You need power and voltage for rpm ( speed), sag is a problem
I will only set limit to the battery amp to see what it does : motor max to 300A , battery max to 150A , then 180A , then 200A… you will directly see if the top speed will increase because at this point I think that Is not the motor that limits
The motor probably heat up as well and it’s resistance may increase , and it needs to be with in 5% for a correct run , so you can run motor detection when hot to see the new value …Or try with + 5% in value
How do we authenticate breaking the speed record? If @Flying_Rodeo owns it at 58 KM/h, then how was that proven? I’m not doubting it, but @jakebarnhill1 showed some nice evidence in his YouTube video. I’ve read 54 & 58 about @Flying_Rodeo.
Just curious as it will undoubtedly be a point of contention at some point, on who actually holds the record. Seems like there should be some guidelines…
Thanks @Giga that clears it up a bit. So is the VESC’s displayed battery current not very accurate compared to the motor current? and what is the calculation you use to work out what the motor current is from the peak motor current displayed?
@Alexandre not sure how much of a change in resistance is needed to really throw off how the VESC can handle the motor but I think there is a setting in the VESC software that slightly increases the resistance value as current goes up or something like that. Maybe it could have something to do with why it would lose sync before increasing the observer gain…
@noahark This is a good point, I guess it should be proven by at least 2 accurate GPS speed runs to be truly accurate. If someone is claiming 60kph based off the speedometer of a jet ski they are riding next to you probably wouldn’t trust it .
You can’t really use a GPS because of the accuracy (especially if it’s on your phone in the hatch) and because it doesn’t take into account water current flow.
For the most accurate speed in water, you use a paddle wheel like the perfect pass boat systems. That removes the water current flow immediately. But that’s not ideal either as it would add a little drag.
The best way to measure accurate speed would be a timed run between 2 points on a non-tidal lake. Pretty much the same way they do all the records.
Managed to get a quick data ride in this evening on 16S, I didn’t get a chance to go for a second run and try keep it at full duty cycle for longer.
The data shows that the battery is sagging down to 3.1v/cell and it was fully charged, the max motor current looked like it was briefly at 245A but was sitting at 225A when at full duty cycle once the voltage sagged… anyway here’s the vid, probably a good thing I ended up wearing a full face helmet when I couldn’t find the normal bike helmet I normally wear with the GoPro.
It does change them a bit! I guess its acting more like a good 14S pack. It sort of doesn’t make sense though because unloaded at 50v it should be getting 25000rpm if is exactly 500KV and in the vid it was doing 24333rpm, so the motor isn’t dropping much in rpm. Very interesting.
Yeah it doesn’t seem to fully add up. I think this VESC less volts than it actually is. When I started the VESC was showing 65.5v (not shown in the video), the battery was 67.2v as it was fully charged and I have checked it with a multimeter when fully charged before and it is normally close to 67.2, so assume the VESC is displaying the voltage as 1.7v less than it actually is, that could make it a bit more realistic.
I think it might be worth adding an external voltage and current meter to the system. That way it can be accurately calibrated. I’m sure there is even a GPS based option online somewhere…
But its good as this highlights the inaccuracy that the VESC and Metr system has and can be fed back in and used to improve it.
@foilmore I hit the sand river bed that’s what caused it to rip off. Yeah it really doesn’t take much of an object to throw you off with the delicate balance of the foil
The cells get warm but not too bad. I don’t really have the tools to measure the ir accurately but would be good to know compared to when it was new. The pack has a lot of cycles on it now after 2 years of efoiling. It used to be a 12S.
With more and more people interested in the record attempt, we shouldn’t be very far from seeing the first footstraps on efoil boards for this reason as Kitefoilers and Windsurfers do. Esurfers have them too. In the meantime, a leash connected to the board nose could help.
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