[HELP] Weak braking on VESC

I am having issue with extremely weak braking on my setup. I’m using 2x Flipsky 6354 190kV geared at 15:36 with 90mm wheels. It is powered using an esk8supply Dual VESC and 10s3p 30Q battery (BMS bypassed for discharge).

The issue:
when I’m traveling at a higher speed (>10mph), and need to break the breaks are extremely weak until I get under roughly 5mph and then they get ridiculously powerful (like belt slipping powerful). I’ve tried changing a bunch of settings incl negative ramp time, motor negative current, battery min etc. BMS is also bypassed so there should be nothing stopping the regen current.

Screenshots of my settings:

Any help would be appreciated.

Things to note:

  • PPM negative ramp time changed to 0.10s from 0.20s
  • Haven’t changed battery regeneration current since I think -6A per side is pretty high already for a 10s3p 30Q battery.
  • I’ve changed the throttle curve significantly and tried multiple combinations but that doesn’t help since I don’t think that’s the problem.

For brakes you can run like 40% of the continuous discharge since it’s only for a moment, try 12A per side

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okay, that makes sense, I’ll try that and let you know how it goes.

You need higher regen. Regen is high speed braking

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In Motor Settings > General > Current, decrease “Battery Current Max Regen” from -6A to -12A.

Do that for both ESCs.

You can try -17A if that’s not strong enough.

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Got it, thanks so much guys @b264 @annihil8ted . That was always my first thought but I didn’t wanna damage the battery. I’ll give it a shot and lyk

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What would be the max on regen for 30Q’s per cell?

I know the max fast charge rate is 4A, so I set mine according to that info, but when I am reading this I feel like setting it higher.

4A I believe is sustained charging. During a brake, it’s such a short period, you can set it to be higher than that. Say 6A per cell

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Continuous long-period charging limit is 4A per cell but for brief braking you can exceed that, even by a lot. Because it’s brief.

I would not freeze a mostly-drained battery and then skitch on the back of a car, in the winter, braking trying to charge your pack. That can damage the cells.

Normal skating and braking with a battery that’s not frozen (Even using throttle in sub-zero temperatures heats up the battery into the safe zone) won’t damage the cells.

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People don’t realize but the most wonderful thing about lithium ion batteries compared to lead acid is there technically isn’t a limit of how much current you can dump into the cell or realistically take out.

You’re simply limited by temperature and lifespan of the cell.

All the cell ratings and spec sheets are simply a sheet of how the cell will perform in most circumstances. Take the 30q for example which is a spec’d 15A discharge cell that can do 25A with a temp cutoff no problemo.

Sure sag and other things definetly come into play, but if you wanted to you could dump 100A into a single 30Q and it probably wouldn’t blow up, for a few seconds.

For a community that is so against running discharge BMS’s its awfully interesting people run such conservative battery regen Amps…

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updated

it’s pouring outside rn so can’t test it now, but I will give it a shot tomorrow!

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Ok.

That’s not what that means to me :crazy_face:

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haha after the board is all waterproofed I will ride it through a lake

You use those mounts I sent you? Pictures?

Wrap it in a trash bag and go. It’ll be fiiiiine.

yesss, thanks for the hookup!!

here you go: (still needs some mods to make it look nicer)

also I’ve never been the guy to post my build since they don’t always end up great so just fyi this isn’t my first build/mod but it looks a little fucked because I still gotta fix some stuff on it.

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Ohh that’s purdy

I didn’t think anyone else used those wheel pulleys. Where did you get them? Hobbyking has been out of stock for a while now.

haha yeah the wheel pulleys are sick! I borrowed them from my friend (I think they’re from Trampa) until my kegels come in so I can use the 110s!

Your motors are uneven lol. Looks good though lol.

haha yeah gotta fix em

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