I don’t comment here anymore, but just once again just for the insults to build character.
I think the problem that is part of this thread of comments relates to cruising speed. More than the amount of power used. You can’t change the laws of physics and cruise at the same speed using less power by changing power settings.
FD users report slower top speed with the 3 blade prop, as expected. So matching speed and prop pitch will change power required but at a cost. Other posts and comments on this are on the site.
Although the common view here is that Foil Drive limit battery amps to limit top speed, yet somehow still allow more battery amps for getting on foil is an argument I’m not going to engage in.
So I will just state what I did, and if the usual people want to insult me, they can just fuck off.
I used ERPM limit to replicate what my FD Assist Plus did. I set motor amp max to what I need to get on foil, 80 amp. This sets the throttle range. You can also select other parameters for throttle range in VESC tool, others can comment if they have done this.
With an ERPM limit, mine is 23k with 14s, this gives me around 22 km/h top speed which is what I need to push against the wind and swell in the shitty conditions I foil in. The motor amps are around 40 amp from memory at this speed, or for what I think is the issue here, 40/80 or around 50 % of max.
My opinion, is FD do this too. The HP max is around 80 amp max, boost is just over 100 amp for a short time, top speed around 15 km/h with my guess ERPM limiting resulting in around 30 amp to the motor.
Thanks. Yeah i use the balance wires and get my charger to balance the packs.
Actually… on this topic… is it worth adding a BMS? And if so can anyone recommend a make/model for 6S2P pack of Molicel P42A 21700 cells? I have read of people having issues with aliExpress BMSs.
Thanks for this.
Funny… when i asked ChatGPT about percentage throttle and efficiency it replied stating why on earth would i consider throttle percentage when the real question relates to current draw, RPM, prop pitch and size, etc.
So once I replace my ESC with the VESC it sounds like I need to do a deep dive into VESCs (of which i know very little).
Thanks again, i will read about these settings.
Thanks guys.
Actually after fixing the initial problem (motor phase wire solder joint) the system works flawlessly. So i am a little hesitent to replace the little 80A ESC.
Ive just ordered a HOTA D6 Pro charger which can charge 2 6S packs in 1/2 hour or so… so i am committing to 2x 6S packs. I’m just not sure if I should add BMSs to my new packs
A friends 13 year old son had a crack and got up after a few attempts. And had few others interested so suspect i will build more.
@ZedMan oh you are faily close… i am on the Sunny Coast (Bokarina). I would love to take it up to DI once i can ride waves (yet to try the surf).
Tim you don’t need BMS if you are charging with the style of charger you are using. Had good success with the Daly BMS if you want to use a simpler charger.
It works really well, however the Molicel P42A cells I am using are not up to the task as I am running 12S2P (2 x 6S2P packs in series). The cells get very very hot and voltage sag is evident after about 6 minutes motoring resulting in having to stop around 10minutes. To be fair I am new to foiling and end up using a lot of power a lot of the time… rather than what this system is designed for (assist only). Ie I am not doing a lot of foiling/surfing. Also worth mentioning is that i am likely killing the batteries as i am riding an Axis ARTv2 999 foil… which requires a lot of speed. So i will try another session on a slower and bigger wing. I should probably rebuild using 3P but I find the 2P setup manageable weight-wise and think more might be uncomfortable.
So I will order some RS50 cells and use those. And will repurpose the P42A cells for a 12S4P setup (I will post details - will be an on or in board setup).
Also I have ditched the original aluminium Flipsky 2-blade folding prop as it is too noisy and I have been using a 3D printed 3-blade prop. This works incredibly well - it is much quieter and has more torque and less battery use.
I got the model from here: Propeller for E-foil / ASSIST - Share Project - PCBWay big thanks to @Bzhwindtalker !!
I printed the hub with an FDM printer (Bambulabs P1S) using PETG-CF (6 layers and 50% infill).
And the most amazing discovery is the Siraya Tech Blu resins - I have used the Black Lava - this is incredible - it has a very high tensile strength and tensile modulus - I am sure on par with the Formlabs printers/resins that the FD team use. So I have printed the props in this resin on my very old AnyCubic Photon printer. I haven’t even sanded them - just washed in IPA (5 mins), dried with a paper towel and post cured for 15 mins (in an Elegoo Cure station).
I have printed spares… but not needed them (to be fair I have only used it 3 times).
My original BDUAV 6384 motor died… I had mistakenly crushed the wires coming off the coils against the housing when reassembling and this caused rapid oxidation and the wires broke too short to salvage.
So I have replaced it with a new waterproof Saite 6484 motor… this, it turns out is much better. I can cruise on my high aspect foil (Axis ART v2 999) at 50-55% throttle - where as previously I was cruising around 60-65+% which was causing my batteries to get very hot.
Now I find the batteries only get warm (quite warm) and I don’t experience the dramatic voltage sag I was getting (well, not nearly as badly).
So it was a very positive change (although at 4 times the price you would probably expect that).
hi Thuffam: Really interesting your achievement. I am new in this area. I would to know how you join the cable and the leash together. Can you post a detailed picture? Thanks in advance.
Hi. Nothing special here… just used some 25mm webbing. That is tied to the waist belt and attached to the legrope attachment point on the board. These are held together with loose mesh cable tidy thing like these: Keji Mesh Cord Concealer 2m Black | Officeworks
i have snapped a few props. No a prob as a quick change on the beach and i have printed loads of spares. I initially though i had hit something but turns out it was whebln i hit the throttle too hard when coming off foil. As im currently using a ESC so no chance to do a slower rampup. But now i am aware of this i simply dont slam the throttle and i havent broken a prop since. It was interesting to see the props all broke at the base but not staight on the layer lines which confirms what ive read that UV printers layer strength is far superior to FDM printers. I print the blades vertically so no post finishing required (it produces near smooth finish right of the machine).
Now ive got much better at foiling my run time is greatly extended. My last session (on my 12S2P pack) was 30 minutes! Super stoked.
I have done sla blades as well using magforms rigid 100. Super stiff and prints beautifully vertically as you did. Not much time on them yet to say they are bomber but time will tell.
The ones I did FDM print, all broke at the base.
And I had them setup almost horizontaly, so it was almost 90° to layers.
Only ones that did not break were PA12, but those were too soft.
Mine always broke when something unusual happened, like when a wave pushed me backwards or something like that.
So I gave up eventually. Guess there is a reason most commercial vendors have completely switched to alu. For me the ratio between money saved and hassle switching props really did not work out.
