Hall Sensor preventing bike from working

[AnotherOne]

Hello, I'm a new member looking for some assistance. A while back my ebike stopped working after a fall and i've been trying to troubleshoot it ever since. It makes a rumbling or a high pitched sound when I try to drive the motor in any way, and it either tries to spin the back wheel but doesn't have enough torque to move on the ground, or doesnt spin at all. I think it depends on the starting position.

After some testing with my multimeter, I confirmed that the battery is working fine, the throttle is working fine, the brakes aren't interfering, and the controller seems to be operating as usual. I did the normal test for the Hall sensors, spinning the back wheel backwards manually, and tapping into where the sensors plug into the controller. While the yellow and green sensors alternate between about 0 and 5 volts as expected, the blue sensor is stuck at 5v.

Ok, so there's my problem, so I can just replace the sensor, right? Well the problem is that I did exactly that, and it's still not working. I gutted out the old sensor and put in a new one I bought from eBay. It still doesn't work, although it might be behaving a tiny bit differently now (in terms of when it chooses to apply torque), kinda hard to tell.

So I check the 5v and ground lines going into the blue sensor, and they're both operating as usual. It's just the output is a big fat 0, which is not a good sign considering the yellow and green sensors at least give off about .1v, even when set to low. This one just gives a ±.001 or something really small like that. When I move it to the magnet manually, it goes to like ±.006 or something marginally bigger like that.

So in conclusion, im stumped. Were the signs before I replaced the sensor indicative of a bad hall sensor? Or would something else be the prime suspect? How much does the specific model of hall sensor matter? It's kind of hard for me to tell the model because the sensors are stuck in these little wells, and I couldnt get the blue one out without breaking it to pieces. Were the symptoms after replacement normal for putting in the wrong model, or is it worse than that? I don't even know how I would look up this specific problem at this point. That's why I came here. Appreciate your help!

[Bikemad]

Hi andto the forum

I did the normal test for the Hall sensors, spinning the back wheel backwards manually, and tapping into where the sensors plug into the controller. While the yellow and green sensors alternate between about 0 and 5 volts as expected, the blue sensor is stuck at 5v.

So I check the 5v and ground lines going into the blue sensor, and they're both operating as usual. It's just the output is a big fat 0

As you have 5 volts at the controller end of the blue Hall wire and 0V at the Hall sensor end, there is obviously a break somewhere along the wire, which was presumably damaged during the fall.
The wire will either have been squashed/damaged by something externally, or the inner conductor may have simply been pulled apart by an excessive tensional force being applied to the wires during the fall.

As you don't mention which motor you have, I suspect the Phase and Hall wires might exit through the end of the hollow wheel spindle, in which case they can easily be damaged if the axle rubs/knocks against the ground.

If you cannot see any visual signs of physical damage, you will either need to carry out a continuity check along the blue wire using a multimeter and a sharp pin to locate exactly where the break is and repair it, or run another wire from the Hall sensor directly to the controller connector.

Were the signs before I replaced the sensor indicative of a bad hall sensor? Or would something else be the prime suspect? How much does the specific model of hall sensor matter? It's kind of hard for me to tell the model because the sensors are stuck in these little wells, and I couldnt get the blue one out without breaking it to pieces. Were the symptoms after replacement normal for putting in the wrong model, or is it worse than that? I don't even know how I would look up this specific problem at this point. That's why I came here. Appreciate your help!

As the Hall sensor was obviously working fine prior to the fall, the problem was obviously caused by the fall. Hall sensors are solid state devices which are unlikely to be physically damaged by a fall. 
A proper check of the Blue Hall sensor wiring might have saved you a lot of time and trouble, but I now suspect that you may have inadvertently replaced a good Hall sensor with a new one, which now appears to be faulty. 

If the Hall sensor has the correct supply voltage and is properly grounded, the output should still vary between high and low (either switched or proportionally depending upon the sensor type) when a magnet is introduced. If it is a latching relay (like the Honeywell SS41) it will remain switched (either high or low) until it is subjected to an opposite magnetic field.

Check out my poor quality video showing how a latching Hall sensor works.
Please note: the apparent varying intensity of the led visible in the first part of the video is a result of the automatic exposure function of the video camera, and has nothing to do with the proximity of the magnets to the Hall sensor. With the Honeywell SS41 latching Hall sensor the LED is either fully On (maximum brightness) or completely Off, and there is no voltage variation in between (unlike the A1302 linear Hall sensor shown in the second part).

I suggest that you test the Hall sensor again, and if turning the magnet around (using the North pole instead of South pole or vice versa) does not make it switch high, then I suspect that the Hall sensor that you have fitted is either unsuitable, or may have simply been damaged by excessive heat while attempting to solder the wires onto it. 

The replacement Hall sensors that are typically used are Honeywell SS41 or equivalent.

Alan
 

[AnotherOne]

Hello, thanks so much for your response!

I am still a bit skeptical that the sensor wasn't having issues, since I think I actually remember tapping into the output directly from the pins on the sensors, going through no wires, and the old blue sensor was still a big fat zero, while the sensors connected to yellow and green were outputting fine. I think I did that check after checking the motor connector, then proceeded to buy new sensors. Sorry for not mentioning that in the original post, a lot of this happened a while ago and I'm still jogging my memory. Hmm.

But if I did replace the Hall Sensor for no reason, the replacement model I bought is definitely incompatible based on what you told me and that video. And the new sensors I bought definitely didn't burn out because of soldering issues or anything like that, because after it didn't work I tried hooking up a fresh one with alligator clips and whatnot and I still got a big fat 0 (shouldve done that first  ), despite the input positive and ground lines working fine. It's ok though, I already bought some Honeywell SS41s online, and hopefully I should be able to get that aspect back to where it was when I get back home Sunday. A little time lost, but not the end of the world (trying to stay positive here)

Despite this, I definitely see what you're saying about Hall sensors being solid state and hence pretty unlikely to fail. I was really hoping it wasnt a wiring problem, because I had no clue how I would even go about testing that, so thanks for telling me to do a continuity check! I can't believe I didn't think of that myself, I'd seen others do such a thing online but it never crossed my mind. So I do a continuity test from the start of the output wire to where the wire plugs into the motor controller. I test yellow. Beeeeep. I test green. Beeeeep. I test blue....dead silence. I even tested from where the blue wire starts to ever so slightly along where the blue wire starts, just to make sure that end was connected properly. It was. There's just no signal making it out the other side.

EDIT: I had my finger on the send button, but I decided to take one more, thorough look at the wiring, and, just like you said, where the wires leave the spindle it got totally cut open! I couldnt see it because it was covered by a spring (presumably for strain relief), so I inspect further and the blue wire is completely and totally cut! LOL so call me crazy, but I think we found it. So when the honeywells come in I'll have to install it, solder it up, solder up the broken wire, and hopefully that should do it! Thanks sooo much, I'll let you know how it goes!