Newbie Planned Build

EFOIL.builders Builds
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Hi everyone, I just joined and have spent some time reading through the pages. I am glad I found this group because there is a lot of good info here. I had the build pretty much spec’ed out in my head, but I figured i’d post here. I am coming from an esk8 building background for the past couple years. My buddy is also going to help me out who is a surfer and has a couple foils.

Basically I am planning something like the Lacroix vortex as the prototype to test electronics and battery etc. then eventually build a full board from scratch.

Battery
I am currently building a 12s6P molicel p42A pack for an esk8 and am hoping to double dip and use this for the efoil test battery. If everything works out well, Ill build a bigger pack for the efoil. I could do 12s8p, 10P or even 12p.

Will 12S6P work for testing? Is there any way to estimate run time? Obviously that depends on a million factors. But would 12s6p be consider medium sized with 12s12P being on the larger end? I cant imagine anything anything below 12s6p having any significant amount of runtime.

Electronics
I plan on using the Reacher 65162 120 KV Brushless motors and their 300A speed controller. They have a program tool for the esc that I have been reading up on. I am more familiar with VESC and using VESCTool, so that will be new to me. I plan on pairing the VX3 remote or simlar maytech remote with the esc. I will put an antenna on the top of the board so signal is not obstructed. I will conformal coat electronics and make moisture consideration when placing the esc. both from water and condensation.

I’ll mount the motor at the bottom of the mast obviously and the esc and batter at the top of the mast. Wiring will be routed inside the mast. It sounds like its a good idea to use corrosionx on motors in general. I am not too familiar with that, but will look further into it.

Do people generally use hall sensors ? or sensorless?
What is the best way to do a power switch? some type of waterproof antispark switch? Waterproof loopkey?

Foil Components
Right now, I am letting my buddy supply the board and foil. in the future, I will model and print up my own. I am fairly skilled in design and printing. I have also experimented with carbon fiber wrapping these components. We will mess around with board size, mast height, wing size etc.

What propellers are people using? I assume the pitch and size matter for speed acceleration and kv and voltage of the system… but is there a common place to start?

And i guess my overall goal is to create a DIY that is good for cruising around fresh or salt water, hauling me (230 lbs) up to 20ish miles an hour for 30-60 minutes… more would be better, but i am new to all this, so I do not know if my specs are even close to achieving this?

Are there any other areas that I should concentrate research on?

Thanks

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Too many questions for this late hour for me but you can calculate roughly 1-2kW consumption during riding.

Your goals are then totally reasonable. With 12s x 3.6 x 4Ah x 6p wh, roughly 1kwh you’d get between 30-60 minutes depending on conditions and your ride style. Scale this with the number of parallells if you want longer range.

1 Like
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A 12S6P battery pack using Molicel P42A cells should work well for testing your efoil. It’s a decently sized pack, and while it may not provide the longest runtime, it should offer a good balance between capacity and weight.

Estimating the runtime of a battery pack can indeed be challenging, as it depends on various factors such as the efficiency of the motors, the weight of the rider, the terrain, and the speed at which you ride. However, you can make a rough estimation based on the capacity of your battery pack.

The Molicel P42A has a nominal capacity of around 4200mAh per cell, so a 12S6P pack would have a total capacity of approximately 75,600mAh (4.2Ah * 6 cells in parallel * 12 cells in series). To estimate the runtime, you would need to know the average current draw of your system during operation.

For example, if your system draws an average current of 10A, you can divide the total capacity by the average current to get an estimate of the runtime. In this case, it would be roughly 7.5 hours (75.6Ah / 10A = 7.56 hours). Keep in mind that this is a rough estimate and the actual runtime may vary.

Regarding the comparison of pack sizes, a 12S6P pack would be considered medium-sized, while a 12S12P pack would indeed be on the larger end. Smaller pack configurations, such as 12S4P or 12S3P, would have less capacity and therefore shorter runtimes.

Ultimately, it’s important to consider your specific requirements, such as desired range and weight, when choosing the pack size for your efoil. If you anticipate needing a longer runtime or higher capacity, you could consider building a larger pack, such as a 12S8P or 12S12P, depending on the available space and weight constraints of your efoil.

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This isn’t correct, for packs capacity you only count capacity in parallel. That would be 6x 4200mAh= 25200mAh or 25.2Ah. If you want to calculate packs kWh, then you add series and nominal voltage (3.6v)
12(series) x 6(parallel) x 4.2Ah(cells capacity) x 3.6v(nominal voltage) = 1.088kWh

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Just calculate in Wh: for LiIon:
Nominal Voltage x Nominal capacitity in Ah x #cells
3.6V x 4Ah x 72= 1036.8 Wh for a 12S6P pack witch Molicel P42A.
Then assume 85% usable capacity to calulate how long or how far you get. An efficient efoil can run 25km/h@60Wh/km.
As a reference. I can pull 1200Wh out of my 12S8P pack from P42A, nominal capacity is 1382Wh → 86%, it was a bit more, when the pack was new. If I run @60Wh/km, I can get 18km @25km/h average speed (not 20, as takeoffs need more energy). 18/25x60 = 43min run time. If you are a beginner, you spend more time and do less km…

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Thanks everyone for the comments so far. reading through each one has given me a pretty good feel for what to expect.

Also I figured id drop the motor and esc I planned on using here. I haven seen anyone else on the site using this. In the esk8 world, Flipsky is considered meh, while Reacher is considered to be a bit higher end. has anyone heard of this before?

I do currently have a Flipsky vesc in one of my DIY esk8s. I haven’t had any problems, but I run it pretty conservatively. I should elaborate that people do seem to like flipsky motors, its just the vesc that they do not like. Generally the remotes are ok too. people seem to like the vx4 a lot. I have one of these too and have not had issues yet either.

I am not sure that this esc is vesc based, so it would not be tuned in vesctool which I am familiar with. After talking with Reacher, there is a standalone tool that connects to the esc to adjust it. I got the pdf documentation for it and it seems like it wouldn’t be too hard to figure out.