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Thread: Questions About 200A (or more) Brushless ESCs

  1. #11
    That's it! ESR. Few manufacturers seemed to put it as a figure on their spec sheets if I remember right in which case, don't bother with those caps.

  2. #12
    Quote Originally Posted by TechAUmNu View Post
    You want low ESR caps like these: https://www.digikey.co.uk/products/e...s=UPW1J681MHD6
    I have a huge bag of them if you want me to send you some.

    They need to be as close to the esc battery input as possible for them to have much effect.
    Cheers, might take you up on that if I do get the ESC.

  3. #13
    IMG_20161129_204136.jpg

    Its not the best picture but here on the left you can see there are 4 wires connected to the VESC. The larger 2 go to the battery, the slightly smaller 2 go to a set of 3 1800uF 63V caps. These helped smooth out the power delivery to the VESC and reduce any spike loadings on the batteries; one of the reasons why CnS accelerate so quickly is because the VESC's get the power as soon as they want it.
    This is probably as close as you can get them to the board besides them being physically wired to the board itself, so this is what you are aiming for. I would over spec on voltage just to be on the safe side; so if you are 24V, go 36, something like that, and you want as much capacity as you can get away with; within reason.

  4. #14
    Quote Originally Posted by Eventorizon View Post
    IMG_20161129_204136.jpg

    Its not the best picture but here on the left you can see there are 4 wires connected to the VESC. The larger 2 go to the battery, the slightly smaller 2 go to a set of 3 1800uF 63V caps. These helped smooth out the power delivery to the VESC and reduce any spike loadings on the batteries; one of the reasons why CnS accelerate so quickly is because the VESC's get the power as soon as they want it.
    This is probably as close as you can get them to the board besides them being physically wired to the board itself, so this is what you are aiming for. I would over spec on voltage just to be on the safe side; so if you are 24V, go 36, something like that, and you want as much capacity as you can get away with; within reason.
    Still managed to blow up two of them even with those caps...

  5. #15
    caps.jpgThis is a bit overkill I think.

  6. #16
    Quote Originally Posted by TechAUmNu View Post
    Still managed to blow up two of them even with those caps...
    These are the modified VESC's designed by Rory Mangles of Team Nuts; uprated FETs, Caps and a variety of other tweaks that I can't remember. We are also only driving around 60Kg max on hours which probably helps even if the motors a 3770W Continuous.

  7. #17
    Yeah, experience tells me rotomaxes and VESCs don't mix too well in combat...

  8. #18
    Quote Originally Posted by Eventorizon View Post
    These are the modified VESC's designed by Rory Mangles of Team Nuts; uprated FETs, Caps and a variety of other tweaks that I can't remember. We are also only driving around 60Kg max on hours which probably helps even if the motors a 3770W Continuous.
    Yeah that's the ones I blew the DRV chip on three of them. Managed to replace one but we switched to the VESC-X and haven't had a single problem with them. Even at 80A 8s with 80,000 erpm

  9. #19
    Quote Originally Posted by TechAUmNu View Post
    Yeah that's the ones I blew the DRV chip on three of them. Managed to replace one but we switched to the VESC-X and haven't had a single problem with them. Even at 80A 8s with 80,000 erpm
    We were at 80A, 12S, 80'000 ERPM on the MVESC's. I think the weight makes a difference (60kg not 110 as mentioned before), and the quality of the Scorpions could play a factor too. I would be willing to bet there is some significant variation in the consistency of a Rotomax and other cheaper motors. They may pack a lot of power but i think that is partly their undoing when it comes to being drive motors. I have no evidence as such to back that up, purely anecdotal, but it was a dodgy Rotomax that kept killing Pulsars VESC's.

  10. #20
    Actually not quite true. A motor seemed to consistently take out various SimonK-flashed ESCs in series 2. In series 1 (when I ran VESCs) it was the Mangled VESCs having the wrong (50v) ceramic caps and overrunning the eRPM limit pretty badly that made them die.

    It's basically impossible to run 28p motors on current-gen VESCs reliably unless they're extremely low KV or you undervolt.

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