VESC Braking (release)

Not using BMS.

Whatever is occurring is a response from the VESC.

If it’s overcharge I’m not too worried as peak will be for a matter of seconds. I’ll get some data next week and work out peak A under normal braking.

I’d rather protect my life stopping reliably than the life of the batteries

Thanks for replies - will post results soon.

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OK - I think I know what’s been going on

VESC was configured when GT2B controller was in original housing I then rehoused inners into a Badwolf enclosure.

I’d cut away part of the Badwolf trigger guard to allow for better movement, this increased the range of the brake – BLDC pulse width range is now between 0.58 and 2 – previously 1 and 2.

I expect when braking in range of 0.58 and 1 without correct configuration caused brakes to fail.

When reconfigured to range of 0.5 and 2 the motor span when controller trigger in rest position – this, I believe, is because the new trigger movement range is biased to brake - 2/3rd brake 1/3 drive and VESC rest position is midpoint.

Solution - install a brake stop for trigger on badwolf enclosure and return pulse width range to between 1 and 2.

If I’m an idiot and have missed something obvious please let me know.

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@dogeatgod I have the same problem occasionally when braking in FOC mode. I also use a gt2b with the badwolf mod. I’ll do some tests to see if it happens only when my battery is fully charged. If it is the case that the regen from braking is exceeding one of VESC’s protective thresholds, then it seems like the solution would be to modify braking force or the regen settings.

Your solution of limiting the trigger swing might solve the issue, since you would not be able to reach the max brake. But it seems like having access to the full range of motion of the trigger would give us more precision in braking.

It’s also possible that when you moved the gt2b into your badwolf case, you might have inadvertently moved the throttle trim dial. This could explain the new min and max pulsewidth settings for PPM.

I used a square of medium density foam as a trigger stop, this returned range to as before, and everything is tickity-boo.

Previously cut outs occurred regardless of battery charge or incrementally increasing regen settings, up to Motor -55 / Battery -30.

Adjustments were made to throttle trim – this kept the same pulse width range just moved pulse width band (max and min pulse width changed / range remained same)

I’ve a spare GT2B so could revert back and look for differences but as I’ve solved my issue it seems a little pointless, that is, unless others would find the information useful.

Please let me know how you get on.

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I just finished my build on Saturday with GT2b to BadWolf v2 case and had the brakes cut out on a hill. Kinda scary at the moment you need brakes.

@dogeatgod I did some testing this weekend. Here’s what I found: if I’m moving at a slow speed, and I push the brake trigger a little too hard, I can reliably trigger the VESC to shutdown and reboot.

The same thing happened when I was using a nunchuck, but it is less problematic and easier to control with the GT2B. But it still should be fixed!

My hypothesis is that the the amount of incoming energy from the motor during braking\regen is exceeding the threshold set in BLDC Tool, so the vesc shuts down to protect itself. I am running a pretty high reduction ratio of 14:60, so that may contribute (the motor spins faster than a typical eskate while coasting and braking). I don’t think this is related to max battery capacity settings, because it happens even when the battery is half depleted.

Anyone with more VESC experience have thoughts about this? @chaka @elkick ? I’m not exactly sure which setting should be modified, but I’m thinking it is “motor min” and “batt min” per this thread by @onloop.

If I’m careful with the brake (i.e. I don’t push it too hard) I can safely ride as it is, but it would be better to dial in the settings so that it less likely to happen.

I’m going to try reducing the braking force to see if it plays better with the pulse width min of GT2B. Will report back.

BTW - the shutdown\restart only happens at very slow speeds or a stop. If I pushed the brake trigger at a high speed I get belt skipping or I get tossed off!

Do you have the same issue in BLDC mode ?

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There may be something out of kilter with your VESC settings or controller set up – if you can share your set up (motor/battery), VESC battery/motor regen information and min/max pulse width for RC that would be useful.
Hopefully it will be an easy fix, like mine.

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@trbt555 good question; I will test it again, but I don’t recall experiencing this in BLDC mode. However, I don’t want to switch away from FOC mode. I love the smooth starts and the quiet operation.

You’re in the right place @FLATLINEcustoms, we’re trying to figure this out as well!

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Are you on 2.16? If not, give it a try, FOC motor detection seems to be better now. Also, is breaking on -20? What’s happening when you go lower?

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Just imagine how easy this kind of troubleshooting will get once @jacobbloy finishes the Android BLDC app !

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Thanks @elkick I’m on 2.15, so I’ll apply the new firmware and try again. I haven’t modified the breaking force from default yet; that might be the fix! I’ll let everyone know.

As a side note; I feel like a useful addition to BLDC Tool would be inputs for battery voltage and capacity that would work with the PPM or nunchuck inputs to help users figure out whether cutoff thresholds should be modified. It doesn’t seem like it would be very hard to add, and it would be a major help as people start using VESC in higher volume. You only need to experience one cutoff to know that it is pants-shittingly scary to have your ESC reboot unexpectedly. Who is friends with Vedder? @jacobbloy don’t you work with him directly? Maybe we can share this idea?

There’s a “feature request” section on Vedder’s forum.

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@treenutter thank you for update.

When you push the brake trigger too hard do you mean quickly or to extremity of trigger movement?

How quickly does the VESC reset? If I took the brake off and reapplied, braking kicked back in, a delay of a second or so onlyfor trigger movement, if I pushed movement too far braking would drop out again.

I’m running 14:44 – just for information.

“If I’m careful with the brake (i.e. I don’t push it too hard) I can safely ride as it is, but it would be better to dial in the settings so that it less likely to happen.” – when emergency braking is required it’s tricky to remain careful with the brake. I almost went under a car when riding with my braking issue, something went askew between brain, careful and trigger finger.

Reducing motor min made braking stronger but problem remained. I didn’t take batt min as far as I could but the incremental reduction that was made didn’t make a difference.

“BTW - the shutdown\restart only happens at very slow speeds or a stop. If I pushed the brake trigger at a high speed I get belt skipping or I get tossed off!” – just to be clear ‘tossed off’ means being thrown from the board? Or is this a form of extreme boarding.

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@elkick just for total clarity; when people say “lower” with the negative brake force values, everyone means that we are going further from zero, right?

Example: moving from -20 to -30 would mean LESS brake force.

With less I meant -15 or so. -30 will apply more.

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@dogeatgod

It could be either. I really notice it at slow speed when i push the trigger too far. I think of “hard” braking as a combination of trigger extremity and trigger movement speed. So, braking too hard can force a reboot, and braking too fast can also do it.

It takes about 1-2 seconds to reboot and then come back to life. Not very long, but long enough that it can cause trouble during a ride!

I mean that the board might stop\reduce speed while my body is still accelerating, so I fall off of it. This was more due to my own bad riding… I was getting used to the braking and applied it too hard.