How far can you mod a 28mm (9C Clone) DD HUb?

[dogman dan]

Looks real fun. I liked having some holes directly over the windings. Just one 3/8 inch hole there will allow you to see the condition of your windings.

Nice thing about vent holes, is the motor will cool faster after the run. The real heat is the first 2 min after you stop, if you didn't do a cool down run for a mile. And it will cool down run better too, once you back down to 1000w or so.

450F is the hottest I ever got one. Flames shot out the holes. Track racing with one flat tire, 120v, 33 amps. So I was really slow in the corners.

FWIW, all that one got was fat wire to the axle stub. The stock wire can carry quite a bit of current for 6 inches. That wire was fine when I pulled it out of the flamed hubs axle.

 

[teslanv]

Gotta put the 28mm MXUS to use, until such time as it's big daddy gets here (MXUS 3Kw V2 3T).

For this 9X7T Wind, I'm going with 20S LiPo & 50A Battery current for 3600W total power.

What phase current is safe for a 9-strand winding? 80A?

 

[John in CR]

Gotta put the 28mm MXUS to use, until such time as it's big daddy gets here (MXUS 3Kw V2 3T).

For this 9X7T Wind, I'm going with 20S LiPo & 50A Battery current for 3600W total power.

What phase current is safe for a 9-strand winding? 80A?

My 9C 9x7 has a phase-to-phase resistance of 0.192 ohm, so at 80A it would make over 1200W of heat. Also, Justin tested the 9C 9x7 and if I remember correctly he said saturation started at 70A. I wouldn't push mine that hard even though it's ventilated, but mine need to be able to handle big loads up long hills so I'm forced to run motors conservatively. eg I run HubMonster at extreme power, but it has 1/12th the resistance of my 9x7 and I run it at only 5 times the current limits you're talking about, and HubMonster only sees max current for very brief periods.

It's so usage dependent that there is no correct answer to your question.

 

[dogman dan]

I've melted those motors several times running 40 amps of 20s. But the usage was hard, go brake, go brake, track riding or off road. Off road I could get away with it fine all winter, then one fine spring day I'd kill another motor.

I tend to tell people wanting to run them on the street at 40 mph, to carry no more than 10 ah, then they will run out about the time the windings start to stink from frying the varnish. Around 10 miles or so street riding WOT.

Better you vent it the farther you can go, this advice is for unvented or poorly vented motors.

 

[gogo]

If we work backwards from the 70A saturation parameter with a common controller's 2.5X phase current multiplier, we get 28A as the max battery amp draw needed.

Remember though, that the 70A will only be available to be delivered while the controller is limiting at 40% or less duty cycle. This means you will have increasingly less than 70A as your speed increases beyond 40% of no-load. Also, 70A will quickly heat the coils, so any load which drags you down to 40% of no-load speed while WOT is putting you in a dangerous zone, or regime. On flat terrain the 70A might only be drawn during acceleration, so the coils wouldn't have much time to build up heat. A hill that keeps you from attaining more than 40% no-load speed while WOT can fry your motor if sustained long enough.

Even half of no-load speed can send a still dangerous 56 phase amps to the motor.

Most common controllers have some sort of algorithm that prevents the full 2.5X phase current at very low speeds, or duty cycles. It would be interesting to see the actual output graphs for them.

If I had a controller with temperature cut-back, or at least a temperature gauge on the motor, I'd want to have a 70A capable battery and the battery current equal to the phase current in the controller settings. That way I could have the full 'no saturation' torque available from the motor to use at my discretion. I'd make sure to have a no-load speed high enough that the BEMF wouldn't prevent me from drawing 70A at whatever top speed I want.

 

[ebikedelight]

any updates on your experiment with the 1000 watt yescomusa motor running with hi voltage/ amps ?

also, was it easy to replace that hubs stock bearings ?

 

[Punx0r]

I have a Goldenmotor rather than yescomusa 9C clone, but replacing the bearings was very easy. The only ones tapped out with a drift and the new ones fitted by heating the cover in the oven to approx. 100°C and the new bearings just dropped into place. The bearings themselves were a common industrial size and about £2 each.

 

[wesnewell]

Every yescomusa motor I've bought were either oem GM's or GM clones, not 9C clones. They all had GM part numbers on them. AFAIK, 28mm 9C are rated for 600W while the yescomusa GM's are rated for 1000W. Someone reported the yescom 1000W motors has 33mm magnets, But I've never had mine open after 15K miles running 24 lipo on it since June 2012, and 18s on it the year before. I've not seen the newer model solid black yescomusa motor up close, so couldn't say.