Brushless 350W Motor Stuttering and Screaming - New Build

[flyingbeekeeper]

Just installed a new motor and controller. Found the right phase combo, Wide open throttle draw at .8 Amps, minor noise on startup. But when going 15-20mph and I hit the throttle hard, the motor makes a terrible NOISE (pedestrians will turn their heads at the sound), chokes, suddenly gets restistive and drags, and stutters. Amp draw at this time is 5-15. This is on a flat part of road. However on the hill to my home, I will be going slower and drawing 20 amps with no stutter-NOISE drama.

Backstory- Sadly, I thought it time to retire my old Wilderness Energy brushed motor that I installed 10 years ago. Thought I'd replace it with a 350W motor and a 22A 9-Fet Brainpower controller. I was going to use my CA to limit the amps to something reasonable.

I loved that old Wilderness motor, quiet as a mouse, could take 30A but it wasn't efficient and it refused to die to make an upgrade an easy choice. I've built a mid drive in the mean time. This is my first try with a brushless, maybe I'm missing something simple.

So I bought a 350W front hub a few years ago anticipating the death of my Wilderness motor, I think I bought a geared one. The controller I got last month. 5 pin halls on motor, 5 pin halls on controller. Left the halls static ie. plugged together, tried the 6 different phase connections. Found the false positives phase connections, and the correct positive with 0.8A WOT. Used the self learn pins to confirm, unplugged when done.

Ideas?
My suspects-
Throttle voltages out of spec
Speed restriction built in? (not supported by WOT conditions)
Bad hall sensor?

 

[amberwolf]

Some geared hubs spin so fast (inside, pre-gearing) that some controllers can't keep up, called ERPM. This seems more likely as the problem appears to be described as happening at faster speeds than 15mph, and not at slower than 15mph.

Sometimes it is a hall signal problem, interference from phase currents in the wires under load (is fine with no load). In these cases sometimes adding a small 0.1uf capacitor from each signal to ground at the controller hall connector can fix it; sometimes just separating the hall wires from the phase wires starting at the axle exit and keeping them separate all the way to the controller fixes it. (or adding a metal shield around the halls and grounding it only at the controller end)

Some hubs are just noisy, or a combination of a specific controller and hub are noisy. Sometimes a sinewave controller fixes that, if not using one already. (some sine controllers default to trap mode instead, if there is any troulbe reading a hall signal, so they work fine until there is enough of load to cause a problem, for instance).

These are both less likely for the same reason as the first one is more.

If the ocntroller has self-learn that usually finds the right combo on it's own, and doesn't need any manual wiring. But it's probably not a combo problem because it works fine at high loads at slower speeds.


If the motor actually drags, then it probably isn't a geared hub, as those typically have freewheeling clutches on those gears. Or something is wrong with the clutch. If the hub is a freewheeling geared hub, it will be hard to manually spin backwards, but easy to spin forwards.

If it is a nonfreewheeling geared hub it will be just as hard to manually spin either way.

If it is a DD hub it will be pretty easy to manually spin either way, and the same in both directions.

 

[motomech]

Sounds like a phase prob to me.
I've had a number of small geared motors where the colored wires didn't match the controller wires. They would run static, or actually take off smoothly, but as soon as the throttle was nailed, they would screech and fall on their faces. Lacking the tester machine, I would map-out every combo of phase wires on a sheet of paper and try them all. Since I always change out the crappy white nylon connector, I would leave the wires bare and test the combos with wire-nuts. Murphy's law assured me it would be the last combo that would be the right one. But still, it would only take me a 1/2 hr.
Talking about the connector, if you have a wht. nylon one, make sure one of the little pins didn't get pushed out when making the connection.

 

[dogman dan]

Yeah, I think its the rpm and the no halls controller. You need to connect the ones you have.

you found the right order for the phases to run it no halls, now just find the right halls combo and you are off to the races. Start of course, by trying the same colors combo that worked on the phases.

If you get totally stumped, buy a self learning controller.

 

[motomech]

Yes, I forgot to mention the Halls.
I would hook them up the same as the phase wires.

 

[pullin-gs]

Put controller into sensorless mode and see if it will spin motor cleanly. If it works, your hall sense connections are wrong or controller hall circuit is not working.