Google this query.
do smartphones use acceleromter to improve gps speed accuracy
Accelerometers can help smooth/estimate motion between GPS updates, but they do not reliably improve true speed accuracy for sports timing on their own.
Why not?
An accelerometer measures all acceleration forces, including:
- actual forward/backward acceleration
- tilt/rotation of the phone
- vibration/chop/water impacts
- rider/body movement
- gravity (unless perfectly compensated)
That makes it very noisy for something like eFoiling/kiteboarding.
I do not think its generally unreliable for GPS speed.
If you take a longer track and measure the speed over a longer period, its pretty good.
Phone in car will also have a pretty strong smoothing on the data.
The issue is just max speed, where only one or a few data points are used.
This can vary a lot and your max speed will then be simply one, where the errors results in the highest speed.
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Also when it comes to 65220 motors, guys be extremely careful when it comes to the wires.
They are using a silicone that is extremely prone to fatigue, I just noticed on a sample that i cut that i have a few cracks after a few extreme bending tests. On my setup efoil i managed to do sort of a stress-relief mechanism but I’m noticing this wont be enough if someone pulls the wires too much or they get trapped and squeezed.
Two months, 10h of riding passed and no issues found. Im at 115 motor max and 165A motor max, no FW upgrade done on the VESC.
At 120A motor and 160A abs max i got one cut off going over abs max while going full speed and it was nasty 
The sea is warm already therefore my max temp ESC reached 34 degrees in peak heatwave on Croatian coastline.
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For my cables, I bought a meter of heat-shrink tubing and covered them with it for added safety. I applied liquid rubber (silicone-type) where the cables exit the motor, and I did the same for the hole in the PETG motor mount—filling it completely with the liquid rubber.
With 65220 they advise me as configuration of the attached photo:
110
-50
230
False (abs)
In your opinion is it ok with a 13s 10p 21700 tenpower 40XG 45A, 40ah.
Is correct ? @HOF
So with 13S you will have more current than I but i guess thats fine. Your screenshot is not the same as the configuration you want.
I would stick with my settings. Flipsky recommends lower values so I am already pushing it a bit but I still feel it is safe and high performant.
EDIT: Also, slow ABS will have to be enabled - I tried without it but it just cuts so so randomly that its not drivable. Also, do not upgrade the FW.
EDIT 2: During my drives I tested a lot of different propellers and found out that two bladed ones are the best choice for this motor since it is not as strong as the 65161. The reason behind the lack of power is the ESC that we need to limit. What I found out is that with three blades the starts are painful, the motor current goes to the max while with two bladed propellers it is more in sync with the battery current, also feels better. At the end, with my settings, I reached peak 4,2kW.
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Very kind! Yes the screenshot is the default one I set this:
110
-50
230
True (abs) (you notice!)
My only concern is could the 200A fuse blow?
Can I ask what kind of propeller you’re using? Do you have an STL file? I have the standard white three-blade one, but right now the setup is mounted on a tow boogie so I can test everything out.
Keep it True - do not worry about the warnings on the VESC program - thats how some flipskys esc work
200A fuse, where? If its on the battery then dont worry, you will never reach this current, not even close. Also most of fuses this big are slow to pop.
Propeller: The original metal three bladed one should be fine for a boogie I would say but its far from the best, especially not suitable for an efoils. I cant share the STLs, not my product, but i can tell that propellerkings 2bladed one is fine 
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Yes, I installed a 200A Mega fuse right before the QS8 anti-spark connector; I’m spending so much time on this—I have a million doubts!
If you want to print a two blade propeller you can try this one: 🚁 Flipsky 65161 2 Blade Propeller for E-Foil・Free STL File for 3D printing・Cults
I have it on one of my efoil masts and it works well. Seems a bit less efficient than the three blade flightboard prop, but I still like it. It was made by @kevintran
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