# Battery cut off switch for emergencies



## Roy Von Rogers (Mar 21, 2009)

HighTech said:


> Having had a few episodes myself with a rug bundled up under the pedal and others just having an older pot box freak out on them, I decided to bring up this topic. At night you still wants lights so you can see where you are going, so shutting off the vehicle completely was not making sense. Now, having a cut off switch from the main battery pack was a little out of reach and unfeasible (since again I wanted lights), so instead putting a cut off switch from the lead wires going to the pot box was much better. In this fashion, the power cable going to the pot box is cut, thus the two wires were extended going inside the vehicle to a switch, when the switch is up it is on, when down it is off thus no power will go to the pot box and can be an effective way to cut power to the electric motor if such an emergency happens. I still have my lights and everything else working in the car, just the motor is not going at full speed down the road.
> 
> Example:
> Now when I am going down the road and I know I don't have cruise control and the car doesn't slow down when I lift my foot, something was not right. I wanted power to all my other components in the vehicle including lights at night, so just adding in a switch to cut off the power to the pot box was making more sense.
> ...


I dont understand why this is such a problem. First of all, all EV's should have a BRB switch (Big Red Button) available on the drivers side, if yours doesnt, your playing russian roulette. Also your lights should run off your accessory battery, if you dont have one, put one in.

Pushing the BRB in an emergency will not affect your lights if you do the above.
Its not a High Tech solution, but it works (pun intended)

Roy


----------



## JRP3 (Mar 7, 2008)

You can also just wire it so the kill switch cuts power to the controller but the DC/DC is still wired to the pack, that's how mine is setup.


----------



## Guest (Oct 22, 2010)

In an emergency you want to kill the power to the HV pack and not the pot or controller. You can still keep power to your accessories if you connect low amp connections to your DC DC converter. You don't need to have that one cut off if you cut main power to the contactor. That is where you should break it. Just before or after your contactor. If you break it in the middle of the pack then you take the chance to cut power to your DC DC. 

Think about how you need your power but you must connect your BIG RED to the main and not the accessory.


----------



## JRP3 (Mar 7, 2008)

Not sure what you mean. If you have a full on controller you certainly want to cut the power going to it.


----------



## Guest (Oct 22, 2010)

I am just trying to be clear on the power that needs cut. Controllers also use low power as well to activate things. So just saying cut the power to the controller could mean your referring to the low power side that controls the pot and all that other junk. If I cut power to that then I could still be in big trouble with a welded switch. So power that needs cut is the HV power that powers the controller and motor. Not the low voltage that controls the pot and LV side of the controller. 

That's all. 

But if you have your DC DC connected to your pack you can cut your pack power at the contactor and still have power to your DC DC for keeping your accessories going if needed. If you cut your power in the middle of the pack you loose your DC DC too. 

Pete


----------



## JRP3 (Mar 7, 2008)

Depends on the controller and setup I guess. Neither my Alltrax or Curtis have low power going into them, all power comes from pack voltage. I take it your Kelly has a different setup?


----------



## Guest (Oct 22, 2010)

Yes and so was my old Golf Tech Controller. Plenty of good old stuff being used. I just use DC power to the controllers where needed. My Synkro takes its power from the pack too. But I won't cut power to the pot. Only to the HV side near the contactor so I can keep my DC power active. I think that is what is needed. Not all power needs cut. If all power gets cut I just shut off my circuit breaker which cuts off all power even to the DC DC. Just clarifying for those who have external power to the controller for the accessory stuff. I think all controllers should provide that from within but alas not all do. Most new ones do so it does not apply to those folks. 

Pete


----------



## DIYguy (Sep 18, 2008)

yes, I also cut main power via a red mushroom connected to a remote shunt trip on my main breaker. All accessory power is maintained through the 12 volt acc battery. Even power brakes stay power!  Someday, I might have power steering....that will also stay powered . (even the ICE's don't normally do that... .well maybe the ones with Elec/hyd do....


----------



## dtbaker (Jan 5, 2008)

JRP3 said:


> You can also just wire it so the kill switch cuts power to the controller but the DC/DC is still wired to the pack, that's how mine is setup.


mine too.
the dc-dc takes power off the pack BEFORE the big circuit breaker w/ kill pull, so I would retain all 12v systems (lights, horn, air bag) even after kill. There is enough vacuum for 2 or three 'braking events' without power, so that's not a worry either.

motor and controller are downstream of mechanical kill...

d


----------

