I thought I should follow up here with a copy of the post I put out about this subject. Sorry it is duplicated elsewhere on Elias' build thread:
First off, I have gotten rid of all juddering, (totally gone) with my 60 V triangle and a full 50 amps of available current for my Bafang Ultra. Sounds easy, but I spent over 8 hours on this and must have tried reprogramming 50 times, always getting a com error at the end of the save function. I also tried a second cable, since I have two from Grin, no help. Finally, I figured that I somehow corrupted something internal to the PR so I figured out where and how to get the default off ES site, then imported it and the save parameter was successful without an error message. From there, I then kept trying to manually, on screen make the changes for judder elimination but EVERY time I saved it, there was a com error and after power cycling changes would disappear. Then I would have to reload the default by importing the XML file.. Finally a light bulb went off after hours of reading the forum, trial and error etc. So I manually made the changes on the screen, then I exported it to XML, THEN I imported it and save parameters worked, only that one time, but that was all I needed it to work.
I went out and test rode it this afternoon on my 15 mile Delta Loop (the shortest) and I cannot tell you how powerful this motor now feels. I have two standard Bafang Ultras on both 48 and 52 volts, 30 amps so I have a good measuring perspective and it is amazing. I put all the throttle output changes back to original settings. Here is what I got off one ES site post and it worked great for my 60 volt / 50 amp system with Ultra:
Feedback bandwidth tuning
Current regulator bandwidth Changed from 1000 rads to 0 rads
PLL bandwidth Changed from 1.00 Rads to 3.00 Rads
Torque down ramp to 1ms
Regen torque release ramp to 1ms
(not really sure these two changes are needed, but I am afraid to go back in and make changes because it works great the way it is.)
On Advanced page:
Current Regulator Kp to 1.0
Current Regulator Ki to 10
Speed Regulator Kp to 4.0
Speed Regulator Ki to 16.0
Then check the Enable access level 3 box and click save parameters.
One other thing I did, but would not recommend is setting the max field weakening current to 35 amps, it works and I am afraid to go in and try to change it! I am pretty sure this made a lot of the heat in the motor, but also a lot of the power!
Bike will run to 37/38mph on throttle only. In high pas assist and 10 gear I can get it to 43/44. with pedals and throttle, then I quit pedaling and keep throttle maxed and it stays over 40 for about 3 miles on throttle only.
This thing does get hot running on flat levies with 50 amp steady running thru it! I actually rode it this way with the cruise control on for about 6 straight miles on the levies today! I thought what the heck let’s check out heat buildup. Temps rose quite rapidly but not shockingly so. At 100C it started throttling back and eventually stabilized at just over 100C with current at 33/34 amps and speed at 32/33 mph. I was very happy with the temperature throttling function. Since I believe this function resides in the CA, I will be playing with it and fine tuning it.
Keep in mind ALL of this is on a loaner set of wheels and shifter I stole off another bike because my rear Rohloff and front DT Swiss H1700 wheels will not be here for another two weeks. I only have a front brake so far because I have to bleed the rear one and I let the Local bike shop do all the bleeding. Within one month I will be looking for a high end 72 volt high capacity battery with smart 60 amp BMS so we can find out how well the Ultra handles 4000 watts. So far I feel like I could fine tune the temperature throttling function and add a heat sink to the controller and this 3000 watt system would not take any special care to keep it running. The protection functions seem to do the job. Time will tell if the Bafang can hang at this power range for the long run, daily rider.
I do know the I can play with the throttle ramping to get a little harder hit if I think I need to. Right now I am just happy that I can even start in 10th gear from a dead stop without ANY juddering!
As for the frame, it felt rock solid... I think Frey made a great frame and it is pretty darn strong.
