Where to put the KILL switch

[swbluto]

Just thought I'd explore the topic of positioning the kill switch. In the situation where your controller decides to go full throttle, because the throttle got unplugged or whatever, where would the best place to put the kill switch be? I've heard that unplugging the battery could kill the ESC due to the voltage spike caused by the motor's inductance so I guess unplugging the motor sounds like the other option by default. But would unplugging one motor wire work with an ordinary one wire switch? Or would something like a three-pole on/off switch be needed so you could unplug the motor in its entirety?

Any ideas on a good way/place to wire the kill switch?


Anyways, I've unplugged the motor's wires a few times during initial testing during the run-aways and it didn't seem to cause the controller harm and it worked, but I don't know if it's as effective during higher current loads like say if you had a bike capable of 50 mph but you're in a situation where 20-30 mph is safe and cutting out the wire at 35 mph might have a lot of current flowing if the controller goes full throttle.

 

[deecanio]

hi Sw,

mine is on my left thumb as per a motorcycle kill, easy to hit but more importantly i would like know what the best thing is to kill? if your connected to the controller/ebrake as far as i'm aware it only protects from full throttle? this time around im hoping to hook it up via dc/dc convertor and relay to actuall kill the power to the esc from the pack itself, a more reliable form of kill?


D

 

[Drunkskunk]

I have the battery wire were I can yank it out. on a BLDC controller, the only way for a runaway condition is if something goes realy wrong with either the throttle, or the trottle side input on the controller. it would take some bizzare circunstances for most setups to fail like that. if it was the conrtroller failing, then anything short of total power loss might not stop it.

There is a chance of blowing the controller this way, but its the safest, most positive way to kill the motor in all failure modes. and there's only a slim chance that i would ever need it.

If I should ever need to kill the motor in an emergancy, then screw the controller, I want to live!

 

[swbluto]

If I should ever need to kill the motor in an emergancy, then screw the controller, I want to live!

But what if there was an option for both you and the controller to live? I think there has to be some possibility to kill the controller/motor in the WORST case scenario without actually killing expensive electronics. I think yanking the motor wires out might work but I can see why it wouldn't work. (The motor would still have a voltage spike (right?) and that might arc across to the controller's motor wires) So I'm just trying to find some way to ensure everything's safe.

 

[RWP]

I agree with D & Drunkskunk above.

Currently with the Cortina because I went from 36v to 18v and my contactor was designed for 36 I have no contactor in the circuit. But as soon as I settle on a voltage I will get a contactor with that voltage.

Here is a link to my schematic diagram for the 36v contactor setup that disconnects between the controller and batteries - if you hit the switch all power shuts off:
http://www.endless-sphere.com/forums/viewtopic.php?f=28&t=10428&hilit=cortina&start=30

My questions revolve around how much current do the contactor and a dc/dc converter take and is it worth it? Having a fail safe shut off while riding is necessary but if the contactor method draws to much then it would be good to find another way.

A friend is building a electric motorcycle and he currently (early in process) uses the pull the Anderson connector apart with a rope method.

D, are you going for a dc/dc converter to run some kind of LED light system? If so, what do you think of this:
http://www.harrisonspecialties.com/mm5/merchant.mvc?Screen=PROD&Store_Code=HS&Product_Code=SmartFlash&Category_Code=MODULES
Any other comments about this as a "controller" for an LED lighting system? I think it needs 12v but with a dc/dc converter...piece of cake.
Maybe this should be another thread like "LED lighting for eBikes" or the like - not wanting to hijack this one...

Hope this helps.

Roy

 

[Anonymous]

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[deecanio]

D, are you going for a dc/dc converter to run some kind of LED light system?
Roy

Hi Roy,

Steve is taking care of my electrics (as ever) as i don't have enough knowledge to wire for myself yet but my understanding i need the dc/dc between the kill swicth and the relay to actually cut the pack supply?
i don't plan any lights although i know other use the dc/dc's exactly for this purpose, i think to give a 12v supply for the lights/instruments whilst using power from the pack itself?


cheers,

D