Haha, no need to be sorry, I know I appreciate that you took the time to actually do these tests, and I’d expect a lot of other people appreciate it as well! The only reason I asked was because the VESC is the last component I need to order, and I was eager to find out if this one is actually good enough for my purposes. It sounds like it’s more than good enough!
As for the anti-spark (I’m new to these things), but is that what’s built in to the ‘smart switch’ LED button that the dual comes with? I also have a switch built in to my bestech BMS, so I’m not too sure which of these switches I should be using and which is better to bypass. I guess I could always wire up both…
I would start of by bypassing the besttech bms and use the integrated one on the Dual 4.2 plus vesc if you go for that unit. because the antispark on the 4.20 plus also got room to start auto off and all that stuff which is nice, and when/if that thing blows up you could always bypass the unit and use the Besttech unit instead. (that would require some soldering work though, will update when I have a little video on how to to that in the future, need some help from the smarter man on how to do so exactly so I don’t mess stuff up)
I would maybe wait before I have tested out the cutout thing tomorrow or until @Gamer43 has confirmed that the 22ohms resistors are the correct ones to use.
@Schtekarsten 22 ohm should be the working value. The actual value would be 23.5 or 24 ohm, but if two ohms really makes that much of a difference I’m going to reeeeee out of this forum (If that’s the case, hopefully flipsky won’t be too annoyed they have to change the resistor value a second time).
Putting MOSFETs in parallel slightly alters the parasitic characteristics, but for all intents and purposes it can be treated as a single MOSFET with corresponding electrical characteristics.
We are actually cutting it real close with the dead time insertion, I’m still worried some units with higher gate charge might have issues with shoot-through. I need to figure out how to pull request the vesc firmware and push a version with 600nS of dead time instead of the default 360nS.
@chrischo1996 any chance you could provide more details on when the cutouts are occurring? Things like current and other parameters would be very helpful in determining the cause. Also what app settings are you using (positive ramping time).
I believe on a previous ride, you said you encountered no cutouts, what changed between that ride and the one you began to experience cutouts with?
I’m not with my board at the moment so this is all off the top of my head, I’m fairly certain they’re accurate though.
Battery Max: 20A.
Battery Min: -10A.
Motor Max: 65A.
Motor min: -30A.
App settings:
Throttle curve: -10% for both accel and braking.
Positive ramping time: 0.30s
Cutouts happened only when I slammed on the throttle to drag race my friends. I went through everything and rechecked all the connections and found a slightly loose bullet connector between the VESC and the motor, it was pulled out less than 1/4" inch. I plugged that back in and taped it up and haven’t had cutouts since, so that may have been the problem. I’d like to do more testing before I reach a confident conclusion though.
I’ve had similar problems with loose connectors. Let us know how your tests go, thanks! If you still get cutouts under hard throttle or braking, try a positive ramping time of 0.5s or 0.8s and see if that helps.
Question for you - I’m looking to make a 3D printed enclosure for the VESC (which I don’t have yet, so I’m having to make the draft using photos and online spec sheets). The problem I have is that I need screw mounting holes in order to bolt the vesc to the enclosure bottom, as I do not want to use glue or sticky tape.
However it seems that the heatsink isn’t using bolt-through standoffs but instead some other kind of standoff with a threaded bottom half. I was wondering if it would be possible to remove these standoffs, and replace them with bolt-through ones like these? - LINK
Figured as you have the vesc to hand it would be easy enough to find out for me (if you don’t mind?). Means I can keep making my plans and drafting my 3D model.
Edit: If you could also tell me the height of the standoff (the gap between the pcb and the heatsink), as well as the bolt size they’re using? I’m guessing it’s M2 or M3.
I bought my 4.20 dual back in August, and after the cut out fix was announced spoke to Flipsky and they were happy to swap it for me
Im just waiting on the replacement revised unit to land.
I had to pay shipping both ways, which for me in the UK was a total of around £25, which i was happy to pay for a working unit as id most certainly make a balls up of trying to solder the fix
I think I know whats wrong with your ESC and it is salvagable. If you still have it could you probe across all three motor phases and see if any of them are a short to the positive rail or ground?
If my hunch is right, a pair of MOSFETs need to be replaced. If not, then it would probably be the drv8302.
but thank you!
