# Run away EV



## Guest (Nov 23, 2009)

The subject of full on controller failures has come up every now and then. A big worry for most of us. I have about 4 pounds of failsafe systems in my car. But I still worry what if the contactors welded shut? What are the odds of this happening?


----------



## racunniff (Jan 14, 2009)

I don't know the odds of a runaway, but it is frequently listed as one of the advantages of keeping a transmission.


----------



## Woodsmith (Jun 5, 2008)

You a big cut out switch like this.











I don't know the odds of it happening but a big DC breaker somewhere in reach would be a good investment I think. It would save blowing the motor if there is time to use it rather then declutching. Declutching always sounds like a last resort that spells 'self distruct'.


----------



## Guest (Nov 23, 2009)

I have a friend that worked for Duke Power in N. C. Maybe he can get me one of those. Any one else want on the waiting list?


----------



## Guest (Nov 23, 2009)

PS. I had a curtis go about 9 years ago. I was still new to ev's so it had the controler right behind the drivers seat. Luckly I lived and learned. Anyway I can't remember slaping it in neutral but I was out and on the pavement fast. Second luck was it happened in my drive way. Lots more details than any of you want to hear. Third luck was I have over speed control so as soon as I collected my wits I hade time to climb back in and shut it down. Whats it like you ask? BIG BOOM!!! Lots and lots of smoke.


----------



## neanderthal (Jul 24, 2008)

Mine did on my first run with my old logisystems controller. scary. If I hadn't installed the kill switch my car and my neighbor's house would have been very badly damaged. So yeah it can happen. Although mine is not a good example because almost all of the first generation of the newer high voltage logisystems controllers blew up within the first few miles.


----------



## Thaniel (May 25, 2008)

I kept the clutch and think it is a wonderful feature if this ever happens. Yah the motor might bite it but odds of someone driving having enough sense about them to find a kill switch is low (I'll include myself).


----------



## jockepocke (Nov 24, 2009)

You will always have your brakes to stop you! 

My volvo 440 will be equipped with a dc breaker (500 A) that i got cheap. Will be somewhere close and see-able! It is big, so you won't miss it!


----------



## Guest (Nov 24, 2009)

So back to the contactor. I am thinking about the only way it could weld shut is if there was enough air gap for ark to happen. If it is good shape with a tight fit this should not happen. Anyone have some experience with this or know of someone who did? A clutch is a good safty. Usualy in an emergency the break and or clutch foot is the first thing to respond.


----------



## Woodsmith (Jun 5, 2008)

Thaniel said:


> I kept the clutch and think it is a wonderful feature if this ever happens. Yah the motor might bite it but odds of someone driving having enough sense about them to find a kill switch is low (I'll include myself).


You could put a big red stop button on the dash or the centre console somewhere.
This is the one on the Kickngas MR2.









I am more tempted to put it on the gear stick in a Mad Max style!









I think, though, My MR2 would need to look more like this one!


----------



## EV-propulsion.com (Jun 1, 2009)

Nice Cars!
anyhow, if your throttle stuck on your ICE, what would you do? Where is the kill button on that? I say turn off the ignition- you do have an ignition key right? Usual systems have two contactors, at least one should open with the key turned off, right?
Or, stand on the brakes and let the fuse blow-you do have a correctly sized fuse right?
I found that many people consider an EV dangerous if you need a seperate kill switch in the middle of the dash........
Mike
www.EV-propulsion.com


----------



## Woodsmith (Jun 5, 2008)

That's very true about the ignition key. However I think the problem could be more a case of a contacter being just a little too closely rated and welding shut maybe and in that case having more then one in line might help.

I have been in a diesel Land Rover that wouldn't switch off. The engine was sucking in its own engine oil and the clutch was a little too worn out to stall it. A halon fire extinguisher in the air inlet eventually stopped it. Didn't spray it in, just used it to bung the air pipe!


----------



## Guest (Nov 24, 2009)

Don’t laugh but I have a wire running to the seatbelt warning switch to the emergency break warning switch to the key switch and then the nobody knows where its at but me switch (and the breaks are in top condition. )So the contactors will not engage unless I am sitting in the car with the emergency break off the key switch and the secret switch on. Plus fuses up the wazoo. How’s that for redundancy? But my ulcer needs that constant drip drip so I have to have something to worry about.


----------



## dtbaker (Jan 5, 2008)

I had my throttle cable fray and stick open once.... thank god for the manual pull on the main circuit breaker! In this case the key would have worked too, but I am a believer in all three: key, manual pull, and an inertia switch.


----------



## squatch81 (Nov 9, 2009)

I have yet to build my 1'st EV, so please take my advice with a grain of salt.
I do, however, have over 20 years in the overhead crane industry - most of them as service tech.
When browsing the offerings of a couple of component suppliers here, I was disappointed with their selection of contactors suitable for emergency disconnect.
Breaking a HVDC circuit under any appreciable current creates a large arc, and the high inductance of a motor load exasperates the problem. I have seen double break contacts flash over for several seconds after opening with only a moderate load. This is usually compensated for by putting several sets of contacts in series with the load - increasing the total air gap.
When I build my EV, there will be at least 2 (if not 3) sets of contacts in series with the traction battery, controlled by a large red mushroom head switch mounted within easy reach.
As great as the safety liability in my industry is, I can't imagine treating the liability of driving a "home brew" modified vehicle on public roads with any less due diligence.


----------



## elevatorguy (Jul 26, 2007)

notmrwizard said:


> The subject of full on controller failures has come up every now and then. A big worry for most of us. I have about 4 pounds of failsafe systems in my car. But I still worry what if the contactors welded shut? What are the odds of this happening?


I would use some kind of power disconnect, either a shunt trip (pricey) or a mechanical means of disconnecting the batteries.
There is a good possibility of contact welding or arc over at high load that would keep current flowing.
I have contactors, fuse, circuit breaker, and cable operated disconnect. I hope I never use them, but cheap insurance.
my 2 cents...


----------



## Electric Car-Nut (Jul 5, 2009)

Several EVs I have looked thru included an "Anderson Connector" with one part bolted to the fender well under the hood on the driver's side and a piece of 1/8 inch aircraft cable looped through the insulated portion of the other half of the "Anderson Connector" and clamped to itself to make a loop, then routed thru a drilled hole in the firewall then thru a hole in the dash to a big red knob in very easy reach of the driver. "Just pull for emergency stop." very reliable ! Sort of like the Kill pull for a diesel. You know it is going to stop for you...


----------



## Gene (Apr 8, 2009)

I'm using a forklift battery plug as a last resort emergency disconnect on my quad conversion, simple and very effective.


----------



## dataman19 (Oct 7, 2009)

Hi gang.. Nice thread...
jockepocket - Brakes? To stop you from a run away? Think about this. I don't agree (and don't take me as the ultimate expert - just hear me out..)
..
In a controller failure , assuming the controlled fails dead on and full power to the wheels - the brakes are not gonna stop you. If you have your foot down hard on the brake and are at a dead stop when this happens - maybe the brakes will give you a little brain spurt time.. But the car is gonna run away. Face it... In my drag racing days I cannot tell you how many people used to say that good brakes will always stop you. Then their Nitro Meth powered fire breathing monster goes bonkers and full on - they take the fence at the end of the track and make a spectacular and crowd pleasing standing screaming in the bleachers grand finale...
...
notmrwizard - Arc is when the contacts open under load. If you are lucky you won't get a plasma ball (electrical plasma fire). No air gap is going to totally eliminate the arc potential (but will definately minimize the detrimental effects). The idea that Squatch81 had of multiple contactors in series sounds like a very reliable prevetative measure. But multiple contactors give multiple potential points of component failure too.
..
But since most arc issues are when applying the initial load, I tend to agree with the general consensus that a good pre charge circuit to minimizethe potential of the closing contacts is the better remedy.
..
But I definately would not rule out the inclusion of an emergency disconnect.
..
But think about this. An arcing contactor is nothing short of an arc welder. As the arc progresses the distance between the points widens as the material is burned off. Don't think that this will necessarily lead to an end to the arc - no sir. Once the arc burn is initiated in a high current circuit the arc progresses to a plasma arc. This is commonly called a plasma fire and it will consume everything metallic and combustible until the current dies down substantially (in other words - until the batterys go to neutral, zero).
..
Plasma fires are so intense they can literally blind you (evem more so than looking at a simple arc welder). They also generate enormous heat and then when the electrical energy dies - the fire ball continues having reached the flash point of most metals and combustibles.
...
Fire extinguishers do not etinguish plasma fires - foam helps. But even foam can sometimes just barely contain them.
...
But I digress - the thread is Full-On failure.
..
Something eveyone needs to plan for, and hope they don't experience soon, or often.
..
Been there, done that - NO FUN - No FUN AT ALL!!! I was saved by a 4 foot thick bunker wall, thank god I only traveled 15 feet (any longer and I would be called accordian man instead of dataman...
..
Just my 1.5 cents worth gang..
Dataman19
..
Dataman19


----------



## jackbauer (Jan 12, 2008)

Interesting thread. I'm using a kilovac ev200 main contactor which is supposed to break 2.5ka at 320vdc. I'd still like a manual disconnect but cannot find anything suitable so far.


----------



## Guest (Nov 24, 2009)

Thanks dataman. I am going to reread your comments over a few times to get everything I can out of it. No Joke! Thanks again my ulcer is in heaven right now.


----------



## Guest (Nov 24, 2009)

Dataman Gene's battery plug should stop the type of arking you are talking about. Yes? We are going to have to start encrypting this stuff. If someone like Nader gets hold of this they will shut us down.


----------



## Guest (Nov 24, 2009)

One more thing Dataman mentioned a prechager. For anyone that has not read it I say do so now. It is very inforative. See Tec Discussion Ev high voltage turn it on and off.


----------



## dtbaker (Jan 5, 2008)

...just wanted to re-iterate that the inertia switch (from fuel pump power circuits) is a small inexpensive addition that I think is a great idea in case of accident where you may not be able to manually do anything. I got mine as part of standard kit from KTA, but I guess they are easy to find in salvage yards, especially on more Ford products, usually in the trunk in a wheel well near the fuel tank.


----------



## Guest (Nov 24, 2009)

Oh yeah I forgot to mention I have one of those too.


----------



## Dave Koller (Nov 15, 2008)

jackbauer said:


> Interesting thread. I'm using a kilovac ev200 main contactor which is supposed to break 2.5ka at 320vdc. I'd still like a manual disconnect but cannot find anything suitable so far.


http://www.diyelectriccar.com/forums/showthread.php/u-s-source-250-amp-disconnecti-38651.html

guys are trying to find those: 

personally I think one can be made ..


----------



## EV-propulsion.com (Jun 1, 2009)

We have a very similiar thread going on here that might be of interest:
http://www.diyelectriccar.com/forums/showthread.php/u-s-source-250-amp-disconnecti-38651.html

Mike
EV-propulsion.com


----------



## EV-propulsion.com (Jun 1, 2009)

Ooops, sorry Dave, you beat me to it !


----------



## dtbaker (Jan 5, 2008)

the airpax are good manual circuit breakers... higher amp limit than the mushrooms, but more expensive:
http://store.kta-ev.com/Circuit_Breakers_Fuses_Safety_Switches/Airpax_250Amps.aspx


----------



## Dave Koller (Nov 15, 2008)

EV-propulsion.com said:


> Ooops, sorry Dave, you beat me to it !


Same thought lol


----------



## Dave Koller (Nov 15, 2008)

dtbaker said:


> the airpax are good manual circuit breakers... higher amp limit than the mushrooms, but more expensive:
> http://store.kta-ev.com/Circuit_Breakers_Fuses_Safety_Switches/Airpax_250Amps.aspx


will they blow on a good "pedal stomp" ? I have been Leary of them inline for that reason!


----------

