speed indicator hall sensor wire

[basement]

Hi Community,

I'm finalising my Vespa conversion. it's been a trial and error kinda build, but coming along nicely now.
If there is interest I could post some pics and info about how I went along.
2 things still bug me (at this stage)
I can't seem to get speed reading on my XP Motor universal LCD Display.
It's powered up all functions work and the 'hall' wire is connected to one of the hall sensor wires. (I tried at the motor and at the controller side) .
As soon as I let go of the throttle, the speed appears !?! and slowly counts down with the wheel returning to a full stop.
What did I do wrong?
it's a QS 205 50H V3 3Kw motor and a Kelly KLS7230N controller.
could this be a setup in the controller menu?

thank you for all your input and help.

While on subject, how do I isolate the 2 current circuits in my build?
I have a 60V motor and controller circuit and a 12V auxiliary circuit but my DCDC gets power from the main 60V battery.
And thus the circuits get mixed, although I want to keep them separated.
any idea's on that?

Thank you guys,
All the best,

 

[amberwolf]

i don't know about the display / speed indicator issue...it's very strange that it works whenever throttle is not engaged, but not when it is.

it almost sounds like there's a missing ground wire between the display and sensor.

you might try an external speed sensor, like one from a common bike computer. uses a magnet on the wheel spokes to measure speed. if you don't have an old bike computer you can get them cheap, or even just order the wheel sensor and magnet from http://ebikes.ca .


regarding the "mixup" of the other circuits, i don't understand what you mean. could you explain in complete detail exactly what you mean?

 

[basement]

HI Amberwolf,

Thank you for the reply.
as it clearly is a faulty wire connection / a missing wire or a setting I would like to proceed in finding the solution to this problem.
I'm trying to do slick/stealth conversion, adding a speed controller on a wire to the front wheel is not an option )

The common ground issue might not be an issue at all.

Somehow I feel like having 2 different isolated circuits is the better option, to avoid possible issues.
I read a lot about controller issues and weird motor behaviour, and most came down to an issue somewhere along the 12V circuit.
Thats why I would like to keep my 60V circuit (powering motor and controller) separated from the 12V circuit (powering lights/horn/indicators/...)
if I lose my 12V circuit, for some reason, I can still drive. And a short in the 12 V circuit will not influence the Power to the motor and controller.
Only problem in this setup is that I need to power my DCDC (60 to 12) of the 60V battery and thus create a direct connection between both circuits.
Hope this explains it better;

 

[amberwolf]

as it clearly is a faulty wire connection / a missing wire or a setting I would like to proceed in finding the solution to this problem.

if it's a bad connection, like bad ground, you can check that with continuity test mode on a multimeter; if it doesn't have a continuity (or diode) check you can use the lowest ohms setting instead. do the tests with battery disconnected from the system. red lead of meter goes on one end of the wire under test, at the display, black to the other end at the controller.

(throttle ground is probably ok, since the system isn't stuck at high or full throttle, which is a symptom of missing throttle ground).

settings i can't help with, as i don't know anything about your specific controller and display. if there is an online manual for your display, you could link to it and that might help us help you. or if you have a version you can upload and attach to your post.

I'm trying to do slick/stealth conversion, adding a speed controller on a wire to the front wheel is not an option )

you're not adding a speed controller, just a small sensor. they are common enough on regular bicycles, so isn't going to change the stealthiness of it. (might change the look you're after, but nothing really to do with hiding the ebike status vs a normal pedal-only bike).

doesn't have to be on the front wheel, can be on the back.

Somehow I feel like having 2 different isolated circuits is the better option, to avoid possible issues.
I read a lot about controller issues and weird motor behaviour, and most came down to an issue somewhere along the 12V circuit.
Thats why I would like to keep my 60V circuit (powering motor and controller) separated from the 12V circuit (powering lights/horn/indicators/...)
if I lose my 12V circuit, for some reason, I can still drive. And a short in the 12 V circuit will not influence the Power to the motor and controller.
Only problem in this setup is that I need to power my DCDC (60 to 12) of the 60V battery and thus create a direct connection between both circuits.

if you want the 12v completely separate, you must use a completely separate 12v battery, not a dc-dc. (or a completely separate battery to run the dc-dc, with neither connected to the traction battery that runs the motor)

i use a completley separate battery for my lights, vs my motor, simply so that even if i run out of motor power in it's battery, i still have lights to be seen on the road, as well as to see.


there isn't a way to power the dc-dc from the traction battery without connecting positive and ground of the traction battery to the positive and ground inputs of the dc-dc.


if you want to prevent a short from the output side of the dc-dc from affecting the motor system or traction battery, then you can use an isolated dc-dc (meaning there's no electrical connection isnide the dc-dc between input and output; some of htem have a common ground wire, and are not isolated).

you can add a fuse between the dc-dc input and the traction battery output, so in a short internal to the dc-dc itself it will blow the fuse and prevent problems with the motor/battery.

and you can add a switch between the dc-dc input and the traction battery output, so you can turn off the whole dc-dc system if necessary, without affecting the traction system.

 

[basement]

Hi AMberwolf,
Hi all,

If anybody would be interested I contacted both Kelly controllers and QS motors.
Got an answer from both
And connecting the hall sensor wire from the display to pin nr.8 on the controller connector
(8: Meter: Copy signal of hall sensors) solved my issue.

Hope this can help somebody else.
All the best, and thanks for your replies.