010)

That did cross my mind. How about if I put a strap down to it with a pin that had to be pulled before the pedal can be depressed? A little cynical humor.


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## piotrsko (Dec 9, 2007)

well heck if we can be allowed to be cynical:

shaped explosive charge wrapped around the motor wire. blow it apart in panic situation. no arc, no problems, just a hole where stuff used to be.


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## JRP3 (Mar 7, 2008)

Ejection seat?


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## Guest (Mar 7, 2010)

You are not as far fetched as you think. In the 70s when Lamborghini first used the swing up doors they considered installing exploding aircraft bolts in the door hinges for emergency exit incase of a rollover.


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## Jimdear2 (Oct 12, 2008)

piotrsko said:


> well heck if we can be allowed to be cynical:
> 
> shaped explosive charge wrapped around the motor wire. blow it apart in panic situation. no arc, no problems, just a hole where stuff used to be.


 
Great idea. Aboslutely Positive Disconnect every time.

Couple of wraps of det cord around a special length of wire that is inclosed in a special explosion proof box, built to goverment specification and approved by the proper goverment agencies.

We might see one to buy in 20 years and it shouldn't cost more then three times the value of the car you want to install it into.

A golden olde.

What is a mouse built to government specifications

Wait for it



Wait for it



Wait for it

Ta Da

An Elephant

Bet you already knew that.


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## JRP3 (Mar 7, 2008)

Jimdear2 said:


> Great idea. Aboslutely Positive Disconnect every time.


Unless your detonator fails.


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## electrabishi (Mar 11, 2008)

2cycle said:


> That's what I meant by modify it to fit your particular application. My thought would be along the lines of a large contact between the pack and controller that is operated with (this is where you can choose your method of controlling the contact) your device that reads a closed throttle or open throttle and if the throttle is closed but there is still voltage running through the system it trips the contact. It would happen very fast and no need for panic.
> I would not have thought so before I learned about some EV stuff but I think ICE race vehicles have WAAAYYYY more trick electronic gadgets than EV cars. I just find it a little ironic.


Please excuse me if I haven't read through the rest of this thread yet. But I'm going to go in order here.
This is exactly what the Zilla does. When you are commanding 100% Throttle and 100 % duty cycle is achieved, every 0.01% of an on cycle the Zilla control board will tell the power section to turn of for a very brief period to see that the motor voltage actually goes to zero. If it fails this test then it will assume a full on failure and command the main contactor off. This is exactly what you are talking about. And this is what makes the Zilla controller such a safe unit. I'm not saying that it is full proof, however it is already built in. Pending that safety failing I put in the next most positive means of disconnecting the battery current from the controller. My hand puts a 6 inch air gap in the main power conductor. Maybe the majority of people, or maybe even no more people will ever put a pull block on their tranny tunnel,  but if they ever fail full on they would wish they had. 

Now back to my point. To get this safety in another controller you will need to do any or several of the procedures we are talking about. So since we are talking about those I can tell you in two separate cases where a Zilla has not actually failed full on, but the conditions existed where a Zilla controller did not shut down, one in the White Zombie where the accelerator pedal got stuck in the carpet (the Toyota failure) the pull block likely saved a life and a car. In the second (in my case on multiple times when many people saw it) through what I know now was a code problem in my controller, the Zilla actually thought it had failed full on and commanded a shut down of the main contactor under full throttle. Now you might think this is harsh on a contactor but the Zilla actually commanded the power section to turn off first, which it was able to accomplish because it hadn't actually failed, and then commanded the main contactor to open. So with wheels in the air and 1500 ft-lbs of torque on the driveline, the car shut down and rolled maybe another 20 feet.

So I know the safety mechanism in this controller works, and I know that if it doesn't a GEC pull block will. Knowing this, not only can I not race anything other than a Zilla controller at the current time (so to speak) but I have to use the tried and true method of last resort.

Now you may say that you are not racing, but I would say that even if you only have a 1000 amp controller, if it fails full on you will want to be absolutely sure your method of last resort will absolutely disconnect power to your controller, aside from the automatic methods. I am even saving up to buy one of these blocks for my daily driver since I cannot reach the breakers and I'm only relying on Zilla safety feature and the and the key input (which both rely on the main contactor alone to open) to shut the truck down. 

Just some thoughts.

Mike


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## electrabishi (Mar 11, 2008)

2cycle said:


> I guess my idea, which is 1 of many ways one could achieve the same end result, was to use a low voltage source of sensing current and throttle position and when things didn't jive it would activate some sort of mechanism that would break the battery pack feed. Electromechanical devices made for electric busses and trains and such use these as their safety switch so I can't imagine people not trusting them, but I can envision a spring loaded break operated by electromagnets that wasn't sitting in your lap.


Those kind of things are huge. Take a look at a 200 amp 3-way service disconnect on a house or a business. It has a spring loaded mechanism that takes lots of force to pull but unloads it very quickly to break contacts. That box is huge and would not likely fit in the trunk of your car ;-)


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## electrabishi (Mar 11, 2008)

maxvtol said:


> If I'm dodging shopping carts in a parking lot, I don't think I'll be able to find the OS bar.
> 
> And any amount of time over instant is way too long (thinking of Prius brakes here).


Prius brakes suck, although I can't imagine them not being able to slow a full on controller failure. That motor system must be stronger that what I had anticipated ;-) And you'd be surprised how quick you can pull an OS bar. If it is in just about the same position as the emergency brake lever in older manual transmission cars. How long does it take you to find the brake pedal in a new car?

Mike


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## electrabishi (Mar 11, 2008)

jackbauer said:


> I'm currently testing a software modification on my version of Paul Holmes controller. If the system sees the throttle at zero but significant current flow to the motor it opens the main contactor and locks out the controller. I'm also going to incorporate a brake light switch input. If the system sees brakes on but significant motor current flowing it cuts off power. I'll be using two series connected kilovac ev200 contactors for the cuttoff.
> 
> I have several reasons why i dont like the in cabin disconnects.


And I have exactly 1 reason why I like them ;-) When your life is at risk the probability of you pulling that bar is greater than any contraption you can think of to disconnect power by remote mechanisms. Don't underestimate the will and power of the human mind and body. I will agree that there are people that machines are smarter than. But I strive not to be one of them. I'm not saying that I can do it quicker than an automated system, but I would venture that I can do it more reliably, or will die trying.



Mike


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## electrabishi (Mar 11, 2008)

Woodsmith said:


> I'm thinking of a parking brake lever, linked to a steel rod through the firewall or tunnel (no cables to break), attached to one half of an Anderson connector. Pull on the lever and Anderson breaks connection. The lever and steel rod connection can be made to give any suitable mechanical advantage.
> 
> An insulating cover can also be made that will drop down, spring loaded guillotine style, that blocks the arcing between the two halves of the connector and prevents reconnection without some intervention.


Hey now that may be an idea  I have an emergency brake lever! and if a steel rod pushed a contact bar or fuse out of its socket I could deal with that. As long as all the securing hardware stayed on. A lose nut on a pull block will inherently cut power, or indicate a problem. A lose nut on a linkage would cut your ability to cut power. But I can see where a system like this could be made robust.


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## electrabishi (Mar 11, 2008)

JRP3 said:


> Unless your detonator fails.


And you guys are scared of putting your hand on a fuse pull block mounted in the cabin.

heh heh, 

The ejection seat would be fun to try a few times though. I like to test my safety's multiple times ;-)


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## Woodsmith (Jun 5, 2008)

electrabishi said:


> Hey now that may be an idea  I have an emergency brake lever! and if a steel rod pushed a contact bar or fuse out of its socket I could deal with that. As long as all the securing hardware stayed on. A lose nut on a pull block will inherently cut power, or indicate a problem. A lose nut on a linkage would cut your ability to cut power. But I can see where a system like this could be made robust.


This is the thing.

With a nice big mechanical lever working on a hefty rod or bar with sound connection points it is easy to visually inspect to see if it would work in an emergency.
No electronic, electrical or cable set up is as easy to visually inspect or work with.

Also a lever on a length of 2"x1/4" flat bar held with a 3/8" pin welded in place physically acting on a fuse link or Anderson connector is cheap and easy to make and does not rely on any electronic monitoring system.

It is a bit like the excape procedures on a train, break a bit of glass to get hold of the big hammer to smash a window with. Much more reliable then operating an emergency door control.


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## maxvtol (Nov 11, 2009)

electrabishi said:


> Prius brakes suck, although I can't imagine them not being able to slow a full on controller failure. That motor system must be stronger that what I had anticipated ;-)


Was talking about the 1 second delay after going over bumps, my point being people don't like not being able to stop immediately. 



electrabishi said:


> And you'd be surprised how quick you can pull an OS bar. If it is in just about the same position as the emergency brake lever in older manual transmission cars. How long does it take you to find the brake pedal in a new car?


I think to disconnect power after you've stopped is fine, and a great idea. But in 35 years of driving of driving I've never had to use the emergency brake to stop the car in an emergency, it's not something I practice. I'd be more likely to remember to step on the clutch, which is how I'm building mine.


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## JRP3 (Mar 7, 2008)

maxvtol said:


> I'd be more likely to remember to step on the clutch, which is how I'm building mine.


I still think using the clutch pedal for a disconnect has a high probability of unintended activation. You're conditioned to clutching at every shift, at some point you could mimic that action when shifting and disable the vehicle, as could someone else driving it. At the very least you might want to move the pedal or bend it far to the side so it's not in the normal clutch position.


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## maxvtol (Nov 11, 2009)

JRP3 said:


> I still think using the clutch pedal for a disconnect has a high probability of unintended activation.


Not for the electrical power disconnect, just mechanical disconnect.


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## JRP3 (Mar 7, 2008)

maxvtol said:


> Not for the electrical power disconnect, just mechanical disconnect.


Right, but either way pushing the pedal by mistake and disabling the vehicle seems rather likely.


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## maxvtol (Nov 11, 2009)

JRP3 said:


> Right, but either way pushing the pedal by mistake and disabling the vehicle seems rather likely.


As in normal use of the car, not a permanent disconnect of anything. Motor is still stuck running (although brief).


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## JRP3 (Mar 7, 2008)

Oh I get you, my mistake.


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## 2cycle (Jul 2, 2009)

electrabishi said:


> Please excuse me if I haven't read through the rest of this thread yet. But I'm going to go in order here.
> This is exactly what the Zilla does. When you are commanding 100% Throttle and 100 % duty cycle is achieved, every 0.01% of an on cycle the Zilla control board will tell the power section to turn of for a very brief period to see that the motor voltage actually goes to zero. If it fails this test then it will assume a full on failure and command the main contactor off. This is exactly what you are talking about. And this is what makes the Zilla controller such a safe unit. I'm not saying that it is full proof, however it is already built in. Pending that safety failing I put in the next most positive means of disconnecting the battery current from the controller. My hand puts a 6 inch air gap in the main power conductor. Maybe the majority of people, or maybe even no more people will ever put a pull block on their tranny tunnel, but if they ever fail full on they would wish they had.
> 
> Now back to my point. To get this safety in another controller you will need to do any or several of the procedures we are talking about. So since we are talking about those I can tell you in two separate cases where a Zilla has not actually failed full on, but the conditions existed where a Zilla controller did not shut down, one in the White Zombie where the accelerator pedal got stuck in the carpet (the Toyota failure) the pull block likely saved a life and a car. In the second (in my case on multiple times when many people saw it) through what I know now was a code problem in my controller, the Zilla actually thought it had failed full on and commanded a shut down of the main contactor under full throttle. Now you might think this is harsh on a contactor but the Zilla actually commanded the power section to turn off first, which it was able to accomplish because it hadn't actually failed, and then commanded the main contactor to open. So with wheels in the air and 1500 ft-lbs of torque on the driveline, the car shut down and rolled maybe another 20 feet.
> ...


What the Zilla uses sounds like the throttle override priciples we use. I didn't realize it had that feature, I guess I know what one to look at when my time comes. Why don't all controllers have it, all of the snowmobile manufacturers have to have some sort of throttle override. Seems if one can do it they all should. 
I have no doubt the manual pull block works well, I just believe there is a more automatic and less dramatic way of doing the same job for the "full on" type failure. 
When my EV gets to that point of the build it will have a mechanical safety disconnect of the driveline (clutch) so my application is a little different anyway, it may fail full on but a hydraulic line from the clutch master cyl to a breaker is my choice for mechanical but some EE friends of mine can build my throttle override to operate the disconnect for me if need be.


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## MJ Monterey (Aug 20, 2009)

A cautionary note, on the subject of using the E-brake to activate the "disconnect of last resort".

I drive in many hilly area and use my e-brake/handbrake allot to keep from rolling back at stop signs/lights. A habit I know a significant percentage of drivers in this area have developed (it was taught in school here). 

In my younger financially embarrassing years I drove a friends 65 Mustang across town with only the e-brake when a brake line failed. Yes people are this crazy and sometime dumb.

After reading through this thread, at this point, I will be looking at using a robust handle painted RED (designed along the lines of an early 60's Mustang e-brake handle). Maybe include a ratcheting mechanism also so that it can not accidentally re engage until the handle is rotated.

I should be able to mount 2 big blade switches (or some equivalent) on the battery rack so that I can completely isolate the pack by pulling on the lever in the cabin.


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## jackbauer (Jan 12, 2008)

What I believe needs to be done here are a few simple practical tests to show what works and what does not work. Lets get one of each of the contactors used in evs and open them under 500amps 200v conditions. Do that same with any device intended as an emergency disconnect. Then and only then will we know as a community what works safely and what makes plasma.

I had the throttle snag open a month or so ago during testing. Its a compound motor so no risk of overspeeding but it wound up like a gas turbine. My first reaction was to switch off the ignition. Pure instinct. Not hunt around for some rube goldberg contraption of bars and levers and ejector handles


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## Woodsmith (Jun 5, 2008)

MJ Monterey said:


> A cautionary note, on the subject of using the E-brake to activate the "disconnect of last resort".
> 
> I drive in many hilly area and use my e-brake/handbrake allot to keep from rolling back at stop signs/lights. A habit I know a significant percentage of drivers in this area have developed (it was taught in school here).
> 
> ...


I was thinking along the lines of a second e-brake/parking brake/hand brake lever mounted somewhere else in the cabin so it is not mistaken for the conventional brake. Maybe between the seat and the door or sideways infornt of the seat with a breakable strap to prevent accidental use when adjusting the seat, or an umbrella handle type under the dash where the normal brake is on the tunnel.

I agree with jack, all this talk is nought if the disconnect device isn't tested. Someone with the means to set up a test rig should try it and see what works and what doesn't before setting up electrical or mechanical actuators to operate them.


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## jackbauer (Jan 12, 2008)

I'm fully prepared to perform the tests. Just supply the parts. Here's what happens with a low voltage dc current of approx 180 amps :
http://www.youtube.com/watch?v=533A84oBBj8


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## JRP3 (Mar 7, 2008)

Rather uneventful when you moved quickly.


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## Woodsmith (Jun 5, 2008)

Good video there Jack. Thank you for posting it.



JRP3 said:


> Rather uneventful when you moved quickly.


The trick is to break quick and leave a large gap.

It would be interesting to see the arc if the gap left was the size you would have on an ac rated switch or contactor.

I guess it would make a good case for breaking a plug connection with a hefty pull rather then relying on an under rated switch or contactor. However, properly rated switching would be best.


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## JRP3 (Mar 7, 2008)

Woodsmith said:


> The trick is to break quick and leave a large gap.


Well yes, I think that's obvious. I got the impression Jack was trying to show something spectacular, and all he showed is what we already know, if you don't disconnect fast enough and far enough you'll get arcing.


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## dexion (Aug 22, 2009)

So where are we on this, all I can seem to find are big red buttons that are rated at 80V (my pack is 156V.) So unless I gang them up on a pair and open them in an emergency at the same time (so the amperage doesnt all go through the slower one to open and burn it up for a second) my choices are well none. I cant find anything that will kill 400 amps at 150V (my fuse will blow at 400 amps) but say im in a runaway situation and im only pulling 300 amps so my fuse wont help then like it would in a dead short. 

I was thinking of a big blade switch I could put a cable to, but I really havent found much there either. That anderson disconnect on the first page really doesnt look like it will handle the current. I have one the same size on my charger and it gets warm at 15 amps but thats just a seat of the pants feeling. I dont want to put a safety switch in that causes problems/is dangerous. 
dex


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## JRP3 (Mar 7, 2008)

Saw a variation on the knife switch idea that had a small wire or fuse that bridged the contacts which would provide momentary connection while the switch opened under load and allow a path for the current to travel. This would vaporize once the switch opened. Here's a quick sketch.


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## jackbauer (Jan 12, 2008)

JRP3 is right. I did expect something more spectacular. I'm actually pleased it wasnt that bad! I still maintain that we need experimental evidence. If funds allow i'll buy a big red button and an albright contactor and run that test. Every other part of an ev is tested. A video showing a disconnect opearting at 500amps 200vdc would let the seller name his price! I'd buy one. Safety has no price.


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## Roy Von Rogers (Mar 21, 2009)

It seems we are working on the wrong end of this problem. I too have visualized some kind of emergency disconnect in case of major failure of the system. My first idea was just a manual disconnect, something similar we use in the HVAC field, next to a piece of equipment, and of course rated for the voltages and amperages used in the ev field.

But after thinking this over a bit and being a promoter of the KISS princible, it occured to me we already have, or better have, a device that would give us a positive disconnect, the main fuse.

The only thing needed at this point would be a red T handle on the dash or other convienient place, to pull, and provide a death short to the the fuse. 

Roy


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## Jimdear2 (Oct 12, 2008)

jackbauer said:


> JRP3 is right. I did expect something more spectacular. I'm actually pleased it wasnt that bad! I still maintain that we need experimental evidence. If funds allow i'll buy a big red button and an albright contactor and run that test. Every other part of an ev is tested. A video showing a disconnect opearting at 500amps 200vdc would let the seller name his price! I'd buy one. Safety has no price.


Jack,

If you decide to try this on Albright equipment you might look at a SD300B combination contactor and disconnect with mag blowouts It's
i cheaper than a SW 200 with Mag blowouts and a separate ED series Disconnect. 

http://curtisinstruments.com/index.cfm?fuseaction=cdatasheets.dspListDS&CatID=7&siteID=1

Another point I don't know if the ED series Disconnects have Mag blowouts. 

I have been using the SD300B for a while now and am quite happy. My system is only 72 volts and 450 amps so I really can't give it a real test. After I get done replacing the batteries I'll go out and slap the switch while under a heavy load and see what happens. 

I'll let you know


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## Alexander_B (Oct 19, 2010)

Roy Von Rogers said:


> The only thing needed at this point would be a red T handle on the dash or other convienient place, to pull, and provide a death short to the the fuse.


I think this is an excellent idea, even if your emergency use-once 'contactor' would weld, it would end up in a safe state (killing the main fuse), unless its a proper contactor and the main fuse is a switching fuse, it takes some work with a spanner to get going again tho, unlike the connector-break setup. ah well, each has its advantages.. 

and for the anderson


dexion said:


> That anderson disconnect on the first page really doesnt look like it will handle the current.


well, anderson connectors exist in multiple sizes, not sure wich one you have, but they do go up to some pretty high ratings (200+A) but yes, you are right, it specifically states in the datasheet that they are not to be used to (dis-)connect large currents.


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## MalcolmB (Jun 10, 2008)

I've been using an Airpax circuit breaker on my motorbike for a couple of years now and I've just bought another for my car conversion: http://airpax.sensata.com/site/utilities/eliterature/pdfs/jae.pdf

Apart from acting as an emergency disconnect I also use the breaker to give complete pack isolation when I'm working on the bike, since it's in the opposite leg of the circuit to my main contactor.

You can often find these on ebay, and there are a few of the JTE versions on there now with 400A and 600A ratings.

On my bike I have the breaker connected to the original clutch cable, so I can trip it in an emergency by pulling the clutch lever. JRP makes a good point about unintentional tripping, and I've done that a few times, but only when stopped. On my bike it's easy enough to reach down and reset the breaker.

I also plan to use the clutch pedal to activate the breaker in my car. I may just mount it inside the transmission tunnel with the lever exposed so I can reset it manually from inside the car. If I place it under the hood I'll use the choke cable to reset it in case of accidental operation.

Not saying this is the ideal setup, but it works for me.


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## sailfish11 (Sep 15, 2007)

Here's what I've got in my car:










A cable can be added to allow it to be pulled from inside the cabin.


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## major (Apr 4, 2008)

electrabishi said:


> This is my solution to the pedal fail problem as well as a full on failure problem and welded contactor problem etc etc. http://www.thefoat.com/fa/m-photo/photo_id-6826/member_id-cp+ndsLnd2IM3ohQzYqz0w== We affectionately call it the "Oh Shit!" bar.


I wonder if Ronnie has one of these in his Camaro


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## dtbaker (Jan 5, 2008)

sailfish11 said:


> Here's what I've got in my car:
> A cable can be added to allow it to be pulled from inside the cabin.


you for sure want a cable pull from cabin! Good location is by drivers left knee so it COULD also be reached by Emergency person on outside. Choke Cable from JCWhitney works great and is cheap.

question: are those rubber boots covering cell buss bars? source? cost?


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## electrabishi (Mar 11, 2008)

dtbaker said:


> you for sure want a cable pull from cabin! Good location is by drivers left knee so it COULD also be reached by Emergency person on outside. Choke Cable from JCWhitney works great and is cheap.
> 
> question: are those rubber boots covering cell buss bars? source? cost?


We use the generic choke cable kit from Schmucks as the disconnect pull to the breaker handle on the Junior Dragster.

Mike


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