Electric Surf Board

Frizzo said:
Hi Srn,
With what battery configuration did you go btw?

Hello Frizzo,

I am currently using the Turnigy Heavy Duty 4S 5Ah Lipos. They are rated with 60C (120C burst).
At least for testing they do a good job. Have them in 2S2P now.
 
Here my graph after adjusting shaft and reducing system voltage from 60V to 30V.

Controller 2 history 2018-08-12 13-34-59.jpg

The peaks are still very high. I am also wondering about the input request. Seems that my remote control is only sending 0 or 100%.
Will check this before next try.
 
Really strange picture.
I think you are right with the remote input, seems to be 0 or 100%.
What about your cable lengths?
Do you use additional caps.
About settings, try to increase the acceleration time...to 3 or more seconds.
Next use a servo tester as input and check everything again.
 
fabianpusch said:
Really strange picture.
I think you are right with the remote input, seems to be 0 or 100%.
What about your cable lengths?
Do you use additional caps.
About settings, try to increase the acceleration time...to 3 or more seconds.
Next use a servo tester as input and check everything again.

Hello Fabian,

I am not using additional caps.
The cables from ESC to batteries are not longer than 30cm. Cables from ESC to Motor approx. 80cm.
Can the peak current at the motor occur because of too long battery cable ?
I understood that the current between battery and ESC is the "input current" ?
 
30 cm seems quite long to me. Did you also twist the battery to esc cabels? Can´t see it in the pic of your board.
Maybe that could help already solving a bit of the mistery...
 
30cm is not too long.
Try some additional caps (from MGM) or similar specs.
I have cable lengths of 80cm...
I think it could be a problem of the maximum voltage. I had to reduce from 15S to 14S.
 
I already reduced voltage to 8S which did not make any difference.

The MGM controller is tracking the "input current" and the "peak current". I thought that the Battery to ESC current is the "input current" ?? This one is very stable so if I am right, there is currently no need of capacitors or shorter cables. (please correct me if I am wrong)

The "peak current" = "Peak current flowing through the phases (the controller and motor) in the PWM motor pulse".
Following this definition in the MGM manual the peaks occur due to too high motor resistance ?
 
Due to high motor resistance or a bad battery = high resistance in OHM.
The input current isn't the issue.
That was the reason why I switched to the LiFePo4 and now LiPos and no toy battery from HK.
 
Today I tested my 3D printed jetdrive. Could not do any measurements, but gives a lot of power.

https://youtu.be/NewKjySw2ko
 
Hello toto44,

good video, looks like a lot of thrust for this small motor. Do you have a log of motor/esc power during this run ?
 
Hello,

i changed my carbon impeller to a 3D-printed steel impeller. It is really impressive quality and less vibration.


today I will make first measurements of power consumption. Will provide results later.
 
srn said:
Hello,

i changed my carbon impeller to a 3D-printed steel impeller. It is really impressive quality and less vibration.
how much did it cost?
 
madin88 said:
how much did it cost?

I ordered a 62x62mm. They said that it will shrink 2-3% after thermal treatment and finally I got a 60.5 x 60.5 impeller.
It is ~95€.
 
toto44 said:
Hello SRN

what pitch does your impeller have? Did you balance it?

Hello toto,

the pitch is 60mm or equal to D if you scale it.

I have not balanced it yet.
 
srn said:
Hello,

i changed my carbon impeller to a 3D-printed steel impeller. It is really impressive quality and less vibration.
IMG_3664.jpg

today I will make first measurements of power consumption. Will provide results later.

How much did it cost you to 3d print in metal?
 
ropower86 said:
How much did it cost you to 3d print in metal?

I ordered a 62x62mm. They said that it will shrink 2-3% after thermal treatment and finally I got a 60.5 x 60.5 impeller.
It is ~95€.
 
hello guys,

i am still testing in my small pool.
now my remote control is working fine. Also the new propeller is doing a very good job.

here my current MGM log. I wonder that I have really small power consumption at 10.000 rpm. At the moment I limited the MGM to 10k rpm for testing. Will try 12k rpm in a bigger pool soon.

Controller 2 history 2018-09-05 18-34-39.png
 
Hi
are you sure that there is really load on the system?
It seems to be really a too low power consumption.
Could be an issue of water mixen with air, less stress for the motor to handle / put through your jet...
On the other side, try to accelerate up to 14000, and measure the pulling force.
 
Hello, about electric surfboards, and more specifically to buy one. What do you think of these https:// awakeboards.com, is it worth investing?
 
It is absolutely clear, you have an issue with a mixture of water and air.
Normally you should have during ramp up by 10000 rpm something between 120-160 Amps.
 
I see we all went ghost on this post :lol: :pancake: . It seems like we all figured it all out. I will be testing soon, in the fiberglassing stage then Gel coat. I will be making a mold and start producing DIY jetboards if things go well with my new design. :bolt:
 
That Sounds really nice...
Now I am a little curious :D
Show some pics please to reanimate this old and dusty thing....
 
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