Volker’s Build - 80100 18650-30Q

EFOIL.builders Builds
52

Resumee:
Charging pack up to 4.2V/cell
Discharging down to 3,3V/cell
Using 40Ah
1h-1,25h foiling fun, Battery doesnt get over 40Degree Celsius

Going below 3,3V/cell doesnt make sense, voltage starts dropping fast, and to maintain 1800W you need for example at 3V/cell already 50A. At min Voltage of 2,5V it would be already 60A
Half full - Full i only need 35-40A, wich i think is a good value.
In theory i could get 8 more min, if i would go down to 2,5V/cell, but why should i?
I hope, my packs will last for a long time this way

1 Like
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That is very nice , thank you for the numbers , I use 12s8p of 30q and I can not get more then 17A of my pack before voltage sag or over heat if I set the battery amp max above 70A

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I think the double bearing is important, it takes the axial load and distributes it to the double bearings.

1 Like
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Wind issues
Ok, now i know, why we need so much power. Its a matter of angle of attack of forces.

If i go downwind, i can easily foil with 30A, against the wind i need at least 40A.

With just “a little bit” wind in the back, i need much less Power to maintain foiling.

Maybe a Backpack Motor like paraglider have is the solution :thinking:

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Then why bother with a motor underwater at all?

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Or cheaper, lighter and easier to pack we could see our motors as electrical assistances for foil wings to facilitate take-offs and/or waterstarts which are today the 2 pains of the activity… motors positioned mid mast to avoid folding propellers (1). We know ebikes, we could have ewingfoils for those 8 to 20 knots of wind days…:wink:
@ELEVATE.rocks, a market for you and your autonomous pod (to be presented here in a few days ?). The idea being that it is swiched-off and out of water most of the time.
(1) Water touch downs won’t be an issue without folding prop if a water detector switches the motor on automatically when detecting water
ewingfoil_2

2 Likes
58

What about 2x grunty EDF on the Wing… :rocket:

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Has anyone ever tried to tilt the Motorunit? Any results?

I think about tilting the motor down, and giving the backwing less downforce/more lift

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I don’t think it would be worth tilting the motor unit. Its most likely just going to make it harder to ride.
Even changing the length of the motor pod changes how the board rides.

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It’s going to be pretty hard hold a remote and foil wing, and then use your arms to stand up. The complexity of the wing starts comes from wanting to start standing up, but wanting a board as small as possible (i.e. the board will have a low buoyancy). No form of assistance can really help with this.
An automatic detector will come with a bunch of other complications, like how much power does it need, this won’t be constant. What happens if the touchdown is simply a loss of balance and then the motor kicks in and makes it even worse.

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weight and power needed

When i ride alone 72kg + 23kg board i need about 1800W
Together with my son (additional 22 kg) i need at least 2600W for foiling

So 23% more weight --> 45% more Power needed :astonished:

2 Likes
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What is your wing ?
We found that 1200cm wing is really hard when rider is 90kg+ It needs a lot more speed

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Its René’s RL efoil optimized foil

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Do you have a log to know the foiling speed needed for 2 ?
Also do you compensate by titling the nose up?

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No logs for speed yet, sorry. But you are right. Together we need more speed to get and stay on Foil

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Thats very interesting! It makes though as I weigh ±90kg and find that I use around 2500W to foil at a comfortable speed.

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I actually thought the same to try to keep the board more leveled while planning… but then when you’re flying, it would add extra drag (more frontal area).
As you spend more time flying than planning, it’s better to optimize the first …
You can play with the backwing to get your board leveled in flight though…

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I tried to shim the backwing, first 2mm, then 4mm down at the backend, without any noticable changes in flying behaviour!?

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That’s strange, that’s how all manufacturers advise to change the behavior of a foil…
especially that your back wing is pretty big…

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Yeah, strange. Not what i expected.
Maybe i have to shim more, or even have to turn the Backwing upsidedown. The top surface is quite flat, the side faceing downwards is more Like Aerodynamik Airplane profile.
Maybe even a shim with 4mm wasnt enough to lower the downforce of the backwing?