Ok well… I will do this mod when I have to open the enclosure again… What about all those horror stories of fried VESCs because of the FOC Mode ? is this an urban myth ?
no, they are true. But many are related to user error…
Do the mod, flash some new firmware (important) and at first set up everything pretty conservatively. If you stick to single-vesc put some heatsinks on the FETS and DRV.
if it works keep increasing the Amp-ratings.
Thanks for the offer… I now already did the mod… I had those caps laying around because I wanted to do the mod anyway some time soon… just was afraid of FOC mode… so I will test ride it now… wish me luck
It seems however when spinning and braking it up that the FOC mode has weaker brakes, is that possible ?
Apparently it is due to the newest braking algorithms on 3.XX FW. Try Acks 3.100 FW, he has maintained the braking of the older 2.18 version.
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Just went for a test ride… Acceleration and Braking feel perfect with FOC… FOC feels like it has a lot more torque. I love this mode… however… even though its now night and it’s cold outside - the motor got pretty hot. I even hit the Motor Temp limit again! It feels like it’s getting hotter than in BLDC mode almost ? Any clues… I would really like to keep the FOC mode because of the good response
Edit: The Test ride was with 20khz… will test 30khz tomorrow
Hey,
sorry to hear about your heat problems, as @bevilacqua mentioned I use the same motors in 150kv on my MTB with 12s and had no problems so far (and I’m not nice to this motors). Right now I’m waiting for a replacement motor because I crushed one but will monitor the temperature in warm weather end of next week.
To point out the positive, imagine your motor wouldn’t have a temperature sensor then your vesc wouldn’t reduce the power because of temp limit and could harm it.
There is one thing I recognized, your idler pulley is on the wrong side, it should be on the slack side. Everytime you accelerate you put it under strain. I don’t know this mount but it looks like you could simply rotate the motor plate 180 degrees, then the idler is on top.
When your motor gets hot, touch the motor pulley and idler, too for comparison. Is one hotter? Also not all bearings are made for higher rpm and can heat up quickly, the smaller, the faster.
Did you tried it without idler pulley as well?
Which FW are you running right now? Last year I experienced also differences with different FW’s. I tried 3 and with one FW a motor got sizzling hot while the other just got warm.
But can’t tell you further technical or electrical details because I’m no engineer (well yes I’m audio engineer but that doesn’t help 
)
You could also post some screenshots of your settings, maybe there is something wrong.
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Question, did you measured the motor temperature or are you reading the value that on VESC tool?
Hey Rich… I am pretty sure the idler pulley is on the correct side (slack side) Looking at the motor pulley - the motor will turn clockwise and my idler is on the top so it’s correct
In this example the motor is turning counter clockwise and it’s on the bottom…
The Idler pulley and the belt don’t get hot at all. Without idler pulley the belt will easily skip.
I am running the 3.101 Ackmaniac firmware.
Will try again today when it’s getting warmer again
The motor temperature is measured using the VESC Monitor App. However when touching it it does not feel as hot as it is showing in the app…
Everything you say is correct if the motor is regular mounted before the wheel. In your case the motor is back-mounted that’s why it’s exactly the opposite 
Which temperature shows the app before riding? It could be that there is something wrong with your temp sensor. Especially when you say it feels colder, when you hit the 75 degrees can you still touch the motor?
Sorry I still don’t get why the side it is mounted should matter… The direction the pulley is turning should be the key point. In the picture that you posted… imagine the motor pulley LEFT… turning into CLOCKWISE rotation. Then the idler pulley is in fact correct 
Before riding it will not show anything… shortly after starting it will be around 35-40°C
I just made this pic for easier understanding:
Drive direction in both examples is to the left. When you accelerate (marked in green) then you have the biggest force there (that’s why it’s better to have the idler on the slack side). Dependent of the position of the motor the slack side is on top or bottom.
Hope that helps 
BTW I don’t think no more that it has something to do with the heat issue but the idler is still on the wrong side.
Yes… I understand… But my Idler pulley is on the slack side 
Just look at the picture… the Pulley is PULLING the belt from the left side (wheel) to the right side.
That means that the Slack side (PUSHING) is on the bottom.
I just looked at the temp when turning it on and only spinning it very slowly… the Temp readings look plausible… so the sensor should be ok
This is too funny 
Your red arrow shows the direction when riding backward but not forward. If you have front wheel drive you’re right but I guess it’s back wheel drive.
Move your longboard and watch the direction in which the belt moves.
Actually it is showing the direction to go forward. Looking at the above picture the FRONT is on the RIGHT side… the Board is on the TOP of the picture. If you turn the wheel clockwise the board will go FORWARD. My Motor is mounted on the FRONT of the board.
I am sorry but if you still think that the idler pulley is on the wrong side then further discussion will not help at this point - in my opinion it is correct.
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Ok, never thought about that then of course you are totally right 
!
But hopefully this off topic discussion can help someone else to understand it.
Wish you can solve your heat problem soon, the data you’ve posted looks normal to me.
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Ok… just had my first crash at around 35 km/h… Here is what has happened…
I was testing the new FOC Mode with 30 khz… still the temperature got up quite easily. So I was accelerating a little bit faster so my Body was shifting to the front to counteract the acceleration and then suddenly the board stopped (not sure if it braked or just stopped accelerating).
I flew off the board straight forward directly onto my chest dragging for a couple of meters… Remote control and board flew off to the left side.
After being able to catch my breath again I slowly went back home. This is a serious safety concern now - I will try another motor or anything… but I have to do something… I can’t take the risk of Cutoffs while accelerating… Luckily its only torn apart clothes and bloody arms…
That sucks. Do you still have warranty on that motor? I doubt it’s related to your setup. You’ve tried just about everything.
Go with an open design motor.
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