Hall throttle signal issues

[veloman]

With gnd and 5v+ hook up to my throttle, I get these readings:
5v = 5.03v that's good
signal line with closed throttle 0.9v, up to 4.3v WOT. so far so good.

Now, when I connect the signal line to the controller, it is 1.9v. Because of this, I get a fault (and if I didn't the bike would move with no throttle movement).

What's the easiest way to fix this? A diode on the signal line?

 

[teklektik]

Makes no sense - there should be a pull-down resistor on the throttle input - not a pull-up.

What's the voltage on the controller throttle input lead w/o the throttle attached?

Do you have a CA V3 plugged in as well?

 

[veloman]

What's the voltage on the controller throttle input lead w/o the throttle attached?

4.79v on the input lead without the throttle connected.

No CA. The controller is from a Rmartin EVD scooter - 6 phase bldc. I am told by the shop I got the motor and controller from that it uses a hall throttle.

 

[dnmun]

use a 3V battery and apply the 3V between the throttle sensor input to the controller and ground and see if the motor will spin.

 

[teklektik]

4.79v on the input lead without the throttle connected.

I am told by the shop I got the motor and controller from that it uses a hall throttle.

Strange.
I've got to bow out of this one - no experience with a controller like that....

If it was mine I would hook up a 1K or 5K pot or a variable power supply and

• dial it up until the wheel started turning,
• dial it up more until the speed stopped increasing, and
• dial it up more until it faulted.

With those 3 voltages at least you would have a notion of what might provide a satisfactory replacement....

 

[veloman]

When I had the throttle connected and applied my multimeter leads to the gnd and throttle input lead, that actually got the motor to turn at about 15% speed. It seems the very low current in the tester was enough to drop the input voltage to the acceptable zone. But the motor would continue at that same speed with the throttle closed.

 

[teklektik]

Hmmm... Sounds like the controller internal pullup is very weak. Probably just enough to make the throttle fault if the controller is powered up with a broken throttle connection.

As I recollect, the halls they use in throttles appear as a voltage source with a diode facing the output so if you tie a couple together the highest one wins - apparently because the lower one is back-biased. So - right now the pullup is 'winning' over the throttle and you are getting the fault.

So - if you have some resistors around you might try tying the throttle input line to Gnd with something like 10K - 47K to pull it down to zero. The throttle should then be able to source current into it pull the line up normally. I think...

If you don't have resistors handy, you can get a pack at Radio shack for a couple of bucks.

I'm just winging it here....

 

[dnmun]

what speed did the motor turn when you applied the 3V?

 

[veloman]

I just put my precharge resistor between the gnd and throttle input and it works well now aside from the normal dead spots at the beginning and end.
I think it's a 1k 1/2watt resistor. With it connected, the throttle input is resting at .79v

Thanks for the help, I'm really happy to get this working.

 

[teklektik]

Excellent news.

Your 1K resistor is going to require the throttle source about 4ma at 4V which is a little higher than I might otherwise choose but you can't argue with: "works!". If you check you WOT voltage and it seems a little low, it's likely the lowish resistor value, but if no issue - go with it. You might try something like 5K for a permanent installation (I went with even bigger values above, but you get the idea). Any tiny wattage is more than adequate (1/8W, etc).

Glad it worked out.

 

[dnmun]

if you ground the throttle input with a resistor it should cut off the controller so the motor should not turn.