Elegant solution for 72v main power switch

I used one of these, but I wouldn't call it elegant. It will appear more elegant when I fabricate an aluminum channel frame around the bike's triangle, that I'll cutout to fit the breaker, but for now it's better than unplugging the battery when not in use:

https://www.amazon.com/gp/product/B000WUNRQ2/ref=oh_aui_detailpage_o09_s00?ie=UTF8&psc=1
 
If your motor is a 3 phase brushless, then there should be no need for a main power switch. Instead put a simple, cheap, reliable key switch on the low power input to the controller's logic section of the controller. Even my 20-30kw builds don't have or need main power switches. Safety features include an appropriate fuse at the battery, a key switch to cut power if all else fails, and ebrake switches to easily and intuitively cut off a runaway condition without letting go of the handlebar with one hand.

Elimination of unnecessary components is always the most elegant solution to me.
 
John in CR said:
Elimination of unnecessary components is always the most elegant solution to me.

I definitely see the appeal of this approach.

John in CR said:
Even my 20-30kw builds don't have or need main power switches

20-30kw? Wow, that's serious power! What voltages are these builds operating at? I'm using a Phaserunner on my 72v build and the remote on/off for that controller is at battery voltage (but with very low amperage), so one of my challenges is finding a switch to use here that will not be subject to arcing. Would you mind elaborating on what you use to switch your controller either here or in this thread: Remote On/Off Switch for Phaserunner V2
 
John in CR said:
If your motor is a 3 phase brushless, then there should be no need for a main power switch. Instead put a simple, cheap, reliable key switch on the low power input to the controller's logic section of the controller.

Are there no possible fail-on modes for brushless controllers?
 
Throttle failure (mech or elec)resulting in WOT springs to mind. Don't know of any others in brushless. Had a few hair raising brushed controller failures on my mtn board. Crazyscarry!
 
I'm using one of these with my phaseruner at 72v and it had been working fine for about 6 months. I'm a bike courier that had to turn my bike on and off about 30 times a day and haven't noticed any arcing.

Onever Universal Motorcycle Handlebar Flameout Switch ON OFF Button For Moto Motor ATV Bike
https://s.click.aliexpress.com/e/bPMPKHL2
 
Dumsterdave said:
I'm using one of these with my phaseruner at 72v and it had been working fine for about 6 months. I'm a bike courier that had to turn my bike on and off about 30 times a day and haven't noticed any arcing.

Please clarify, is this on the battery supply line? :shock: Or just in the controller ignition circuit?
 
No switch needed. Just plug and unplug the battery. Works well with Anderson SB50, easy to clean the contacts too.
 
TommyCat said:
Dumsterdave said:
I'm using one of these with my phaseruner at 72v and it had been working fine for about 6 months. I'm a bike courier that had to turn my bike on and off about 30 times a day and haven't noticed any arcing.

Please clarify, is this on the battery supply line? :shock: Or just in the controller ignition circuit?

It's connected to the 2 pin jst connector coming out of the controller
 
Chalo said:
John in CR said:
If your motor is a 3 phase brushless, then there should be no need for a main power switch. Instead put a simple, cheap, reliable key switch on the low power input to the controller's logic section of the controller.

Are there no possible fail-on modes for brushless controllers?

Without power to the logic chip there's no way for the brushless motor to make positive torque. If properly wired a brushless setup would require multiple simultaneous failures to create a runaway condition. eg A short of the throttle wire combined with failure of both ebrake cutoffs, but turning off the 0.1A or so power wire supplying controller's brain stops that in short order.

A bit of plug braking due to shorted failed power mosfets has been my typical failure result, which makes a DD hubbie controller failure a pain to pedal home. Anything from water to a dropped bike or loose wire can cause a throttle failure, so they are common, therefore, ebrake cutoffs are a mandatory safety feature intuitive to use. Reaching for a key or plug to cut power to the controller brain should be just a final line of defense to kill a runaway, and really shouldn't ever come into play anyway. I like key switches as a safety to prevent curious hands from making an idle bike hurt someone which adds a bit of theft deterrence. I find switching a key off to disable an otherwise silently ready to launch vehicle quickly becomes intuitive during dismount.
 
81style said:
John in CR said:
Elimination of unnecessary components is always the most elegant solution to me.

I definitely see the appeal of this approach.

John in CR said:
Even my 20-30kw builds don't have or need main power switches

20-30kw? Wow, that's serious power! What voltages are these builds operating at? I'm using a Phaserunner on my 72v build and the remote on/off for that controller is at battery voltage (but with very low amperage), so one of my challenges is finding a switch to use here that will not be subject to arcing. Would you mind elaborating on what you use to switch your controller either here or in this thread: Remote On/Off Switch for Phaserunner V2

74V to 115V nominal. I've used motorcycle key-switches readily available for under $10 on the same type of low current switch line you're talking about for over 10 years on a variety of ebikes for myself and others without a single failure. Many of those builds include the supply for the DC/DC converter for lights on the same key-switch, so I've been a bit surprised that contacts built for 12V use have held up so well at my pack voltages. There must be something in the standard design that prevent arcing, because I've replaced numerous charge connectors over the same time frame with a small fraction of the connect/disconnect cycles.
 
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