davidswelt

I have installed a kit that includes the Greenergia (YCSVxxx) controller and a 500W Bafang front hub motor.
The single power setting controls both throttle and pedal assist response.
However, even on the lowest power setting, the motor responds so jerky and harsh when I start to pedal at low speeds. The result is somewhere between awful and downright dangerous. I basically just went on one test ride yesterday and found I could use the brake levers as a workaround (to disable the motor when pedaling slowly). Obviously that is not what I want going forward.

The controller seems to be un-programmable. Are there any settings I can access, perhaps with a different display? Do I need to replace the controller entirely?

Chuckles1

If you have a throttle, use that at low speeds and when starting from a stop. Start pedalling in level 1 only after you are in your lane and moving, so when pedal assist kicks in, it's not so dramatic. Throttle allows you to apply as little power as you want. I use it for all low speed maneuvering, at intersections etc.

andychrist

That’s the same front hub setup I have on my dual drive ecumbent, only mine came from Bluenergia rather than Greenergia. Haven’t experienced an identical problem but never installed the PAS sensors, use [half twist] throttles only, which work fine at any speed and assist level. Issue I do have is that the XT-60 connectors on all the extensions leading to the batteries are crappy, so often lose power and the motor shuts off. Also seems to be a loose connection on the XT-60 leads inside the controller itself because one time when the system seemed dead, after checking all the other connections on the battery cables, I pushed the wires going into the controller case further back in and the display lit up again. Then I could re-enter my passcode and everything seemed okay — at least for the while. Haven’t been back on that bike since then because of a broken spoke so can’t speak long term.

BTW did you go into the Advanced settings menu by entering the passcode 1919 and selecting all the parameters corresponding to your setup such as battery voltage and wheel size?

Also, found this review of the Greenergia controller on Amazon, wonder whether it might be applicable to your situation:

“I had planned to replace my controller with this supposed compatible bafang controller.
I put it on my ebike and it worked, kinda!
Speed was low, and motor was sluggish, and the speed was not registering.
I open the controller, to find out that the hall effect sensor wire was cut near the entry of the wire inside the case, and was not connected. Don’t know if it was on purpose or if it was a factory flaw.
So the motor could not give the controller it’s speed and was not working correctly.
Since I didn’t [have] the schematics of the controller, I could not use it and I trashed it.
Was very disappointed.”

davidswelt

Thanks for your reply, andychrist, though it appears you do not have the problem I asked for.
I did go into the extra menu. I will experiment some more, I guess.

You are right that speed sensing should have to do with it. The controller should match power output to current speed when reacting to the pedal-assist sensor. That said, the speed displays correctly on the display, so I'm thinking the controller must have the correct speed. I fear the controller is just poorly designed...

davidswelt

Chuckles1: This, or start pedaling with the brake lever pulled slightly to disable the motor. Neither solution comes natural do me as a cyclist...

andychrist

Actually David I think Chuckles nailed it. Bafang’s PAS sensor functions more like an on/off switch and is notoriously poor at syncing with the rider’s cadence, while its throttle performs well independent of such factors. How does the Bafang work with the PAS sensor unplugged and using just the throttle?

davidswelt

It works perfectly fine with the throttle. In fact, I've been riding it for 200km without the PAS sensor installed.
The problem is that I'd like to have smooth pedal assist.
I'm not convinced it's a problem with the Bafang sensor (12 magnets) or the motor. It's just that the controller isn't smart enough. Granted, the controller does not know what gear we're in, and basically, it's not a torque sensor. Maybe that is what's needed...

davidswelt

I did some more experimenting. Changing the wheel size of course changes the speed that the controller (or the display) calculates.
However, there is no change in PAS response.

It is not correct to think of it as a on/off response, though. Pedaling slowly means much less motor input.

Which brings me to another idea: Maybe I can just set it to a higher gear, say, 4/8 instead of 1/8, to get more "measured" power?

KPREN

David go out there and pedal a really fast cadence. If the power is relatively smooth at a real fast cadence they you very likely have something wrong with the PAS disk and not the hall sensor pickup. If its just as bad or throwing error faults then its likely the hall sensor pickup. its possible that its in the controller but not as likely.

davidswelt

At higher speeds it's relatively good. As I mentioned earlier -- in higher gear it is also more natural even when slow. Basically, the system is tuned for a high gear ratio. The controller does not seem to take speed into account at all

(I do not think there is anything wrong with the disc. The diagnostic LED behaves predictably for all of the 12 magnets.)

2old

Really surprised reading this thread considering the vast number of motors Bafang produces in a year (probably 1,000,000+). I have three BBS02's (I realize a mid-drive is a totally different animal) with RPM sensors and all perform extremely well. Either the problem is a function of the square wave controller (not as smooth starts as a sine wave AFAIK) or yours is defective.