Just how SMOOTH should a direct drive motor run...?

e-troll

1 mW
Joined
Jun 29, 2013
Messages
15
Is some slight roughness (not in power deliver) that kind of feels like a bad bearing normal for direct drive motors. Is this cogging torque? I replaced bearings and hall sensors are all good (power delivery is smooth. No jerks or anything). I only just finished this build and it is the only e-bike I have every ridden so I have nothing to compare too. At speeds over 20 everything is super smooth. When I give it power at lower speeds I feel this roughness. It is a higher wind motor (does 32 mph on 48V 1000W). I believe higher winds are less smooth at lower speeds? Am I being OCD or is something wrong with my motor?
 
I was guessing you mean jerking or fluctuations or something like that, but it's still pretty unclear, I could assume what you mean, but it would probably be better if you stated. Please define rough. Maybe, if words fail you, a video would help a lot. Have you compared and watched the motor with no load? Do you have a cycleanalyst or watt meter of some kind?
 
I think you have a bad problem. It's either a bad connection in your wiring, or you have the halls in the wrong order. Running with a false positive halls and phase wires order can ruin motors and contorllers.

If the order is wrong, it usually shows as drawing too much power when spinning no load WOT.
 
The other possibility is a sensorless controller that is not programmed correctly, but Dogman's probably right sounds like a hall problem. If a DD hub motor is being driven by a properly programmed controller and solid power source it should run smooth as silk especially with no load.
 
Thinking some more, maybe he's just commenting on normal motor grunting at start up. Motors switch on and off the phases, and under heavy load controller and motors can vibrate and make some noise. That's normal, but some motors and some controllers rattle more than others.

If it's a real harsh chatter, that's more something wrong. A bad connection on the phases can cause chatter when drawing lots of watts, then run smooth as silk when it's only 200w. Usually if this is your problem, you eventually melt the connector housing, and go, "oh, it was that."
 
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