Electric Surf Board

Boats, Jet Skis, Kayaks etc., including hovercrafts
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bigbore   1 kW

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Re: Electric Surf Board

Post by bigbore » Jul 23 2018 10:04am

:D :D

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bigbore   1 kW

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Re: Electric Surf Board

Post by bigbore » Jul 23 2018 10:05am

:) :)
Last edited by bigbore on Jul 23 2018 10:08am, edited 1 time in total.

srn   1 W

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Re: Electric Surf Board

Post by srn » Jul 23 2018 12:09pm

bigbore wrote:
Jul 23 2018 10:03am
The water is generally drawn through the outlet nozzle with a radial outlet
How about salt water, sand and dirt ? Anyone who had problems with direct cooling from nozzle water ?

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bigbore   1 kW

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Re: Electric Surf Board

Post by bigbore » Jul 23 2018 1:32pm

srn wrote:
Jul 23 2018 12:09pm
bigbore wrote:
Jul 23 2018 10:03am
The water is generally drawn through the outlet nozzle with a radial outlet
How about salt water, sand and dirt ? Anyone who had problems with direct cooling from nozzle water ?
If you have sand or dirt sucked in the jet drive you will have bad problems with impeller far prior of cooling problems. I saw a Lampuga Boost stopped by a fisherman's line with a consequent replacement of both the stator and impeller.

Frizzo   10 mW

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Re: Electric Surf Board

Post by Frizzo » Jul 24 2018 7:11am

Hi Srn.

I would do it like in the image I attached you. For the dirt I would put a tank filter like the one used in nitro rc cars.

link: https://www.ebay.de/itm/L11517-1-5-Mas- ... Sw5cNYXTti

For the salt water: just clean after every use your cooling system by puming clean tab water in it.
Attachments
Unbenannt.png

fabianpusch   10 mW

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Re: Electric Surf Board

Post by fabianpusch » Jul 26 2018 2:47pm

In my board I have started to use the water going out from the nozzle/delivered by the jet.
But after a run there is a lot of heat remaining in the whole system.
So my next improvement will be an update with an additional cooling pump, a filter and a reed switch to switch on or off.
The f***ing heat is really a problem.
For a first step use a water bottle (PET), add a hole and put in a tube which fits into the outlet of the water.
So you have eliminated both together, the post cooling and the fresh water flushing of the system 🤪

Frizzo   10 mW

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Re: Electric Surf Board

Post by Frizzo » Jul 26 2018 3:10pm

Hi Fabian. Can you add some pictures of that bottle system? I kinda didn't understand what you men with that. :oops: :P

srn   1 W

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Re: Electric Surf Board

Post by srn » Aug 07 2018 3:32pm

Hello guys,
here some updates of my project:

Today I made first water tests in a small pool (after fixing all sealing issues last days).
It worked very well, also the water cooling, which I made according to Frizzo's suggestion.
IMG_3577.JPG
Here two log files of my controller. The peak current looks high, while the max power of 1,5kw at 6000rpm is quite moderate I think.
Controller 2 history 2018-08-07 21-33-45.jpg
Controller 2 history 2018-08-07 21-34-03.jpg
Tomorrow I will slowly increase the speed and check power consumption and efficiency.

fabianpusch   10 mW

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Re: Electric Surf Board

Post by fabianpusch » Aug 09 2018 12:37am

The graphs are definetely not good.
What about the voltage of the battery.
Normally I have 450/500 peaks when the engine ist running on 250A.
And the peaks are occuring only at the acceleration phase...please drive a ramp.
From 0-25-50-100 throttle Input.

srn   1 W

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Re: Electric Surf Board

Post by srn » Aug 09 2018 3:40pm

Hello Fabian,

do you know why this peaks can occur ? You see on following graph, that the average input current is 10 - 20 A.
Peak current is at motor side, maybe I have too fast acceleration ? I will reduce it and try again.
Controller 2 history 2018-08-09 22-32-24.jpg

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madin88   100 MW

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Re: Electric Surf Board

Post by madin88 » Aug 10 2018 1:02pm

If motor current is larger as the battery current by such a big factor (10A battery and 100A phase around 50s) than it's normally a sign of overload.
Is the size of the propeller correct and what about the motor kV? If you would use a motor with way too high kV it could look similar..
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srn   1 W

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Re: Electric Surf Board

Post by srn » Aug 10 2018 3:36pm

The Impeller should be too small (60mm) for the Lehner Torqstar 7050 275kV.

I found that there was high tension on the shaft. Will adjust it again and do another try.

Mgivens   1 µW

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Re: Electric Surf Board

Post by Mgivens » Aug 11 2018 3:40pm

Srn, I have a question about the torqstar. Did you remove the anodized purple color? Do you have a picture of it with the acrylic shield off? Thanks!

I have the same combo coming, torqstar 1 with the 60023 so very interested in seeing how you get your setup working without the peaks.

—Michael

srn   1 W

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Re: Electric Surf Board

Post by srn » Aug 11 2018 4:56pm

Hello Mgivens,
my motor looked already like this when i got it. I also wondered, because i expected black-purple. Dont know but i dont need color on it.
B11178D6-338A-43FA-9A85-EC61EC0FD1F7.jpeg

Mgivens   1 µW

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Re: Electric Surf Board

Post by Mgivens » Aug 11 2018 5:21pm

Thank you. That is strange that it is silver. Did you order directly from Lehner? The back looks different too, wonder if the design has changed...

srn   1 W

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Re: Electric Surf Board

Post by srn » Aug 12 2018 1:06am

Yes I ordered directly from Lehner, in april this year.

Frizzo   10 mW

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Re: Electric Surf Board

Post by Frizzo » Aug 12 2018 5:10am

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

srn   1 W

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Re: Electric Surf Board

Post by srn » Aug 12 2018 5:39am

Frizzo wrote:
Aug 12 2018 5:10am
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.

srn   1 W

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Re: Electric Surf Board

Post by srn » Aug 12 2018 6:39am

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.

fabianpusch   10 mW

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Re: Electric Surf Board

Post by fabianpusch » Aug 12 2018 1:31pm

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.

srn   1 W

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Re: Electric Surf Board

Post by srn » Aug 13 2018 1:52am

fabianpusch wrote:
Aug 12 2018 1:31pm
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" ?

Frizzo   10 mW

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Re: Electric Surf Board

Post by Frizzo » Aug 13 2018 3:42am

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...

fabianpusch   10 mW

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Re: Electric Surf Board

Post by fabianpusch » Aug 15 2018 1:03pm

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.

srn   1 W

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Re: Electric Surf Board

Post by srn » Aug 16 2018 4:14am

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 ?

fabianpusch   10 mW

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Re: Electric Surf Board

Post by fabianpusch » Aug 16 2018 2:52pm

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.

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