Not enough power to move me

ESK8 Electronics
9

Hi,

thanks again for all your help, really appreciate it!

I did try BLDC, it was too noisy and no improvement in power / acceleration. I have been in talks with Flipsky and they ask me to create a video for them to help out. I was told that me having no hall sensor is not the problem.

I am disappointed that with the battery pack I built and twin motors I can’t accelerate from stop to go. I don’t plan to ride until Flipsky get backs to me with a solution.

As for safety, I am very mindful of this. I am shopping for a full face helmet and also the usual knee/elbow pads and gloves.

As for the FOC, look more into it, I don’t think you will fry the ESC. The BLDC sends triangle waves, whereas FOC sends sine waves. Here is the description from the VESC Tool help:

BLDC

Trapezoidal commutation mode for PMSM motors.

FOC

Field Oriented Control (FOC) for PMSM (or BLDC) motors. The motor is commutated with sine waves instead of a trapezoidal waveform as is the case for BLDC commutation. FOC runs the motors more quietly (especially at low speed and high load), is slightly more efficient and provides automatic optimal timing.

I guess now I need to make a video and go over my build showing Flipsky measurements and VESC tool setting, the girl I am in contact seems very helpful and responsive!

10

Good luck

Thanks, ill try foc in future)

11

So I figure out my problem, only by fluke! When I slam my remote to 100% my VESC was causing the motor to stall.

If I just ease into it, the board will move from a complete stop and then slamming the remote to 100% doesn’t stall the motors. I am so glad my board is working fine, was going to give up of not having a working board. I even re-solder some of my XT90 connection and was going to rip everything apart and start all over.

12

“Absolute Maximum Current” is way too low, increase it to 150A {or more if it will let you}.

That’s most likely the issue.

Also go over the the motor advanced tab and lower fault timeout to 85ms

13

My motors are top rated for 80A, so even a bust current to 150A will damage the motors. However my VESC is 50A per side, burst 150A.

The VESC is tripping at 50A, when I set max to 45A, it is pretty good with the occasional trip, and 40A per side is super stable.

14

It will not.

The VESC is faulting because you have absolute maximum current set way too low.

If you raise it, you will thank me later. Those are only current transients measured over milliseconds and have little to nothing to do with oversaturating your stator.

Please note the difference between “Maximum Current” and “Absolute Maximum Current” – that second one you want at 150A or more. The first one, you can use your motor’s rating.

Enjoy :slight_smile:

2 Likes
15

If you do want to keep “Absolute Maximum Current” at 80A, then lower “Maximum Current” to something like 30A to stop the cutouts.

1 Like
16

Bro, listen to b264 here. He knows this shit backwards and forwards.

2 Likes
17

That is what I did, I set Absolute Max Current to 80A and Max current to 45A.

18

Those aren’t the same numbers

19

Too low.

Also too low.

Why bother building a battery that can do higher discharge if you’re not going to utilise it?

20

This is also too low, you really, really, really don’t want to go below 3.0V/cell and probably not even under 3.2V/cell if you want your pack to last any length of time. You’re only adding a very very very very minimal amount of range anyway as it drops off a cliff when it gets that low, and at a very very high price (drastically reducing pack lifetime)

2 Likes
21

Hi I tired higher setting and they keep tripping the VESC.

As I said, what seems to be stable and working for me is, after several trials:

  • 45A Motor max
  • 80A ABS Motor max
  • 100A Battery max

I did update my Voltage cutoff, @OleksiiF had suggested safe cell value also.

I went with 3.5V per cell for cut off voltage (start) and 3.2V per cell (stop).

Thanks for the tip on reducing the fault timeout.

With my new settings and I think this is due to having a sensorless motor, if I push the remote throttle too quick to 100% it will trip, however if I push it 1/3 way to get the board moving, everything is fine and then I can punch it too 100% and the VESC will not trip.

22

Absolute maximum current is way too low here, you want it like 150A

23

Thanks made the correction.

I have a question on FOC Setup. It is necessary that I remove my motors from their pulley and wheel? I’ve been doing it with everything hooked up.

1 Like
24

some say it is better with it off but no, don’t have to.

25

Nope :slight_smile:

1 Like
26

2.5v is extremely low for Li-ion batteries. That’s some advertisement often done by manufacturers to help you damage your battery quickly. If you want your battery to last, 3.3v lowest and 4.1v charged. 4.2v charged is also not good because of regen. constantly overcharging your battery. cutoff start and end cannot be divided by 2 for two VESC. Each vesc needs to know it has to start reducing power when the battery voltage is at 43v or so. The only thing you divide by two is battery max current. because each VESC will suck power from the same battery so they need to only need half. Motor current also too high. I think that running the setup wizard is better here because it sets all these values automatically. You have a pretty big battery, your range will be fine, no need of low cutoff voltage

2 Likes
27

I confused myself about dividing the voltage and current in half and initially divided both. Makes sense to only divide the current.

All the talk about the current dropping off a cliff, the graphs and where to set cut off finally clicked. I just overlooked the basics as I’ve been learning with my first build and setup.

I didn’t consider regen and was charging my cell to 4.2v will will charge to 4.1v/cell to make sure my battery pack has a long life.

What is a safe level for the cell to set the regen value to? I set my to 10A which I guess is for the entire pack.

28

-20A for a single drive or -12A + -12A for a dual drive is somewhere around what you want.