Brushless motor experts...

[Npdp72]

Hi,
I wonder if there's someone out there who really knows there stuff when it comes to how brushless motors and sensored ESCs work?

I had an issue racing last night where intermittently the car would lose top end speed on the straight, sometime it would really fly down the straight as it should but every few laps it would be really sluggish, it felt almost as if the ESC had gone into a safety mode and was only giving 50% throttle, but then it would come back to normal for a few laps. Throttle control though the infield still felt reasonably good.

I was running a new Hobbywing V3.1 ESC for the first time with my normal Speed Passion 6.5T motor.

At the end of the A final when I took off the shell I found the yellow B wire for the motor had popped off! I had finished the race in a fairly respectable 5th place, had not retired because of the wire coming off.

So, my question is would a loose connection on the B motor wire cause this kind of symptom?

I would have expected the motor to not run at all with just the A and C wires making contact. Is it possible for the motor to still run reasonably well with just the two wires?
If so, can anyone explain the theory to me?
If not, then I am still looking for the cause of the problem, any suggestions?

Finally is it likely that running on the two wires would have caused any permanent damage to ESC or motor?

Thanks,
Nigel

[pugs]

Originally Posted by Npdp72

Hi,
I wonder if there's someone out there who really knows there stuff when it comes to how brushless motors and sensored ESCs work?

I had an issue racing last night where intermittently the car would lose top end speed on the straight, sometime it would really fly down the straight as it should but every few laps it would be really sluggish, it felt almost as if the ESC had gone into a safety mode and was only giving 50% throttle, but then it would come back to normal for a few laps. Throttle control though the infield still felt reasonably good.

I was running a new Hobbywing V3.1 ESC for the first time with my normal Speed Passion 6.5T motor.

At the end of the A final when I took off the shell I found the yellow B wire for the motor had popped off! I had finished the race in a fairly respectable 5th place, had not retired because of the wire coming off.

So, my question is would a loose connection on the B motor wire cause this kind of symptom?

I would have expected the motor to not run at all with just the A and C wires making contact. Is it possible for the motor to still run reasonably well with just the two wires?
If so, can anyone explain the theory to me?
If not, then I am still looking for the cause of the problem, any suggestions?

Finally is it likely that running on the two wires would have caused any permanent damage to ESC or motor?

Thanks,
Nigel

Hi Nigel, if the car was moving then it is possible it would continue to move with only 2 wires on....it would be slower and I would have thought stuttering as well...if the car had come to a standstill I would not imagine it would set off again with only 2 wires. I dont think this would cause any real damage just it would not run as well, it could maybe generate a little more heat in the speedo and motor.....

The other thing to look at would be sensor lead as the hobbywing/ speed passion will run without the sensor lead but the motor is slower and always seems a little more "laggy" than when using it with the sensor lead in place

[danielc3009]

Hi Nigel

I've had that problem before with the speed passion motors. The wire came off due to a poor contact on the motor cause the connection to heat up. Check the plugs if they pull off easily then replace all three of the springs on the motor contacts.

To replace them you'll need some male 3.5mm bullet connectors and carefully remove the springs without bending them. Then remove the back plate off the motor and the old springs, then push the new springs on the pins.

The best way to do this is clamp the donor connector in a vice pointing up and open the spring slightly with a small screwdriver and slide it up off the end of the connector. Then holding the with the pins pointing up push the springs down onto the pins.

I hope that make sense. I can post some pictures if you that will help

[MattW]

Yeah that sounds feasable, as you would be missing one (of 3) "coil fires" if it stopped on the coil that wasn't firing, then it wouldn't restart, but if it didn't fire, then went passed it (as it was moving) it would be picked up again.

I suspect the laps where it was ok it was making some kind of contact on that otherwise missing phase.

[neallewis]

Speedpassion motors. does it have the push on connectors?
After some use, these get worn and dirty and build up a resistance, and with that come heat as the current flows to the motor coils.

Solution is to use a motor that has a directly soldered wire from ESC to motor contact, rather than a push on connector. If careful you can solder up the push-on connectors for a better contact.

[mattr]

I've had exactly the same issue, with exactly the same symptoms.

the motor and ESC are still both in use. as long as the loose wire doesn't short anything out, there's no reason why it should be damaged.

[imull]

http://www.atmel.com/images/doc7827.pdf

This is a document from Atmel describing how to design a brushless speed controller, the basics for the motor control at the start of the document provide good explanation of operation.

[neallewis]

https://www.youtube.com/watch?v=ZAY5JInyHXY


https://www.youtube.com/watch?v=WyQInXjpGwU

[Npdp72]

Thanks for all the replies guys.

Lots of useful information and comments.