# Killswitch button



## cruisin (Jun 3, 2009)

Big K said:


> Hi
> 
> I know that people often put a killswitch somewhere in the cockpit of their car to cut all power in case of an emergency. I was wondering how to do this.
> 
> Thanks


You can either use a panic button to turn off the 12v to the controller/contactor and/or a hi-amp and hi-voltage button switch to disconnect the battery pack from the controller. There are various brands available at the EV dealers.


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## DIYguy (Sep 18, 2008)

I use remote shunt trip on my breaker.


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## lowcrawler (Jun 27, 2011)

cruisin said:


> You can either use a panic button to turn off the 12v to the controller/contactor and/or a hi-amp and hi-voltage button switch to disconnect the battery pack from the controller. There are various brands available at the EV dealers.


Is it enough to simply turn off the 12V power to the contactor? I mean, if something has gone wrong -- it could be welded tight, no?

Shouldn't the emergency disconnect be independent of anything that would 'normally' occur to the car?

I'm just starting to look into emergency disconnect and it seems to me that the 'normal' way of turning off the car (remove the 12V to the contactor) isn't a great idea for 'emergencies'... no?


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## mizlplix (May 1, 2011)

For the car to be completely "electrically" dead, you need to isolate and seperate the individual battery packs, from the circuit and from each other. 

A mechanical disconnect between the last battery and the controller is a must, another between the packs is desirable.

Armor the main cabling as well as possible and route through the center of the car as well.

Any disconnect needs to be colored RED. 

I have a Marine 850AMP mechanical switch. It is is only for 24VDC though. My plan is to only switch it under load once in an emergency. I have a 12" long "T" handle added to it so my hand is not anywhere near at the time......LOL

I am contemplating another one between packs. *(It is a good idea for a second one also because when working on the system, you can get into the high voltage circuit in the oddest places. I have several melted screwdrivers to attest to that.)

If you do all of the above, then all you need to worry about is shorting the battery posts in the packs, like dropping a tool in there....(Dont ask)

Miz


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## dtbaker (Jan 5, 2008)

you SHOULD have an inertia switch on your 12v power to contactor AND a mechanical pull on your main circuit breaker. Easy way to do this is to run a choke cable pull from the circuit breaker thru firewall, and mount the knob down by your left knee where you or emergency personnel could reach in the window, see it, and pull it.


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## ddmcse (Oct 9, 2008)

DIYguy said:


> I use remote shunt trip on my breaker.


could you elaborate on this setup ? I think my breaker is capable of doing this . it has some kind of shunt connection wire that i do not use on my hineyman (heinemann) breaker.

here is what i installed for a DMV passing switch 










Just the kind of stuff they want to see.

relatively worthless as it does the same thing as the key but it sure looks good to DMV


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## dtbaker (Jan 5, 2008)

mizlplix said:


> A mechanical disconnect between the last battery and the controller is a must, another between the packs is desirable.


or a big fat fuse mid-pack, or between packs.


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## fb88vnasia (Feb 21, 2019)

Big K said:


> Hi
> 
> I know that people often put a killswitch somewhere in the cockpit of their car to cut all power in case of an emergency. I was wondering how to do this.
> 
> Thanks


Same Question!


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## Frank (Dec 6, 2008)

Anderson makes a device that separates the two halves of it's connector when you pull a handle. I've seen that rigged up with a cable to operate it. 

Sent from my SM-T380 using Tapatalk


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## poprock (Apr 29, 2010)

Have all of the above plus fuel flap switch to prevent drive off when charging. Starting procedure is :- pack splitter on, main pack isolater on, 12v on ( old choke cable to 12v solenoid switch,) turn ignition to start for brake vacuum test, release key and zeva precharge powers system with audible click after 5 seconds, release handbrake, select 3rd gear and go. Setup is simpler with older cars. 1984 Subaru Sherpa.


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## dtbaker (Jan 5, 2008)

Frank said:


> Anderson makes a device that separates the two halves of it's connector when you pull a handle. I've seen that rigged up with a cable to operate it.
> 
> Sent from my SM-T380 using Tapatalk


pulling apart an Anderson under load is a BAD idea..... you'd get a MAJOR arc and possibly weld things together or blow apart the connector. Much safer to add a pull cable to your main disconnect circuit breaker which is designed to disconnect (a couple times) under load.

DIY EVs *should* have probably 3 or even 4 levels of disconnect to protect in various ways including the (rare) case of a controller or throttle getting stuck full on.

- clutched design of motor/transmission is prefferable to hard coupling
- main circuit breaker... with manual pull. A 'choke cable' can be run thru the firewall, and mount the pull next to the drivers knee
- low-voltage g-force interrupt of main contactor KSI voltage in case of accident, can be done easily for $20 with a fuel pump cutoff switch. Note that they *should* be mounted vertically
- additional big fat red 'kill' to interrupt key-on to main contactor on dash.... but this is really no different that turning the key off. The problem with a relay side kill is that it will not protect if the contactor welds itself together from arcing.

I have a couple pictures of all these things in my online build gallery at
http://envirokarma.org/ev/gallery
like this:
http://envirokarma.org/ev/gallery/110313_component_box.htm
shows the choke cable connected to main circuitbreaker, and the fuel pump disconnect (mounted wrong in this picture)


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## Frank (Dec 6, 2008)

All true but if the controller fails, it fails "on" and if the contactors don't open an "oh shit" switch could save the day.

Sent from my SM-T380 using Tapatalk


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## dtbaker (Jan 5, 2008)

Frank said:


> All true but if the controller fails, it fails "on" and if the contactors don't open an "oh shit" switch could save the day.
> 
> Sent from my SM-T380 using Tapatalk


exactly.

that's why I would advocate for at least THREE types of protection in DIY projects where things can and do go wrong.
1. key switch
2. inertia switch interrupting key switch (12v relay side of contactor)
3. manual pull to main disconnect circuit breaker (HV battery side)
4. clutched transmission

My problem with disconnecting Anderson plugs is that unless you have it in a spring loaded box to make a quick disconnect with a big gap it is not nearly as safe as a manual cable pull running to your main disconnect circuit breaker. You *should* have a big circuit breaker as a main disconnect for the battery pack regardless, and running a cable manual pull is cheap and easy.


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## Frank (Dec 6, 2008)

Do you have a source for high voltage, high current breakers ? 

Sent from my SM-T380 using Tapatalk


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## dtbaker (Jan 5, 2008)

Frank said:


> Do you have a source for high voltage, high current breakers ?
> 
> Sent from my SM-T380 using Tapatalk


ebay..... make sure they are DC rated as they need to open wider than AC as DC arcs are much longer. You can go with one, or tandem them if you plan to pull lots of juice for extended periods.

do a search on GJ1 B3 Du0250 01C
this is a decent single-pole one to use for our purposes.... 250amp, 125vDC, delay=1

Or, I can pull the one out of my eSwift I'm scrapping.... Its a GE dual pole 200amp. Let me know (direct email) if you need any/all of the components I have shown here:
http://envirokarma.org/ev/gallery/090301_final_assy00a.htm


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