Which Flipsky FSESC 4.xx for ebike build


I have a Bosch Gen1 ebike with pedal assist up to 45km/h (no throttle, only pedal assist). The motor is 36V sensorless and draws max 18A. It is crank driven (mid drive) and when pedaling at 100 RPM, the motor turns at 2900 RPM. The motor has 9 pairs of poles so I guess the max eRPM should be around 2900 x 9 = 26100, let’s round it up to 30000 eRPM, which is well within what a VESC can achieve.

I’d like to ditch the proprietary motor controller and replace it with VESC such as a Flipsky 4.20 single or Flipsky 4.12 single (coupled with an Arduino to convert pedal assist signal into a throttle signal). I do intend to run the motor at max 20A in BLDC sensorless mode (would probably not risk FOC) using a 10S Li-ion battery so I figured out a VESC 6 based controller would be overkill and VESC 4 are cheaper.

I like the form factor of the Flipsky 4.20 single and the fact it comes with heatsink (which makes it easy to mount it anywhere) but I read some mixed reviews on the 4.20 in general (comes with smaller caps than 4.12, has cutouts etc). The cutouts have been supposedly fixed by upgraded resistors so it should no longer be an issue I guess.

For my modest application, would the 4.20 do or is it better to go with the 4.12? Since this is a rather low power application for the VESC, I’m mostly interested in reliability. According to a video made by Flipsky, the 4.20 handles better and can draw 35A continuous (thanks to heatsink) while the 4.12 throttles at 25A. On the other hand, I’m a little worried by the smaller caps on the 4.20 (3x220uF vs 3x680uF on the 4.12) since on an ebike, the battery cables are usually longer than on an electric skateboard…

Which one of the 4.20 or 4.12 should I pick for my application? Any reason to stick with the 4.12 now that the resistors on the 4.20 has been updated and that it seems to handle heat better than 4.12? Is the relibility of the 4.20 any better o worse thn 4.12 if max current is 20A?

Am I correct that VESC6 based controller would be overkill here?

Since there is no regen on this ebike (mid drive), is it okay to set battery current max to 20A and battery current max regen to 0A in VESC-Tool (instead of a negative number)? And use the same numbers for Motor current max and motor current max brake?

Thanks for your insights!

You can try tb6. Much more reliable than a flipsky… id rather have too much than not enough…

TB6 is certainly nice but I’m located in Europe and shipping is prohibitive: TB6 is 135$ + 60$ shipping, which makes it close to the Trampa VESC 6. Compare it with a 45-50$ (incl. shipping!) for either a 4.20 or 4.12 from Flipsky… I’d be happy to get the TB4.12 instead of Flipsky’s one if shipping to Europe was priced lower.

I understand that Flipsky is regarded here as a budget fairly low quality brand but I’d have thought that running a 4.20 or 4.12 at max 20A, max 30000 eRPM, BLDC mode and using a 10S battery would be adequate for reliability. Also, with such parameters, wouldn’t a VESC6 be totally wasted? I mean VESC6 is supposed to be better than VESC4 for higher loads and to run FOC reliably because of the 3 shunts. If I draw only 20A max and use BLDC mode, what would a VESC6 bring me over a VESC4?