I just finished my first esk8 build however I don’t seem to be getting enough power to move me when I stand on the board and was hoping someone can help me trace down the problem.
Here is my setup:
12S6P battery park I made using Samsung 25R 18650 cells.
Twin motors, Turnigy Aerodrive SK3 - 6374-192KV
Flipsky Dual FSESC4.20 100A
2.4Ghz Mini remote Controller Built-in Lithium Battery
Gears, I have a 14 teeth motor to 66 teeth on 8" tires
Trampa board, trucks and pulley system being used.
The battery pack is balanced changed to 100%. I’ve checked the voltage getting delivered to the ESC and it’s 49.88V.
My remote is fully charged, I’ve done the setup using the VESC tool for the motors and remote input. When the board is in the air, throttling the remote spins both motors. Both blue and green LEDs on ESC board are on, so it’s powered on fine.
I have updated the Firmware on the VESC to use 5.0, 5.1
I’ve checked with my hands to make sure there is no slippage on the motor and pulley.
The signal from the controller is fine and coming in at 100% when setup with the VESC Tool.
What is your vesc settings, batt max and motor max?
What is your theoretical calculated top speed?
I ride on SINGLE 192KV SK3 with top speed around 47-51 km/h and motor max at 45amps on 12s. this results in 2kw power at 44.4volts. and its quite powerful. you have literally double that.
Man, i forgot to look at your settings. Take a look at your voltage cut offs. you have 12s. and cut off at 17volts. Vesc thinks you are with 0 charge ant its not giving you any power. Try to set it so every sell would be at 3.5 volts discharged(42v for 12s. and set cut off starts to 43v). and you gonna fill the power))
And one more. 80A double drive for this vesc is too high. and most important you dont need that power. Set it to 25-30A. and start with that. this would be very powerful. if not - try to slightly increase. And look at some vesc settings guides. looks like you need this. bad settings is unsafe and can damage your hardware
for the Samsung 25R the cell cut-off voltage is 2.5V as per spec. So I set it a bit higher to 2.8V per cell. For 12S this would give me a cutoff of 33.6V. The VESC tool guide says for dual VESC I need to divide this value in half as the value is per VESC. This is why my Cutoff voltage is set to 17v.
I don’t think the cutoff voltage is the reason why I don’t feel the power. I started with a higher value earlier, did do anything for me.
You’re right about my VESC, it’s rate for 50A per side, however the VESC tool was asking about my motor max current, which is 80A, so this is the value I used. I will change that to match the VESC which make more sense.
Well, voltage drops very fast from 3.5 to 2.5. Most of ht “juice” between 4.2 - 3.5. Setting cut off to 3.5 will prevent damage and your liions fill live much longer. Well, 3.5 is good for lipos, and liions maybe 3.2. But this will not influence distance… maybe 10% or so. you have plenty of range with 12s 6p. take my word for it, do not go below 3.3-3.5. Or check several articles about liions. you dont want to damage battery at very beginning. i treat my lipo same way and im riding in it since 2016. and do not store it fully charged more than 2 weeks
im sure that you have to divide when its about amps. Voltage is not divided by #vescs. So set voltage cut offs to “3.5 * number of cells”. for examlpe cut off starts at 43volts and cut off at 42. for each vesc. 17v is death for battery
motor max current is what you want to output, not what motor is rated. your vesc fill fry out in seconds. believe me). set it to 30a each. you will be surprised how much it is. its plenty of power and safe to vesc. in future if you gain experience, you can go higher maybe to 40 - 45a each - its HUGE number(4-5kw). 80a each is dath for you and vesc and everyone around. take my word for it
about cutoff. yes, you are right. this is not the reason - it can damage battery, but not take away power. lat me look again
im running in bldc, not foc. maybe some settings there. but im not sure - ask here https://forum.esk8.news.
what is your calculated top speed?
p.s.: battery regen 30 is too much. if ita on each vesc - its waaay to much. you will damage liions
pps: check https://forum.esk8.news and ask there. there are many people can help.
ppps: you made several mistakes than can damage vesc and batteries and you. do not rush. take several days to read stuff, watch videos and lean new stuff. you spend a lot of money on your build, do not rush.
thanks for the detailed reply, this is excellent information as I am still learning and the VESC tools is a bit confusing first time around.
I failed to catch that about only dividing the current in half and not the voltage, you are correct, it makes sense. I went with your suggested safer values and will worry about tweaking later.
You should try FOC, it is more quieter, smoother and efficient. I did try BLDC and it was really noisy. My top speed (weighted) is about 57.22 km/h.
So I do notice one thing, my board will not move on it’s own from a complete stop when I am on it. If I give it a nudge, then it seems to move and respond to the controller, otherwise I can hear the motor trying to turn over but it won’t. Is this normal? does this happen with your board.
Looks like something related to FOC settings(i have cheaper vesc and it my not work with it - im afraid to try to nut fry it). I really don’t know what it can be if its FOC.
On stand stop my board has lower torque - it doesnt like to accelerate from stand still, but it still does that. According to your top speed and similar configuration to mine, except you have 2 motors and top speed is 10km/h higher, you had to have very powerful acceleration from stand still. Its around 1.5 - 1.6 times more powerful than mine, and i treat mine as very powerful) (by the way, helmet is good idea for ultra powerful boards)
I think you have following options:
try BLDC to understand weather problem in FOC or not: rollback all settings to default, set specific settings to motor current, battery cutoff, motor regen (i beleve for such a big liion its around 10a, double check that). throttle settings, motor settings for bldc exc. If it runs fine, but too loud, than problem in foc - try to switch to foc and change settings with caution
Answering: “So I do notice one thing, my board will not move on it’s own from a complete stop when I am on it. If I give it a nudge, then it seems to move and respond to the controller, otherwise I can hear the motor trying to turn over but it won’t. Is this normal? does this happen with your board.”
No, it moves from stand still. looks like power is limited somewhere. where? good question. best guess so far is foc settings. as i said you have 2 options to understand weather this is the case or not
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!
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.
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.
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)
