Why do speed sensors go bad?

[Fairtax4me]

A factory motor spins about 4,000 rpm and the sensor counts 8 pulses for every single one of those revolutions.
It’s basically a couple of transistors which are essentially electrical switches. On - off as the magnetic field passes by. So at speed the sensor counts approximately 32,000 pulses in one minute of normal operation. Eventually that $0.30 transistor is going to give up the ghost after counting a couple billion pulses over the course of several years.

Electrical interference can also cause damage to small electronic components.
Heat cycling also takes it’s toll on everything eventually.
The sensor is next to a constantly alternating magnetic field that gets hot when it’s working and cools off when it stops. Sit overnight, repeat.

[mgray70]

Originally Posted by R&TBabich

There's always a reason.

Wires fray, corrosion creates resistance, components overheat, contacts corrode, etc.

Has anyone opened one up?

How does the sensor work - mechanical, magnetic?

A mechanical sensor could wear out.

A magnetic sensor should last a long time.

I know there is always a reason, but I understood his point. Is there anything he could do to prevent it, and the answer is no other than getting a quality replacement. If there was something we could do I'm sure there would be plenty of threads about it.

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[Mooncarter]

Originally Posted by mgray70

I know there is always a reason, but I understood his point. Is there anything he could do to prevent it, and the answer is no other than getting a quality replacement. If there was something we could do I'm sure there would be plenty of threads about it.

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[R&TBabich]

Originally Posted by mgray70

.... the answer is no other than getting a quality replacement. ....

Is there a physical difference to look for in a quality replacement versus a repro?
The MCOR 4 is easy to tell with the China versus Mexico ITW Switches stickers/case.
.

[mgray70]

The best way is to call Dave at Revolution. Site sponsor. He only sales OEM Club Car I think.

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[Fairtax4me]

Originally Posted by mgray70

The best way is to call Dave at Revolution. Site sponsor. He only sales OEM Club Car I think.

Per David, the real ones have a Green wire. The cheapo ones have a Blue wire.
David only sells the real deal.

[movin-on]

Most of the cheapo ones on fleabay have a green wire...

[Sergio]

The speed sensor only has a single chip that costs less than $2 inside, no other parts.

https://www.digikey.com/product-deta...012-ND/1006587

My speculation is that Club Car is unique in that it powers its speed sensor with 15v while other manufacturers that use the same motor and speed sensor only use 5v.

There are many grades (voltage rating) of the hall effect chip available and not all of them can tolerate 15v.

Since most Chinese products lack any kind of quality control or proper traceable identification, it is possible that some of those are great sensors but just not designed to operate at 15v.

Vibration and heat from the motor, including armature shaft and bearings can affect the life of the sensor.

If You store the cart for more than a week You probably should also place the cart in Tow since there is a 50% chance the hall effect would be in a latched state (low level) which creates internal heat.

Also, the 8-pole magnet generates 4 pulses per revolution since the sensor is bi-polar meaning it takes one pole to go into high state and a pole with the reverse polarity to bring it to a low state (one high and one low state makes a complete pulse).

[R&TBabich]

Originally Posted by Sergio

.... If You store the cart for more than a week You probably should also place the cart in Tow since there is a 50% chance the hall effect would be in a latched state (low level) which creates internal heat. ....

The controller gets a power signal from the Tow/Run switch and the Key Switch.
Does the sensor continue to get power with just the Tow/Run input?

[Sergio]

Turning the key switch OFF does not disable the speed sensor since the Controller still has walkaway brake with the Tow switch in Run.

The cart needs to be in Tow for the speed sensor to be powered off.