E - Windfoil (Netherlands)

EFOIL.builders Builds
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Hi Guys,

I have been reading and learning so much from this forum, time for me to make a contribution.

I started my project mid 2019 having stumbled upon this forum. I have been windfoiling since 2018 and been having a blast doing it. We live next to a small lake surrounded by trees and the wind is always gusty and less then the surrounding area. Using the windfoil already increased my time on the water, but was still looking to have something for those windless days. So the idea was to use the existing windfoil gear to start e-foiling.

The first iteration hit the water in september 2019 and was completed for less than $1000. I was using a Max 004 case with two 12 Ah 6S Lipos. For a foil I was using a Neil Pryde ALU first generation, ESC: ARC200, Motor: modified APS 80100, RC: $30 waterproof remote
I did manage to get foiling on my knees on this setup, but the foil was very unstable, the battery case leaked, the prop broke after a couple of sessions and the batteries only lasted 10-15 minutes.
But concept proofen…

So time to move on to better gear. Over the winter I bought a new foil, better battery case and built my own battery packs. My idea was still to use my existing windfoil boards and therefore looked to a system which could be retro-fitted. So I stuck to use a suitcase type battery box. I chose a Nanuk910 case as the basis, because it is relatively low profile, and it has .stp files available allowing most of the prototyping to be done in Fusion360.
I managed to squeeze in all the required functions in the case:

As a foil I am using the Slingshot Hoverglide Infinity 76 which I am really happy with. Also for windfoiling this foil gives early lift and is really stable.
For now I am using some 3d-printed covers to guide the cables up the mast and duck-tape to fit everything in place. I am planning to buy a separate mast so I can leave the motor and cabling in place when switching from e-foil to windfoiling.

The board is a RRD H-Fire 91. It is 145 liters and measures 236 x 91 cm. The setup has also been tested and working well on an old Starboard Start measuring 230 liters at 18 kgs.

IMG_20200424_164448 (1)
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I have also tested the setup as a boost motor for windfoiling, however this needs more work. The 80100 motor gives a lot of drag, and having to trim the sail and operating the throttle at the same time is kind of overcomplicating things. Maybe with a folding prop, a thinner motor and some kind of throttle mechanism on the boom it could work.

ewindfoil
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So I have been riding several succesfull sessions on this setup now. It has been a really fun experience getting to this stage and riding. Along the way I learned 3D printing, 3D drawing in Fusion 360, spotwelding and battery design etc.

A big thank you to the forum!

Shoresup

12 Likes
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Nice case , any pics of battery terminals ? Thank you

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This is the finished case. Happy to share designs if interested.

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How long are you able to foil with that size battery? Would love to see a copy of your plans.

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This is awesome! I love the one case design. Thank you for reporting success with that foil; I have the 84 available for testing and will give it a go when the time comes. One thing I noticed was your 200A resettable marine breaker. On full charge your battery is ~50V at maximum. The breaker is only rated up to 48V meaning there is a small window (from full charge until 2V have been discharged) where if a short were to occur the breaker would go but the circuit could remain closed due to flashover. I am using this fuse rated up to 56V for 200A however I do not have reset functionality which stinks.

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It is the EL-AN200 on Amazon for $20. Also, do you monitor the temperature in that case? I would. It looks clean but there is risk in packaging a heat producing ESC and battery pack together and I’m not sure water cooling makes it any safer. I am only critical of these design choices because when something fails it’s going to damage a bunch of stuff with it. The build looks beautiful otherwise and I bet it is really fun to ride.

Best,
Peter

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Hello,

At the moment the batteries allow for about an hour of play. Minimum power to foil is about 2.5 kW. But still optimising. A lot of stop-and-go still. I am using this prop from Volker Volker’s Build - 80100 18650-30Q - #143 by V_S - Builds - FOIL.zone, but have some issues with cavitation at high rpms. I have printed it in PLA and covered it with a layer of carbon, maybe it is just not pure/accurate enough. Currently experimenting with the https://www.wageningen-b-series-propeller.com/ tool, to design my own propellor.

Below are the designs for the center console in the case and the battery spacers for the 18650.

2 Likes
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Hello calikiter,

I see your point. It is indeed rated at 48V. However also marked ‘anti ignition’, which is probably the same as ‘anti spark’. I am using it mainly as on/off switch and ‘anti/spark’. Under load the voltage quickly drops to around 48V anyway, so don’t think it is a big problem.

The ARC200 measures it’s own temperature, and throttles back if it comes closes to a threshold you set (80 deg C). I first attempted to cool the esc with a CPU cooler, but as everything is so closely packed together, the hot air cannot escape. That did not work. The ESC quickly got up to it’s max temperature and then throttles back.
So moved on to passive water-cooling as many have done on this forum. Luckily I had already fitted a water cooling block in the design. In the picture below you see the bottom of the ESC with the water cooling block and CPU cooler. With the water cooling, the ESC termperature goes up to about 50-60 deg C, so well below it’s limit. Also the batteries seem to be up to their job, just luke-warm after a session.

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For spark suppression I use an XT-90 anti-spark loop key. Not a good idea but will have to be upgraded in version 2. I unfortunately have several XT-90/10awg wire “fuses” in my circuit. I will need to cut the leads on the Li-Po packs and change everything to XT150 and 8awg in version 2. It is kind of misleading that these Li-Po packs use XT-90 connectors if they can supply more than the connector is rated for in my opinion.

The temperature based throttling feature is slick! I have never heard of the ARC200. It is unlikely the temperature sensor will fail and if the CPU is damaged breaking the throttling functionality it’s not like the board is going to still be riding!

I will be looking into water cooling in my version 2. For this version I’m using thermal epoxy, an aluminum enclosure and a huge aluminum heat sink. Time will tell how this goes (also my build thread).

1 Like
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unfortunately the ARC200 is discontinued:

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Bummer. I’m not sure how the guys working on the VESC firmware would react to a closed loop temperature sensor circuit addition. I do believe this could be accomplished by polling over UART to get the temperature then using the same data channel to update current limit settings on VESC.