Half Twist throttle how do I adjust the off band?

[DAND214]

This is the second throtte that has changed the dead band. In order to stop I need to open the throttle about a 1/4".

First one I thought was the heat that caused the HALL sensor to change. First time I thought it was the controller but during testing it turned out to be the throttle.

I have checked the magnet location and also the HALL, Both are in the proper position.

If I turn the throttle just a little it stops the motor, let go and it runsabout 7 mph. Top speed seems to be normal.
Both throttles are from Cell-man, half twist with 3 speed and cruise button. Both worked for about two months with no problems.

I road the bike yesterday only 5 miles and seemed normal. this morning I went to ride and after the first power on run it wouldn't stop totally.

I opened the throttle to check the positions of the magnet and the HALL. The magnet is about a 1/4 past the HALL. Turn the throttle so the magnet is in front of the HALL and it stops.

Any ideas? I don't see any plastic chipped or broked and the mag is captive. Do the mags loose strenth an thn cause this runaway?

I think I can reposition the magnet by stopping the twist throttle a little back. Think that will work? I have other halftwists for years but never had this happen.
help!?

Dan

 

[d8veh]

I've never experienced that problem, but I've done a couple of experiments on throttles. I can't say all throttles are the same, but there's a high chance yours is the same. Maybe this info can help you understand what's going on.

The hall sensor gives out a middle signal when there's no magnets present, so you get half throttle. When you bring a south facing magnet to the hall, it pulls the voltage down to about 1.3v. The magnet has to be right up against the hall to get the signal low enough for zero throttle. When you bring a north facing magnet to the hall, it increases the signal voltage to about 3.7v. It also has to be right up against the hall to get full throttle.

The throttle spring pulls the south facing magnet to the hall, so if anything was worn, it could go too far, which would have the same effect as opening the throttle, but I think you would see some damage. I could understand the full throttle stop being damaged, but not the low one.

 

[Thud]

You just need another throttle that works right.....or tune the one you have with resitors.
Denisisiwa shows the method here:
http://endless-sphere.com/forums/viewtopic.php?f=28&t=46891#p686535

Works the same on a hall throttle as the magura.

 

[skeetab5780]

I've had a few half-twist throttles do this to me, I took a used throttle out of a brushless pedal assist bike I had kicking around thinking it would be the same thing. After I installed it on a normal brushless controller the wheel would spin at like 5mph when I hook my batteries up. Long story short.. you take a little cover off the half-twist throttle and there was a way to adjust the magnet so that the wheel didn't spin (move magnet up or down) to a different spot in the plastic molding.

I'm pretty sure I still have the throttle somewhere, maybe I can find it.

 

[DAND214]

I've never experienced that problem, but I've done a couple of experiments on throttles. I can't say all throttles are the same, but there's a high chance yours is the same. Maybe this info can help you understand what's going on.

The hall sensor gives out a middle signal when there's no magnets present, so you get half throttle. When you bring a south facing magnet to the hall, it pulls the voltage down to about 1.3v. The magnet has to be right up against the hall to get the signal low enough for zero throttle. When you bring a north facing magnet to the hall, it increases the signal voltage to about 3.7v. It also has to be right up against the hall to get full throttle.

The throttle spring pulls the south facing magnet to the hall, so if anything was worn, it could go too far, which would have the same effect as opening the throttle, but I think you would see some damage. I could understand the full throttle stop being damaged, but not the low one.

Thanks d8veh for the tech lesson, wasn't sure exactly how it worked other than the mechanics of it.

I have had throttles that were cutting out in full throttle due to higher voltage than needed but not this problem

I thought that by letting go of the throttle and the snap back had caused a broken stop but still not sure.
Will open up a new one to be sure and post results later..

There is no adjument of the magnet without hacking the holder. It snaps into a fixed opening.

Thanks again guys.

Dan

 

[DAND214]

I found it!

Small broken piece of plastic that stops and ppositions the throttle.
Black on black is really hard for me to see. Bad design, since it's only a small 3/8"w x 1/32" piece that has no support but the rocker that is by it. No angle pieces to reinforce it.

The reason I didn't find it sooner was the other did the same thing, so looking at a new one showed the missing stop.

I always by an extra when ordering from anywhere. Shipping is more that the part.

Dan