Need Suggestions: Building HV buggy

[tom255]

I have Kyosho MP777 buggy, its laying somewhere under bed. I dont want to run nitro much so thought maybe to try out HV conversion.

I want to go budget and dont want waiste money too much.
First plan to use: Sentilon/OEMRC/Turnigy 100A 12S ESC (go around delay to set motor to spin a litle bit on neitral position using "Tekno" clutch)
Use mech. brakes

And now need suggestion about motor. I dont want to spend a lot of money on that and advantage of HV is low current=low heat.
What you think is it worth to buy low KV cheapo feigao type motor? like 15XL
or maybe something smaller L cans? or maybe some other cheap alternative?
Second suggestion need about battery: I have 2x2500 4S batteries.
Maybe to serialize them and get 8S or buy additionaly 2500 and put it also serial to archive full 12S advantage? Is it worth go over 8S?
Third question about UBEC, is it availible somewhere that can handle 12S lipo or hook usual bec to balance tab of one battery?
Sorry for my English i hope you understand me
Thanks

[Sammus]

You may need a custom motor mount as well, since the tekno clutch will make the gear sit a lot further forward than a normal mount.

[tom255]

Motor mount not problem, I have CNC router and smaller milling machine.
Building is most interested part for me its not problem. But I dont have any experince with HV systems (over 6S) and want to try out.
Can I actualy run lets say feigao 15XL on 8S continuesly without any fan until battery dump if to gear it lets say about 45mph
And how much runtime i can expect from 8S 2500mAh battery

[Sammus]

15XL on 8s would sit between 30000rpm and 35000rpm which I think is pretty good. I dont have a lot of experience though, just a lot of reading :)

[_paralyzed_]

I really don't think letting the motor spin a little is a good idea, IMO it would cause a lot of heat, these systems are made to move, besides probably blowing up the esc, you would have constant clutch problems. The only problem I've heard of the start delay is correcting jumps mid-air, and the programmer has a soft start off selection, maybe those with problems didn't have a programmer?

[Sammus]

I have the programmer and can verify that with the soft start off its still very soft. Correcting jumps mid air and controlling drifts are the two biggest problems. Me and my brother are both eternally frustrated by the problem. I'm by no means a n00b when it comes to RC driving, and he is the most experience and talented rc driver and tuner ive ever met. I guess anyone can say that, but neither of us never want to use that damned thing again, and i hope someone can trust me enough to be saved the hassle as well :) If all you want to do is high speed drag racings its fine. there is no chance you could race competitively with it.

[tom255]

Idea was let motor spin a litle bit, it mean that clutch not engage, like Idle on Nitro motors. I noticed that if motor spins about 10s with this ESC and you hit full throttle it spins up instatnly

And if speak about ESC even if program soft start setting to HARD it still spin up slowly, no chance to drift or correct trajectory in air

[brushlessboy16]

did u think of actually at nuetral(sp) throttle to actually have the motor spinning at a decent rpm? maybe 2-3000rpm.. there goes all of you problems :D

[Sammus]

Yes that is the idea brushlessboy. Will be interesting to see how it goes.

[Sammus]

Originally Posted by tom255

Idea was let motor spin a litle bit, it mean that clutch not engage, like Idle on Nitro motors. I noticed that if motor spins about 10s with this ESC and you hit full throttle it spins up instatnly

And if speak about ESC even if program soft start setting to HARD it still spin up slowly, no chance to drift or correct trajectory in air

Yes this is right. The only options (See on the card) are "very soft", "soft" and "normal". Even on normal there is an extremely noticeable and frustrating delay. If you keep the motor spinning inside the clutch it may help, thought I think this isnt good for the ESC because of how they limit the rpm.

[tom255]

Originally Posted by brushlessboy16

did u think of actually at nuetral(sp) throttle to actually have the motor spinning at a decent rpm? maybe 2-3000rpm.. there goes all of you problems :D

I did not understood your question actualy.
Yes i think that problem with delay dissapear!

Anybody can confirm this too that ESC dont have delay if you let spin motor on slower RPM for a while? My esc actualy do that but i have 6S version maybe 12S is different?

[Sammus]

I think it has to do with the throttle position in the ESC. This is how it works:

If you are driving slow at low RPM then give full throttle, the car accelerates with no delay.
If you are driving fast then release the throttle slightly, then give full throttle, there is a very noticeable delay. This leads me to think that the clutch idea may not fix the problem. If you want to try it I have a Turnigy HV ESC I want to sell. PM me for details.

[tom255]

Sammus
Do you slow down releasing trigger to midle position or just slowind down not going to 0 position with trigger. I will check later on my esc that...
Maybe ESC detects that it triggeri is in 0 position and try to spinn up with delay again?

[Sammus]

I always release to 0 position, but accelerate with the motor still turning. Maybe just releasing part way could help. I will have to try it when I get home on monday.

[aqwut]

Originally Posted by Sammus

I always release to 0 position, but accelerate with the motor still turning. Maybe just releasing part way could help. I will have to try it when I get home on monday.

Have you set the throttle range for the Sentilon 12S100A?
I set the throttle trim to about 40% forward..(just enough not to spin the motor) and I don't have that delay problem.. I don't know why so many people are having this problem..