Alien 200A 3-16S vs Seaking V3 130A vs Flier 400A


8awg is good for 73A current continuous within safe operating range for wiring.
10awg is 55A, but 400A unit runs dual 10awg meaning 110A.

You’ll notice I mentioned 8awg or dual 10awg wiring in the ESC post above :slight_smile:



Make sure that the ESC is programmable so you can limit start up speed of the motor. Look for heli or plane-mode and play around with slow, medium and high. The gearbox is the weakest link and telling the ESC to hold back on the torque is mandatory for its health.

On thing that I found regarding ESC and heat is that some ESC’s are made to run at full throttle. If you run it at 50% you will have problems with heat building up. One way around this is to configure “freewheeling” in the esc. Watch this for more info:


This is very interesting and clear, but how you know if your esc should need that? If so, is there any way do “freewheel” the esc from the outside?


Hi! I guess it all depends on the ESC. Look trough the manual. Sometime they use another term for it.

If this is correct we should strive to keep the A as low as possible on the esc. A high A esc will only generate more heat when not running on full throttle.

Given what we know we should be able to use a 80-90A esc. That’s in theory anyways.


Every ESC is most inefficient at 50% throttle. So producing more heat.

Not quite short explanation, but a good one.
(for the lazy ones, it is about at 20mins)


I’ve played with my Flier 200 16s software but I can’t tell which of the setting should be the freewheeling one… Got that for cable size and the hi current limit (it’s the watercooled) but now seems not that good idea…


Sorry, this theory is definitely wrong in every aspect.


Why in every aspect? The fets have a certain Rdson, cables and stuff have certain resistance to and PCBs have an amp limit. So all this resistance will produce heat with P=I^2*R. So keeping the Amps low will solve many problems.


Hi PowerGlider, please elaborate.


What is your plan, maybe i did not get it?


The motor and battery current is in most cases not controlled directly by the ESC, except the VESC and some EV controllers. So the current (at full throttle) is dependent on the battery voltage and the load of the motor and its Kv. So using a smaller ESC with less Ampere rating will only lead to a burnt ESC. Maybe it will protect itself from Overtemperature in some way, but all the burnt ESC in the RC-world and also here, show this protection is insufficient.
To reduce the motor current you can do mainly these things:

  1. Choose a prop with less pitch and/or diameter
  2. Reduce the voltage of batteries
  3. Choose a motor with less Kv
  4. Choose a higher reduction gear
  5. Reduce the applied throttle signal (Dual rate it was called in former times, you can do this in your transmitter by the settings, e.g the enertion controller allows to half the max throttle, called beginners mode)
  6. Choose a ESC which has shunts or other measurement for the motor phase current to limit it.

Every solution has its pro and cons, and most times a combination will give the best results. E.g. if you go for 6. you might additionally choose one of the others to reduce overall motor current to increase the overall efficiency.

I have done so after burning a too small motor with a well cooled YEP120A HV watercooled ESC, which failed itself when the watercooling was not working anymore. Afterwards i chose a larger motor (6374 -> 6384) which burnt my VESC because i increased the temperature limit settings without having a proper cooling.
So next step is a better cooling for VESC in combination with a smaller prop (175mm -> 140mm) and a motor with less Kv (6384 130Kv -> 6384PG 100Kv). Direct drive outrunner with direct water cooling

So the misunderstanding here is that the ESC will limit the motor phase and/or battery current. The currents specified are a rating what the ESC can withstand without damage, often limited in time and always presumed you have a very good cooling.
So typically you end up with overdimensioned ESC, motor, batteries and cables to get the performance you want, burning some of the components from time to time, especially when the conditions change. This is intended by the RC industry, so they can earn more money. It could be solved easily with a phase current limitation which is matched to the motor and battery capabilities. The VESC provides all these features, but has the drawback that the original cooling is very bad. There are better cooled and designed VESC available, but the cost to performance ratio goes through the ceiling. You can try yourself to improve the cooling by water or air.


Hi PowerGlider!

Thank you very much for clarifying. I’v only worked with “real” controllers, Sevcon, before so I took for granted that the ESC had a shunt that would limit amps.

Choosing the right components and dimensioning them all to match the ESC is key. Cooling is another crucial point. Im going to perform some surgery to my YEP120A to make sure that the FET’s are cooled in a proper manner. Heatsink AND water cooling would be ideal.

My guess is that the temp rises FAST when water is blocked and the ESC could burn in a few seconds depending on the load at the time.

In building a version of the Hiorth brothers foil so I know my amps, 70A at peak and 50-40 at cruise.

Thanks again



There is a problem with the YEP120HV WC: The cooling pipes have connection to the battery. If you have a “open” cooling circuit you make a good contact to water and if you have a single isolation failure somewhere else it hurts you, might risk your life.
So i decided for myself not to have any watercooling or anything else which connects from inside the battery/ESC housing to outside. I also want to eliminate the kill switch, because it can kill you. So there is only one connection out from this housing and thats the motor leads, IP68 protected. If there happens a single failure in the isolation there, it is easy to detect in salt water and you have to go home, make it better. I would also recommend not to use switches which have a metal housing, because if you have water ingress into the box, it might create a short between the switch housing and battery. So in the moment you touch the switch you get shocked.


I was not overly concerned with electric shocks for myself until now. Your hints are still good advise for developing the electronics. Am i missing something if I assume 12S voltages are always safe (<60V DC, in wet environment)? In Germany there are the rules for extra low voltage(„Kleinspannung“). I have had some encounters with ac and dc at 50V and you can feel it, but not really much.
:hotsprings:️However, I consider boiling water and/or molten metal shooting away from shorts as a higher danger, after seeing it with wrong settings while spot welding.
Thanks again for keeping some security advise alive, that is always appreciated.


A car battery with 12v can together with the coil and breakers produce sparks of 10 000 volts or more for the sparkplugs. The esc can produce voltage spikes that kan kill the esc itself (if you do not have enough capacitors) so it is not impossible for it to be harmful, if it is likely that is another story.


Please have a look at the new thread opened:


The electricity is and has been my main concern from battery chemical fires, to hot wires to ESC’s shorting out, to getting shocked. I touched on this is a post a couple months ago and PowerGlider has shared some great info above in the link confirming this.

On a lighter note getting shocked with AC from the motor is better than DC… DC forces your body to lockup until you die or disconnect, while AC provides the pulsing allowing us to react and let go. The good news is that if you get shocked while riding… it won’t be long before you fall and disconnect :slight_smile:



Ok, do you know if it’s a direct connection between - and the pipes? My guess is that that would be the same for the esc:s using heat sink and wc as well? Fet:s are normally connected screwed to the heat sink in which the pipes run.




The cooling pipes are grounded (there’s a link through the PCB to the negative terminal).


At last it worked!!! I powered the Flier 200A 16s (same as the Alien) and it works, cool. But, just save me quit cursing, it’s impossible to set just by the beeping and remote, definitely an absurd method. So, all pumped up by the sound of the SSS360 revving I got the Pl2303 usb to uart, disconnected everyrhing and… The usb don’t work!!! Seems a driver issue but I tried everything, any driver from 2007 to now. Nothing. Error 10 message, no way to plug ESC to computer. I ordered a different adapter… Let see next week. No answer till now from Flier