What is a good way to add a kill switch

[chrashing]

I was looking at toggle switches to put on the lead of the 48V battery to the 30amp controller. Found a 30amp switch, but then noticed it was for 12 volts, and see that the current capacity is reduced as the voltage increases. Beginning to look like I need a very hefty switch to handle all this current. So now I'm thinking that I should ask for info on how this is normally done....

Is the kill switch usually on the battery power line (high current)? Or is the kill switch put on one of the controller circuits, like to disconnect the throttle, so a low current switch can be used to stop the the motor? What is a good way to do this?

 

[e-beach]

I was looking at toggle switches to put on the lead of the 48V battery to the 30amp controller. Found a 30amp switch, but then noticed it was for 12 volts, and see that the current capacity is reduced as the voltage increases. Beginning to look like I need a very hefty switch to handle all this current. So now I'm thinking that I should ask for info on how this is normally done....Is the kill switch usually on the battery power line (high current)? Or is the kill switch put on one of the controller circuits, like to disconnect the throttle, so a low current switch can be used to stop the the motor? What is a good way to do this?

If your controller does not have built in "anti-theft" settings, there is probably thousands of ways to stop a thief or a joy riding friend from riding your e-bike. If you want to go with a kill switch, hiding a switch somewhere on your bike could work.

I run a rocker switch with my 30 amp controller. I run it inline with my battery to controller wiring on the positive wire.

The switch I use rates like this: S.P.D.T., center-off rocker switch. Black bezel and rocker. Marked 1-OFF-2 in white letters. Rated 16A/ 125Vac, 3/4HP / 125/250Vac. and it is from http://www.allelectronics.com/make-a-store/item/RS-179/ON-OFF-ON-ROCKER-SWITCH/1.html

It might be under rated for the job, but it works. If you feel the need for a more robust switch here is one from amazon: http://www.amazon.com/Rocker-Switch-Polarity-Reverse-Control/dp/B001PNIJM2

Putting a kill-switch in line with the throttle is a fun idea. I hadn't thought of that! :lol: Just make sure it has a low enough resistance so it doesn't affect your performance.

 

[amberwolf]

Lots of threads on this with more info.

Brushless? Many controllers have a "keyswitch" wire that must be connected to battery positive to work.

Or use the ebrake line if you don't use regen.

There's almost no condition that would keep the motor running with a hardware failure while battery is still connected, with one or more of those things.


Brushed? Some controllers stop when trhottle is disconnnected. Some have ebrakes. Some may also have keyswitch wire. But unlike brushless, if the MOSFETs fail they usually fail shorted, leaving motor at full power, so brushed requires a killswitch that can handle full-voltage and full-current at the same time and still disconnect without arcing. They are large by their nature. A small switch that engages a contactor (relay) is usually better. Either system can be expensive.

 

[tony67]

I have my kill switch wired into the signal wire of my throttle. It works a treat and only requires a simple 12v handlebar switch. I toyed with the idea of wiring one inline with the battery but the power running through it required far too big a switch and I could not find a suitable item.
Since the signal wire carries only 5v any handlebar switch will work just keep your cable run short. I have noticed no ill effects since the install and have been running it for nearly a year now.
Hope this helps
Tony

 

[alex12342011]

Couldn't you also add two switches in parallel with each other?

EDIT: Tony's idea may be more practical.

 

[dnmun]

and you can put a switch in the circuit current for the BMS unless you have lipo. that would turn off the battery so even in a wreck you could stop it shorting out. saves the problem of creating the antispark circuit too.

 

[miro13car]

by "kill switch"
you need it for safety as a rapid cut off switch or rather as anitheft???
If for safety:
- there is no better way than break levers trust me, because you must be fast
Both of my ebikes use break levers as safety cut off, there is no better way , lot's of ebikes use it, why try to "discover America".
Rocker switch or toggle or whatever switch will not work TOGETHER with breaks like break levers.

 

[chrashing]

Thanks for all the great advice, has really helped me get my plans together. Hopefully I'm getting onto the right track. I'm just getting the parts for my brushless motor trike together, and this is what I'm planning:

Not going to put a switch off the battery, just disconnect the connector or pull the fuse. Turns out the thumb throttle I received has a push button on/off switch, so that will work as the main mother on/off switch.

micro13car, I'm going to wait on buying a brake with motor cutoff switch, will see if I tend to ride the brakes with the motor powering. Also if I add a hidden cut off, was now thinking to put a (small, low power rated) toggle switch in parallel with the two brake switch signals, Expect they are shorted together to stop the motor. Are you saying this will not work?

Dnmun, Your suggestions sound interesting, but I don't know the BMS circuits well enough to consider this for the LiFePO4 battery I ordered.

 

[dnmun]

post up a picture of your BMS when you get it. i just ordered a buncha one position dip switches to go onto the signalab BMS. so anyone with the ping signalab BMS can usue it for switching the circuit current on and off on the signalab. can adapt them to the other BMSs too. 14 cents each.