Believe me or not and forgive me if this is a repost of information but I frequently speak with Vendors (Both friends and clients) so in addition I speak with many Chinese attempting to procure the best revisions of everything and to at minimum ensure we don't get a version with a known issue (IE: 750w version 1.0 had 6 FET issues and perhaps some minor issues we knew nothing about.
Then came patch 1.01:
This patch was done by dealers using Bafang Protocol 1.0 software (ControllerST written in delphi from way back, who uses Delphi even Visual Delphi anymore?) which many if not most of us have already, I've had since before Legrand Cruise but was NDA hence my project to reverse engineer the serial protocol and create the codebase opensource for all to benefit but before I could get 30% done the software was leaked but not by me so no more need for open source.
Please not the version 1.0 protocol was for this x1 BBS-01 - 6FET version
Next Came version 2.0, the 9FET unit
Surprise, new bafang protocol was 2.0 for the changes they made to take advantage of the 9FET setup - mind you overheating even at legitimate 25a and 48v was still an issue but it seems more a gearing and rider issue at this point *(Correctable with shift point indicator).
Then I believe it was Paul aka Cell_Man who figured out how to replace the ring gears, why? because the existing ones using now v2 software had a gearing issue so he offered a much needed aftermarket a solution, combined with claims under warranty (which only US Vendors with Reputable Chinese vendors were able to obtain).
So then emerges the v3 unit which was fantastic, no real controller issues (used within spec and geared properly, the latter they have yet to offer customer materials which focus on this but in truth these aren't supposed to be end user kits but installed by trained professionals or at least very experienced non professionals but whom know what they are doing and then some.
Guess what the issue with v3 became? Bearings! Yep somehow they figured out their bearings were failing (not an issue with v1,2,3) but introduced when gearing was fixed.
Software version for those internal controllers? Simple, can you guess - yep 3.0
Finally I became aware from a small vendor overseas (not alibaba or BMS battery related in any way) who at first handnt believed me, or wanted to) so he had just received an order of 50 units, 35 of which were states bound the rest all over. He broke the first one out (we were skyping) and loaded up the new Controller ST and guess what - v4 drives.
Since then ( a few weeks ago ) he's been pushing it as hard as the stock controller with some removed throttle delay / ramp setting for nearly 200 miles with no temperature or other issues at 15S or 55.5v.
No grinding, play, overheating or well.... no issues at all.
Moral of the story, for the least amount of headaches... ensure your vendor has v4 drives, which we currently do not as they are about to set sail but if you can't find one in the next 3-6 weeks, contact me via PM I will be glad to reserve one for you.
My costs are higher (because I didn't jump at the first POS vendor crap offered to me).
I should have batteries more than capable of powering these full tilt BBS-02 750 v4 units available shortly too, just arguing with the US Manfuacturer over Cell Type to be used to ensure weight, long life and rapid charge ability.
Hope that helps clear some of these cheaper kits up for people, in the end they may be fine for you but why risk it.
2010 Dahon Jack - GNG v1 - LYEN 6FET - 20/40A - 18S2P10AH - Nom:66.6v,1332w
2004 Hard Rock Pro Disc - Recumpence ms eDrive v4 - Astro 3220 4T - 12S2P16AH - HV110 - Left Side Drive - Gearing: 38mph
Nominal Peak Power @ 60 seconds: 5328 watts - Maximum Power: 49.8v, 120A, 5872w
2010 Downtube 8FH - Stock GNG v1 Stock Controller - EB809XC - 12-16S
2012 Downtube Nova 7spd - Stock GNG v2 - 12S2P10AH - EB809 - 12S-16S - 20A/30A,Nom VCC: 44.4, 888w