Hi all,
I recently completed my own DIY foil asssist on 8s.
I’m using 8s3p with molicel P42, 100amps flame esc and 6384 motor 120kv.
After a few minutes riding my 43litres custom, motor fully stopped and a nice smoke started coming from it…
For those who have successfully built a DIY solution of assist in 8s. How do you handle load? Have you had any issues with your 6384 motors?
Cheers,
Jordi
Did you have any cooling on the ESC? I assume thats what overheated and burnt out.
I run a 70A vesc and have notice that it goes into temp shutdown after about 15seconds. I’m going to need a much bigger heatsink!
I run 8s3p with a hobbywing ezrun max6. This has been working well for me. It has a built in fan but I don’t have a heat sink. I only use it in short bursts though for getting on the waves.
When it happen on the water that’s what I thought but after analyzing the components, battery and ESC are still good.
Esc has an aluminium heatsink going over the case to the outside and still works perfectly, battery dropped to 32 ish volts. Worst part is the motor (totally fried) and the cable going to the motor which got melted in some points.
6384 is able to take 80 amps according to spec but I’m surprised even under water it had not enough cooling.
Apparently, by sizing the prop you can limit the max amps drawn but wondering if there’s an easier way.
Thanks,
Jordi
The propeller decides the load on motor, can’t change that fact. Size the propeller so that you reach at least 50-60% of max rpm during full throttle, then you’ll have an OK efficiency with your motor.
Apart from that it’s advisable (if there are problems like motor burning) to use an esc with programming and logging, like a VESC. This gives you information and control over the motor drive. A simpler esc is hit and miss, it might work, it might not but you won’t know why.
A tip on the 6384 is to separate the phase wires that enters the motor, they are normally bundled together there which creates a hotspot that can burn through the insulation (water doesn’t reach to cool in this spot due to the bundle)
Agree Vesc would be best to limit the amps but there are not many options for one which will fit onto the box and is reliable enough.
Already tried the Flipsky min 70amps and it’s rubbish.
Any other options you’d recommend?
Thanks
APD120f3 or APD200f3 are small and specs are great. This is what i will try for my next build but i haven’t used one yet.
Exactly where di the motor smoke? Close to the motor underwater or wires above the water?
Difficult to tell to be honest.
I was pushing to get up on the foil and all of the sudden motor stopped/locked. Tipped the board upside/down and motor was smoking.
Looks like esc kept sending current so cables melted at two main points, were bundle enters motor and at esc/cable connection.
I’m using a high quality flex cable with 2.5mm section, same supplier as foildrive uses.
Jordi
Got a link to the cable?
Cable;ÖLFLEX® CLASSIC 400 P;3G2,5mm2;sin
blindaje;300V,500V
Fabricante: LAPP; Símbolo del fabricante: 1312403; Conforme con
RoHS
Purchased to a TME electronics, a spanish company.
Interesting…
I used a 3 core 2.5mm2 silicone cable which is really nice and bendy and comes in black. I have noticed that it heats up pretty quickly though when I have full throttle.
Isn’t this ölflex 400P rated at something like 30A? It’s a PUR/PVC insulated cable so it won’t conduct heat.
For my 6s built I used succesfully a 3x2.5 generic cable. I wanted to upgrade from this so I went for a well branded cable as FD does, not sure what the rating is.
That’s crazy, do they have a limiter on their kits so that it only gives drive for 5 seconds or what? Otherwise they’d get to replace some burnt kits on warranty.
Seems to be rated for constant current of 30A. I guess if not on the throttle constantly it may be alright…
I actually think of of the best ways to do the foil assist is to use separate 12AWG cables and sheath them so that they can vent heat easily.
I currently run this: 2/3/4-Core Silicone Rubber Cable Tinned Copper Wire Soft Power Cable 0.3mm²~4mm² | eBay
In 2.5mm2 and I can tell you its toasty in 30 seconds…
12AWG = 3.31mm2
You could also get a 3x4mm2 or 3x6mm2 cable here…
@Larsb and all, thinking still to try to use the current controller with no limit option…
Assuming the 6s setup reaches the 6384 required rpm and I know does not burn, as I’ve been using it for a while.
could I match the pitch of the prop for the new 8s setup? Would this be a conservative approach to have same top speed and more acceleration?
RPM x pitch = advance (assuming no slip)
Making equal advance speed on both setups I get:
What do you guys think? Am I missing something?
If you go down in pitch and up in rpm you’ll give the motor an easier time, motor amps will decrease from this.
But if your ESC doesn’t actually limit current and the current was voltage limited at 6s then the 8s could actually give higher phase current during starts if you max the throttle. It could be the case but i think it’s not so likely (but we don’t know the algorithm in the ESC).
