Can't decide how to wire the on/off switch

[Bigbikebob]

My Lyen controller has an ignition wire that is connected to 48V of the positive battery lead and to a key-switch which, when turned will cut on/off the ignition.

I want to add a on/off switch on my handle bar so I can turn off the bike if I need to without using the key-switch.
For example, a few days ago I was on the bike with ignition on and talking to a friend and he put his hand on the throttle and could have done a lot of damage.

As I see it I can do this in 2 ways
I can take the ignition wire that is already connected to a key-switch and add to it another on/switch on the handlebar. The the downside is the 48V on the handlebar.

I can connect the on/off witch to the controller ebrake wires and every time I flip the switch the controller will get the 5V brake signal and cut off the motor/ throttle.

In both of this cases the controller is still connected to the battery. so it is not a switch that disconnects the battery from the controller.

So what is the safest option. does the ignition controller signal has the same priority as the ebrake? what I mean is in case of controller malfunction what would have more effect 5V from the ebrake or the 48V cutoff from the ignition.

 

[dogman dan]

For a short period kill switch, closing the circuit on the ebrake wires will do er nicely.

But it won't shut off the controller using it's 3-5 watts, so overnight, use the key switch.

If you need emergency shut down, then only the 48v circuit will cut power to the controller, stopping it.

FWIW, once I had a brushed controller fail the way they do. Stuck in WOT. Guess what, ebrakes did not stop it!!!!

Ebrakes are stupid IMO, but they do help if you make the mistake of rolling a throttle when pushing a bike around the garage. They will stop it, if you have a stuck or shorted throttle circuit.

 

[Bigbikebob]

they do help if you make the mistake of rolling a throttle when pushing a bike around the garage. They will stop it, if you have a stuck or shorted throttle circuit.

Been there, done that

If you need emergency shut down, then only the 48v circuit will cut power to the controller, stopping it.

The question is does the controller uses the ignition wire as a signal that translates into "0"/"1" , and logic tells me that 48V is too high voltage for a signal which is usually 5V or does the ignition wire intended not as a signal but as a power source for the controller (like you wrote If left it on for the night it will draw some W) and in case you cut it off you literally "pulling the plug".

*My older setup was based on a full kit I ordered from chonismotors and had a very generic controller with no ignition wire. the battery pack had a key that just killed the whole system.
Not a very safe option if you have a controller malfunction that causes WOT while you are riding.

 

[teklektik]

My Lyen controller has an ignition wire that is connected to 48V of the positive battery lead and to a key-switch which, when turned will cut on/off the ignition.
...
I want to add a on/off switch on my handle bar so I can turn off the bike if I need to without using the key-switch.
...
I can take the ignition wire that is already connected to a key-switch and add to it another on/switch on the handlebar.
...
In both of this cases the controller is still connected to the battery. so it is not a switch that disconnects the battery from the controller.

Well, yes and no.
The controller has two parts: (1) the FETs that drive the motor phase power and (2) the rest of the electronics (processor, etc). The FETs are essentially an open circuit without the rest of the stuff to turn them on. The ignition wire supplies power to the electronics, so the keyswitch actually does disconnect the critical part of the controller from the battery. When this is turned off the controller as a whole draws negligible power and is essentially brain-dead - even though the FETs are still hooked up.

On the other hand, the ebrake inputs are sampled and acted upon entirely by the processor (software). Everything stays powered up and for the ebrakes to work relies on the processor et al operating as designed.

So - what you really want on your bike is a 'kill switch' reachable from the throttle by thumb that breaks the ignition (keyswitch) circuit and forcibly shuts down the controller. This will kill the bike regardless of how the controller fails or goes berserk. The older controller that had a keyswitch and no ignition wire - actually did. It was identical, but just packaged internally. You could have opened the case and spliced a kill switch into the keyswitch wire exactly as with an external ignition wire.

Don't worry about the Vbatt on the handlebars - just use good wiring practice. You can use an off-the-shelf light switch or fab something yourself. The current is very small so arcing is not an issue - common low-voltage (automotive) switches, etc are fine.

There is a large faction that believes that all ebikes should have a kill switch for safety reasons (think about how simply breaking the throttle ground wire will typically cause a controller to wig out and take off at WOT - while you are holding on for dear life, a flick of the thumb can save your butt )...

 

[Voltron]

I became a believer in bar mount cutoff switch after that exact thing....bad throttle wire making the bike jump to full power...in traffic! I reached down and grabbed wires and yanked! Lol. And controllers with ignition wires are great too...no sparking hooking up the batteries.

 

[dogman dan]

Ignition circuits I've seen were all pack voltage, in this case 48v. Current carried is low, so 48v is not so scary. But as always, you do have to have some decent protection on the wiring if it's going all the way to the bars.

If your bike is going to be very powerful, you might even consider the deadman switch tied to your wrist thing, like a jet ski.

I've never had a throttle go WOT on me, so I stopped worrying about that one much. But I don't run 5000w or more either.

 

[Voltron]

Mine picked a terrible time to do it, right in heavy traffic. When I got to a better spot, I kept poking around with my finger at low speed, and found the spot on the throttle wire that when poked....the bike jumped! lol ..No visible exterior damage either.

 

[Drunkskunk]

With the ignition wire off, the controller Is still drawing power. While the amount is small and varies between different controllers, it can easily destroy a battery if left plugged in but "off" in a mater of days.

A cut-off of some kind is nice when moving the bike around. A simple kill switch could be put on the bars in place of the brake cut off. However, for my bike I took advantage of position 1 of the 3 speed switch. I set the programming to 0% throttle, so the first position is "Off". The other positions I set to "I swear she's legal, officer" and "Hold my beer and watch this."

As for a total kill switch to protect against a run away motor, Sure. Makes sense. But probably unnecessary. Your brakes should be able to lock up the wheel with the throttle pegged. I know my BB7s can lock up my monster motor pumping out >12,000 watts with a just a 203mm disk. That causes the motor to stall, and the controller to cut it off.

 

[Bigbikebob]

The ignition wire supplies power to the electronics, so the keyswitch actually does disconnect the critical part of the controller from the battery. When this is turned off the controller as a whole draws negligible power and is essentially brain-dead - even though the FETs are still hooked up.

On the other hand, the ebrake inputs are sampled and acted upon entirely by the processor (software). Everything stays powered up and for the ebrakes to work relies on the processor et al operating as designed.

Thanks, exactly what I wanted to be sure about.

The older controller that had a keyswitch and no ignition wire - actually did. It was identical, but just packaged internally. You could have opened the case and spliced a kill switch into the keyswitch wire exactly as with an external ignition wire

Make sense.Problem is, during my first e-bike build I had no idea how to use a multimeter

There is a large faction that believes that all ebikes should have a kill switch

I totally agree.

I became a believer in bar mount cutoff switch after that exact thing....bad throttle wire making the bike jump to full power...in traffic! I reached down and grabbed wires and yanked! Lol

Sounds like an "excellent" way to learn a lesson

I've never had a throttle go WOT on me, so I stopped worrying about that one much. But I don't run 5000w or more either.

I prefer to be safe then sorry. There is a saying in the military "Safety instructions are written with blood" I prefer keep mine to myself.

for my bike I took advantage of position 1 of the 3 speed switch. I set the programming to 0% throttle, so the first position is "Off". The other positions I set to "I swear she's legal, officer" and "Hold my beer and watch this."

interesting solution

Your brakes should be able to lock up the wheel with the throttle pegged.

That is a brute force solution that can damage the brakes and motor. let me rephrase that, if you are holding a hammer that doesn't mean every problem is a nail.

Wired the cutoff switch and here is the result.

 

[d8veh]

With the ignition wire off, the controller Is still drawing power. While the amount is small and varies between different controllers, it can easily destroy a battery if left plugged in but "off" in a mater of days.

A cut-off of some kind is nice when moving the bike around. A simple kill switch could be put on the bars in place of the brake cut off. However, for my bike I took advantage of position 1 of the 3 speed switch. I set the programming to 0% throttle, so the first position is "Off". The other positions I set to "I swear she's legal, officer" and "Hold my beer and watch this."

As for a total kill switch to protect against a run away motor, Sure. Makes sense. But probably unnecessary. Your brakes should be able to lock up the wheel with the throttle pegged. I know my BB7s can lock up my monster motor pumping out >12,000 watts with a just a 203mm disk. That causes the motor to stall, and the controller to cut it off.

The drain from modern controllers with the ignition off is supposed to be in the range of microamps. At 10 microamps it would take 114 years to drain a 10Ah battery. There must be more drain than that because you often get that snap from the capacitors when you connect after some time disconnected, which implies that the capacitors or something else is leaking; however, I often leave mine for months at a time with the ignition off and the battery still connected. When I eventually switch on, the meter always shows the battery to be fully charged.

 

[dogman dan]

The important part of that phrase, "should be".

But yeah, parked overnight or for a few days ignition off battery full should be fine. Should be fine battery half empty. I don't recommend it for parked battery really empty.

So much depends on how long you park it, and the state of charge when parked. For more than a week, unplug I say. That advice is written in the blood of my first pingbattery. Riding home with west nile virus and a fever, I parked the drained bike for two weeks with the controller completely on, drawing 3watts. You'd think the bms would have stopped it, but the bms still allowed the pack to drain till it puffed all to hell. I suppose the cut off fet was blown and I did not know it.

 

[Drunkskunk]

Yeah, it's the "should be" that's the killer. In theory, capacitors block DC. In reality, they leak small amounts of DC current. Those are going to be the worst offender in most controllers. Diode junctions in transistors and the FETs also leak small amounts of current. Ideally that should be micro amps, but in reality it can be mili amps, and when all the diode connections are leaking, that can start to add up watts per day.

And to make things more confusing, there where a few controllers that had drain down resistors for the main capacitors, probably as a safety feature. While I haven't seen one in a while, I wouldn't count on a cheap ebay kit not having one.

A 36v 10AH battery drained to 80% after a ride still has 72 watt hours left in it. If your controller draws 0.02 amps when off (0.72 watts) that will drain the battery to 0 capacity in 100 hours. So in 4 days your battery is fully drained. In 5 days it's trashed.

So Lets say you park your bike and just turn it off, fully intending to come back and charge it the next day. Then life happens. It rains for a week. Your kids all get colds. Your girlfriend gets in the mood for 5 days straight. Your wife finds out. Something. So it takes a week to get back to the bike, and now you could come back to a ruined battery.

I've had more than a few controllers since I got started. In that time, I've only had one that only leaked only in the mili watt range. Every other one I've ever had access to leaked 5 to 30 watt hours a day.

 

[Micmartin12]

I have a voilamart stealth bomber and it has a keyed ignition with a red wire and a white wire. I don't have a controller connected so how would i connect the ignition.

Sent from my SM-N981U using Tapatalk