# Re: [EVDL] run away [ accelerator pedal ] - crowbar circuit



## EVDL List (Jul 27, 2007)

*Re: [EVDL] run away [ accelerator pedal ] - crowbar circuit*

I think I may institute a simpler version of this. I have a spare
contactor rated high enough to blow my main fuse. Why not just use
that to short the pack right after the fuse? Who cares what happens to
it, you are trying to avoid disaster and these parts are expendable.
The contactor will make a circuit between the negative pack cable and
the positive side right after the fuse, which is the first component
on the positive pack cable.

I have a big red normally open button that latches on when pushed
(just in case it takes a second for the fuse to blow.) It will close
the contactor and keep it closed. It will only be hot when the
ignition is on.

And I'm not going to worry about powering it. If I don't have 12 volts
for the contactor, something else really bad has already happened.

The only tricky part is protecting the switch from unintended poking.
If you press the button, you have to change the fuse. A "Break Glass
And Push Button" case might be a little too much. I'll have to make it
angry looking so nobody will be tempted to push it unless they really
need to.

Dave Cover



> gary <[email protected]> wrote:
> > I wanted to change the subject for any further discussion. Sounds like
> > a good idea Victor. Everybody should have the fuses installed anyway so
> > this might be cheapest and most reliable. Also cleaner for the
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] run away [ accelerator pedal ] - crowbar circuit*



> gary wrote:
> 
> > Now the question is how to fire the SCR - independent of house power
> > in
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] run away [ accelerator pedal ] - crowbar circuit*



> dave cover wrote:
> 
> > The only tricky part is protecting the switch from unintended poking.
> > If you press the button, you have to change the fuse. A "Break Glass
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] run away [ accelerator pedal ] - crowbar circuit*



> dave cover <[email protected]> wrote:
> > I think I may institute a simpler version of this. I have a spare
> > contactor rated high enough to blow my main fuse. Why not just use
> > that to short the pack right after the fuse? Who cares what happens to
> ...


----------



## EVDL List (Jul 27, 2007)

*Re: [EVDL] run away [ accelerator pedal ] - crowbar circuit*



> dave cover wrote:
> > I think I may institute a simpler version of this. I have a spare
> > contactor rated high enough to blow my main fuse. Why not just use
> > that to short the pack right after the fuse?
> ...


----------



## EVDL List (Jul 27, 2007)

*Re: [EVDL] run away [ accelerator pedal ] - crowbar circuit*



> Evan Tuer wrote:
> > That's going to be hilarious when you (or someone else) first replaces
> > the fuse after a nuisance trip and find out that it was actually
> > crowbarred and now the contactor is welded closed!
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] run away [ accelerator pedal ] - crowbar circuit*



> Roger Heuckeroth wrote:
> gary wrote:
> >> Now the question is how to fire the SCR - independent of house power
> >> in case that got fried in the emergency situation?
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] run away [ accelerator pedal ] - crowbar circuit*



> Lee Hart <[email protected]> wrote:
> > Evan Tuer wrote:
> >> That's going to be hilarious when you (or someone else) first replaces
> >> the fuse after a nuisance trip and find out that it was actually
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] run away [ accelerator pedal ] - crowbar circuit*

Evan Tuer wrote:
>


> Lee Hart <[email protected]> wrote:
> >> Evan Tuer wrote:
> >>> That's going to be hilarious when you (or someone else) first replaces
> >>> the fuse after a nuisance trip and find out that it was actually
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] run away [ accelerator pedal ] - crowbar circuit*

Victor may of come in late on this thread, Crowbar was one of the early
suggestions.

A question:
Doesn't an SCR default to open? it needs an active signal to turn it
on.(and then it is on until removed or reversed)
Do they make large gate shutoff thyristors (GTO) for a reasonable
price? Even a GTO defaults to off and requires an active signal to turn
it on or off.

I think I said two contactors, one across the pack downstream of
main contactor and pack fuse.
The crowbar contactor is nc the same power that energizes the main
energizes the crowbar breaking the potential short.
An aux switch mounted on the crowbar contactor would be great to
keep from having any overlap.
Otherwise "key on" opens crowbar and then "key start" energizes main
(or throttle of switch?)

In normal operation, you would never know it is there, but hit the
magic kill or turn off the key and force the fuse to blow.

Lee had a very good point about fuse sizeing. I have a book you can
get at any electrical supply house and they have curves for the fuses.
I have a 400A semi-conductor fuse and a 1000A zilla on a 288V pack
on a 4050 lb pulled by a 9". I have pulled 950A once. Still the original
fuse. ( I bought a spare 5+ years ago when I got the zilla. LOL )

I am trying to make sure that if a problem ccomes from the 12V side, say
pack leak onto 12V or 12V hits 6.5 and relay begins to drop out,
chatters and welds, that we can still stop the thing. If it takes the
12V to 5V supply to fire the SCR and the supply has also shut down
because of low 12V, wouldn't we still be screwed?

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## EVDL List (Jul 27, 2007)

*Re: [EVDL] run away [ accelerator pedal ] - crowbar circuit*



> Jeff Shanab wrote:
> > Doesn't an SCR default to open? it needs an active signal to turn it
> > on.(and then it is on until removed or reversed)
> 
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] run away [ accelerator pedal ] - crowbar circuit*

The only comment I have about using an SCR to crowbar the circuit is that an
SCR needs power to fire, and if there is a failure that interferes with that
SCR signal, then you've lost your crowbar. A mechanical crowbar has beauty
in its simplicity.


-- 
View this message in context: http://n4.nabble.com/run-away-gtas-peddel-tp1569843p1577534.html
Sent from the Electric Vehicle Discussion List mailing list archive at Nabble.com.

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## EVDL List (Jul 27, 2007)

*Re: [EVDL] run away [ accelerator pedal ] - crowbar circuit*

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## EVDL List (Jul 27, 2007)

*Re: [EVDL] run away [ accelerator pedal ] - crowbar circuit*

I understand, but simple is devine, especially in this circumstance. If I
were to design such a circuit, I would put a fail-safe indicator that would
at least tell me my firing circuit had power, and still assume the SCR was
still functional.

But, how can you beat a simple knife-blade switch with a rope into the
cabin?

That's all I mean. Electronics are cool... when they work. It's really
hard to make them failsafe absolutely.




> Ben-149 wrote:
> >
> >
> > I'm liking the simple assurance that this will absolutely kill power
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] run away [ accelerator pedal ] - crowbar circuit*



> mark at evie-systems wrote:
> 
> >
> > The only comment I have about using an SCR to crowbar the circuit
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] run away [ accelerator pedal ] - crowbar circuit*

Blasphemy to even suggest the same ;-)



> > Doug Weathers wrote:
> >
> > It's a poor bet to assume that a Lee Hart solution is fundamentally
> > flawed
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] run away [ accelerator pedal ] - crowbar circuit*

Here's my emergency shutoff... a 250A 125VDC circuit breaker (commonly used
for solar inverters, but the 125VDC rating is good for a 96 volt battery
bank). A red pushbutton on the dashboard where the choke used to be pushes
on the handle of the breaker and trips it. For those using lower power 96
volt systems, it's pretty slick, I think. About $150 for the breaker.

Z



>
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## EVDL List (Jul 27, 2007)

*Re: [EVDL] run away [ accelerator pedal ] - crowbar circuit*



> Zeke Yewdall wrote:
> 
> > Here's my emergency shutoff... a 250A 125VDC circuit breaker
> > (commonly used for solar inverters, but the 125VDC rating is
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] run away [ accelerator pedal ] - crowbar circuit*

Please accept my sincere apology for my statements.




> Mike Willmon wrote:
> >
> > Blasphemy to even suggest the same ;-)
> >
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] run away [ accelerator pedal ] - crowbar circuit*



> Mike Willmon wrote:
> > Blasphemy to even suggest the same ;-)
> 
> Doug Weathers wrote:
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] run away [ accelerator pedal ] - crowbar circuit*

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## EVDL List (Jul 27, 2007)

*Re: [EVDL] run away [ accelerator pedal ] - crowbar circuit*



> >Mark wrote:
> >
> > But, how can you beat a simple knife-blade switch with a rope into the
> > cabin?
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] run away [ accelerator pedal ] - crowbar circuit*

I also use a version of this design.
My truck came with a manual choke cable that I replaced with a beefier
one from a speed shop.
Routed it to the breakers under the hood.

I would recommended a choke cable, even if your car is not equipped with
one. 
You only have to drill ~ 3/8" hole in your dash to mount it.
The cable has a braided cover that is flexible and can be routed very
easily.
The only drawback is you will have to reset the breakers manually, since
the cable will not push it back into position.
Since it would only be used in an emergency situation, to me this is a
minor inconvenience.


If anyone would like pictures of this installation, contact me off line.


Thanks;
Dennis 
Elsberry, MO 
http://www.evalbum.com/1366 






> -----Original Message-----
> From: Zeke Yewdall [mailto:[email protected]] 
> Sent: Wednesday, March 03, 2010 10:06 PM
> To: Electric Vehicle Discussion List
> Subject: Re: [EVDL] run away [ accelerator pedal ] - crowbar circuit

> Here's my emergency shutoff... a 250A 125VDC circuit breaker (commonly
used for solar inverters, but the 125VDC rating is good for a 96 > >
volt battery bank). A red pushbutton on the dashboard where the choke
used to be pushes on the handle of the breaker and trips it. For >
those using lower power 96 volt systems, it's pretty slick, I think.
About $150 for the breaker.

> Z



>
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## EVDL List (Jul 27, 2007)

*Re: [EVDL] run away [ accelerator pedal ] - crowbar circuit*



> dave cover wrote:
> > Wow, if you think about this too much you'll end up sitting in a dark corner
> > afraid to come out.
> 
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] run away [ accelerator pedal ] - crowbar circuit*



> Lee Hart wrote:
> 
> > If you want to experiment, or are broke (or an incurable cheapskate)
> > you
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] run away [ accelerator pedal ] - crowbar circuit*



> Roger Stockton wrote:
> > Zeke Yewdall wrote:
> >
> >
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] run away [ accelerator pedal ] - crowbar circuit*



> On 3 Mar 2010 at 21:13, Roger Stockton wrote:
> 
> > the breaker handle sticks up through the floor beneath the handle of
> > the parking brake where it is protected from accidental knocks but is
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] run away [ accelerator pedal ] - crowbar circuit*



> Peter wrote:
> >Thanks for the inspiring discussion...
> 
> I've been enjoying these threads, too--though when I look at my email these
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] run away [ accelerator pedal ] - crowbar circuit*



> EVDL Administrator wrote:
> 
> > On 3 Mar 2010 at 21:13, Roger Stockton wrote:
> >
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] run away [ accelerator pedal ] - crowbar circuit*



> On 4 Mar 2010 at 12:39, Roger Stockton wrote:
> 
> > APM Hexseal offers boots to fit the 1, 2, and 3 pole GJ1 Heinemann breakers (I
> > use a single-pole GJ1 in my EV):
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] run away [ accelerator pedal ] - crowbar circuit*



> James Massey wrote:
> 
> > G'day Roger, All
> >
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] run away [ accelerator pedal ] - crowbar circuit*

G'day Roger, All

At 02:18 AM 6/03/2010, Roger wrote:
>


> James Massey wrote:
> > > G'day Roger, All
> > ><snip>
> > > Not from Ebay, but that is exactly what I'm putting in my Honda, the
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] run away [ accelerator pedal ] - crowbar circuit*



> James Massey wrote:
> 
> > G'day Roger, All
> >
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] run away [ accelerator pedal ] - crowbar circuit*



> Roger Heuckeroth wrote:
> > I would argue that an electrical disconnect could be more reliable
> > than a mechanical one depending upon the configuration. In an
> > accident your mechanical linkage may get damaged. Especially, if
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] run away [ accelerator pedal ] - crowbar circuit*

But we were talking about ways to stop a full on failure and runaway condition in progress. Presumably if you have already crashed
then the problem has been mitigated. I would never argue that an inertial switch be used to shut down the car by intentionally
running into something so that the shut down occurs. Isolation for safety reasons after a crash is a different discussion.

;-)

Mike

> -----Original Message-----
> From: [email protected] [mailto:[email protected]] On Behalf Of Rick Beebe
> Sent: Saturday, March 06, 2010 7:08 AM
> To: Electric Vehicle Discussion List
> Subject: Re: [EVDL] run away [ accelerator pedal ] - crowbar circuit
> 


> > Roger Heuckeroth wrote:
> > > I would argue that an electrical disconnect could be more reliable
> > > than a mechanical one depending upon the configuration. In an
> > > accident your mechanical linkage may get damaged. Especially, if
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] run away [ accelerator pedal ] - crowbar circuit*

That's why I suggested putting the panic (emergency disconnect) button 
and the inertia switch in an OR circuit where either one of them would 
shut of the main breaker.

Someone mentioned the failure of the 12V system. I'm thinking of 
charging a large cap through a diode and resistor to essentially have 
a circuit that would stay active even if the 12V chassis system went 
down.



> Mike Willmon wrote:
> 
> > But we were talking about ways to stop a full on failure and runaway
> > condition in progress. Presumably if you have already crashed
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] run away [ accelerator pedal ] - crowbar circuit*

I actually had this thought about an inertia type switch mounted on the dashboard of the Pinto. It would be a 9V transistor battery
mounted in a holder on the dash. You know how those press on tabs are not that strong in a twisting direction. Anyway the 9V
battery would stand upright, upside down mounted on the holder. If you smack something the battery flies off the base (probably
breaking your windshield ;-( but the voltage removed from some latching circuit would cut the main power from the pack. I would
get back into the pits and tell everyone my battery died and I have to put in a new one. Of course they don't know it's the
emergency disconnect battery. They just see that when I put a new Energizer in the car it goes fast again ;-)

Mike

> -----Original Message-----
> From: [email protected] [mailto:[email protected]] On Behalf Of Roger Heuckeroth
> Sent: Sunday, March 07, 2010 8:48 AM
> To: Electric Vehicle Discussion List
> Subject: Re: [EVDL] run away [ accelerator pedal ] - crowbar circuit
> 
> That's why I suggested putting the panic (emergency disconnect) button
> and the inertia switch in an OR circuit where either one of them would
> shut of the main breaker.
> 
> Someone mentioned the failure of the 12V system. I'm thinking of
> charging a large cap through a diode and resistor to essentially have
> a circuit that would stay active even if the 12V chassis system went
> down.
> 
>


> Mike Willmon wrote:
> >
> > > But we were talking about ways to stop a full on failure and runaway
> > > condition in progress. Presumably if you have already crashed
> ...


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