Electric Bike Hub Motor - How to Replace a Hall-effect Sensor

Brushless motors use electronic controllers instead of brush systems to control the timing and distribution of power to the motor. To do this, some controller systems use hall-effect sensors inside the hub, which track the motor's position. This information permits the controller to alternate power with the right timing and in the right sequence and, voila, it spins.

That's obviously the short version and it is a complex compared to standard DC motors, but brushless motors are more efficient and that's the benefit. Better efficiency means you get more mechanical energy per unit of power, which is a good thing! The bad thing is, hall-effect sensors are relatively unreliable in the hot, high voltage, rock-and-roll insides of electric bike hub motors.

In my case, the villain was voltage. Although, I certainly didn't help the situation when I crashed the stupid thing.

When the bike fell, the sensor and power leads--8 wires altogether--were crushed and severed as the axle ground against the concrete. As a result, the current intended for the motor found its way to one of the sensors and killed it as the heat changed the internal composition from silcon to silcon dioxide. The controller, as I said before, depends on these sensors to distribute power, so the whole system fails with the loss of even one of them.

Efficient, yes. Robust, no.

Sure enough, after repairing the wiring, I found that the motor didn't turn smoothly anymore. Rotation was jerky and it didn't produce much torque. This is known as "sputtering." There were also dead spots, where, if at rest, the wheel could not begin to spin. Major major problems. After a little research and hanging around the Golden Motor owner's forum, I learned that my problem was a failed sensor and it needed to be replaced.

This Instructable documents the process I followed to replace this sensor and bring my bike back to life.

First, a thousand thank-you's go out to myelectricbike, who walked me through this step-by-step, provided much of the information you'll read here, and is singlehandedly forging a first-rate forum for Golden Motor product owners.

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johnpeeter9 months ago
When the sensor is defective it may be difficult finding an alternative to this approach is to replace them all. In the end, it often goes to 1 when the sensor is bad, the motor can be very reliable,
ghans_0011 months ago
thanks for the info's! Bless you Sir!
Mike Rolite2 years ago
I have just found your article and it has solved a problem I have with my Chinese "Star & Moon" Electric bike. One of the three TO92 Hall effect sensors had failed but I could not find the Part No (S41351) anywhere on the internet, to know whether they were Bipolar, unipolar, latching or non latching types. I have even sent an email to the company in China without success asking them to identify the components.
The middle one was also fitted in upside down and I am not sure whether this was to make the little circuit board easier to manufacture or whether there was an electronic reason for this, as the magnets in the wheel are arranged "N" & "S" alternately.
I see that your TO92's are bipolar latching types and are all facing the same way but apart from that it seems to be almost identical to mine.
I look forward to getting my bike back on the road after about three months out of action
Thanks for sharing your story; I have learned a lot. God bless you bro
jjam13 years ago
We are replacing a hal sensor in a Daymak Gatto. Can someone tell me where this is
chinaeu3 years ago
very nice job.
could it be better if just buy one electric bike from the market.
here is our link:
If you use a sensor-less controller you can save yourself a lot of trouble!  Or use an HV (50V) radio control ESC.  You need a Hall-throttle to pulse width converter (a PIC works fine), but these controllers are TINY! 
177che4 years ago
This bike is true, I support what.
Take a look at how my folding bicycle
kfirco6 years ago
HI I purchase from china a brushless hub motor. Its 36v 350w. I am not sure if the controller is original for the motor but thats what they sent me. I connected all the wire from the controller to motor and Now I have left just the power from battery. The connector on the controller has 3 wires... red, black and orange. Can someone tell why is the orange for? I connect the + - from the battery and left the orange aside but it didnt run. Any suggestions?
if your controller 36V350W then it is the right one for the motor.
-the orange wire is for controling input(+36V) for the controller.
-you have to connect + from the battery to orange through a 20A fuse. then it will run. 
an alternate approach for when it is difficult to figuring out which sensor is defective is to replace them all. This can in the end make the motor more reliable because often when 1 sensor goes bad, another, or the rest of them have been weakened.
zjharva6 years ago
Is this a good kit? do you like it?
please can you tell me the adress where can i order the kit ,thanks
Jeremy.Nash (author)  zjharva6 years ago
The quality is great, relative to the price. And I do like it.
hy paws, im new in ,please can you tell me haw can i order a kit
Amberwolf6 years ago
If anyone is doing a repair like this and either doesn't have quick enough source of parts (for instance, needing the bike to get to work the next day :-) ) or prefers to do recycling of parts to fix things, many PC case and power supply cooling fans use a standard 3-pin Hall sensor that will replace those in BLDC motors (since those fans *are* BLDC motors, though very simple ones).

Some of the fans use an integrated Hall sensor and motor driver chip, which isn't typically adaptable as just a sensor, and they usually have 4 or more pins, instead of the typical 3 (as in this instructable's photos). If that's the only fans you have laying around, you'll have to order your sensors anyway. :-)

I know many people that either themselves have or know PC-repair friends that have old worn-out cooling fans laying around, so they are a reasonably practical alternative for these sensors. I'm using some myself in a motor I'm converting from an old cieling fan into an e-bike motor for various testing purposes (see for the info I've posted about the e-bike project).
nzlee346 years ago
if you add a bit more control circuitry it is possible to eliminate the hall-effect sensors completely.
Like the controller from a treadmill... That's what I use. It is about 2kW with a 2HP motor, and I could get up to 90 on it... My wheels melted the last time I tried though, plus the bearings were shot. Even so, it was fun. I might make an instructable on it, but I need to find time to dissassemble and reassemble it.
CameronSS7 years ago
Attached is a picture of my dad's electric bike strapped into its custom carrier on the back of our electric Ford Courier. It uses a German-built motor, and three 12V SLA batteries in a rack under the frame. The bike is a BikeE recumbect, which is now a nonexistent company. So is the difference between brushless and standard DC motors analogous to the difference between fuel injection and carburetors?
Bike on Courier.jpg
Probably a good analogy. A carbeurator relies on physical phenomenon to adjust fuel/air ratios & delivery to the engine. A standard DC motor relies on physical brushes to transmit determine the position of the rotor and provide power in the right direction to the correct windings. A brushless motor relies on sensors to determine the motor location, then electronically adjusts the current direction in the different windings, much as a cam sensor and the car's computer determine the position of the pistons in the engine to control fuel delivery and quantity.