Where to connect the single wire speedometer wire?

[ebike11]

Hi guys
Im helping a friend with his ebike. He has no lcd display. Just an on and off switch connected to his controller. He has of course his battery pack and motor connected to the controller as well.
We noticed there is a single wire from the controller for speed. This is not the 3speed wire switch.
What would he need to make use of this wire? Is there a cheap speedometer gauge to connect to this wire?
Thanks

 

[dogman dan]

That would connect to something, either a magnet on the wheel, or to the motor itself in some cases. then use a display, that you don't have. Just add a regular bike speedo to the bike.

 

[ebike11]

Ok.
But if i added a regualr speedo then there would be no point in using this wire correct?

 

[dogman dan]

Yes,, you won't be using that wire. If anything, you'd need the display you don't have. Nothing wrong with just using a cheap wired, regular bike speedo. I found the wireless bike speedos don't work near a motor.

 

[Ianhill]

My sunwin controller has this green single wire for speedometer, Its connected to the halls in the motor pulses with them so if I took a MTB speedo and did not plug the magnet in but plugged this wire I then would be getting my speed signal direct from the motor rather than magnets on the wheels etc. The speedo needs to be adjustable to get the wheel rpms correct with the pulses coming from the motor but its all feasible with a £5 cheap speedo on eBay.

 

[dogman dan]

That makes sense. You'd need to set the speedo for what,, the equivalent of three magnets on a wheel instead of one?

Once you have the regular speedo though,, seems fairly easy to me to just put its sensor on the front fork.

If it's a geared motor, you won't get speed input from the motor while coasting,, so that's one reason to just go regular speedo.

 

[Ianhill]

The only time it would make sence to take rpm from the motor is if there's a clutch that engages so the wheels stops and the engine is still at a certain rpm but I don't see the need for it with electric unless I'm missing something.