Deadman switch

[MidniteTweeker]

Somewhere on this forum I ran across mention of a deadman or e-stop switch. I'm working on my first project now, and It got me wondering if this is something I should include for safety reasons? Thinking about it, there are similar precautions taken on other vehicles. Motorcycles have handlebar mounted kill switches. Motorcycle throttles use pull-pull cables so a stuck throttle does not rely on spring return. Cars have ignition switches. But what does an electric bike do if the throttle malfunctions? Has this ever happened to anyone?

I don't have a controller in hand yet, but I'm wondering about using the brake lever motor cutoff circuit. Initially I did not plan to use this feature, but now am having second thoughts. Even then, as a safety circuit, how reliable is it? Better than nothing, I suppose. But if this were a piece of industrial automation an electronic safety circuit would never fly. Automation wants hard contacts to open, and there needs to be redundant contacts and circuits to guard against contact welding.

Without an e-stop, would could you do with a throttle stuck wide open? Grab the brakes, sure. And then hope you could maintain enough control to hop off and turn the keyswitch on the battery pack? Yikes, this ratchets up the old pucker factor!

Thanks,

MT

 

[broloch]

I figure some sort of high amp on/off switch.
As for a kill switch, kinda like on a treadmill. If you go on a treadmill there is a tag you can clip to your belt, that is attached to the treadmill, if you fall off the tag will pull a card out of the treadmill and will kill the engine.

Like if you fall off a jetski, the jetski will shut down, because you have an activating switch attached, wired from you to the craft. If you fall off, it will pull the key out.

 

[MidniteTweeker]

if you fall off the tag will pull a card out of the treadmill and will kill the engine.

Yeah, that was my thought too. Only problem is, I'll be motorizing a tadpole trike, so falling off isn't too likely, for better or worse. But something like that where maybe there's something---maybe a loop of cord or wire---on the handlebar that could be grabbed and pulled to activate a cutoff switch. I'm normally not too paranoid, but I'll admit that imagining the possible consequences if the motor suddenly couldn't be shut off has me thinking.

Do commercially built electric bikes or scooters use anything?

MT

 

[docnjoj]

I got a "poor mans deadman switch" on my Tadpole! Its a standard 20 amp light switch mounted right below my seat! This turns the bike on, and, recently, helped save it from running away when my brushed controller failed open, leaving me to chase the trike around the yard until it hit the stairs! It just kept spinning the rear wheel, but I think that caused the demise of my geared hub motor. It could have been worse if I had been in traffic!
otherDoc

 

[Drunkskunk]

pretty easy to make, if you want one. a brushless motor won't have the stuck open throttle problem, but controllers like the C-lytes usualy have a brake over ride, that kills the motor if the brake lever is pulled.

But a main power cut off is a good idea. since you're seated, and I assume the battery is behind you, you could run an extra leingth of the positive wire to the bar infront of the seat and back. then add a power pole conection to it, and put it facing you. then add a thick wire jumper to it in the shape of a handle, like an ejector seat. pull it and disconect the battery.