Need Suggestions: Building HV buggy
 

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

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.

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

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 :)

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?

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.

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

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

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

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.

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?

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.

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?

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.. :intello::neutral:

I don't have a delay problem either.

I run a feigao 14xl on 8s lipo. It is in a savage, which is heavier than your buggy. The motor gets up to about 160f after a 25 min run. I use a pair of 4s 3600 lipos. They are 12c rated, so can put out about 45amps continuous. The lipos do warm up, but do not get hot, maybe 110 at the most.

This setup makes alot of power, more than a 8xl on 4s and maybe a little more than a 7xl on 4s. It runs much cooler too. I would recommend this setup, especially in a lighter vehicle. I think your 2500 batteries will be fine, even geared for 45mph.

I am using a great planes 60amps hv air esc. It has a bit of a soft start, but I can drive around it. It makes for a few wheelies, but not too bad. I have the turnigy hv esc that is going in my yusa rally, that car has a tekno clutch, so I will see how it performs. I will not have that car ready for a few weeks though.

I still say letting the motor spin all the time is bad. I can't explain why, it just feels like bad juju to me. I would trust aqwut's reccomendation on setting throttle trim to dial out the soft start, he's got a hobby shop worth of high end brushless setups, and more real world experience than most. Plus, he's from Canadia, Cananadans know their stuff.

But I dont understand what bad in that then motor spins slowly on idle when clutch not engaged? 15XL motor draw maximum 1.5A@noload and spinning freely on low throttle takes even less and maximum spins freely maybe 2-3% of hole run, just then you start run and slowing down to allmost dead stop, thats it! On Helis motor spins on 80% trottle all the time until battery dump, nothing happening :)
I dont understand how I can dial out throttle to eliminate soft start? Maybe we speak same but understand difrently? Maybe he doing same dialing throttle to 40% then motor start spin and on ground it not move? Did you ever played with this ESC? I do last week on (6S version), tried different ways settings and etc just no luck. It responds immediatly only then motor spins. I have opposite feelings :) that this may work. And anyway I will buy MMM for truggy and current MM will be unused, anytime i can go to 4S.
If "HV project" starts I will inform

spinning without the clutch engaged would be a no load situation, and motors heat up very fast with no load, as all the excess energy is disipated as heat, also, having current constantly flowing through an esc just sounds bad to me. If they are passing current they are meant to be moving for cooling airflow. Thethrottle trim is basically the same idea as yours, just without the motor spinning. Adjust it until the motor just starts to spin, then back off 1 percent so the motor does not spin at neutral.

I have set it as forward as I can without the motor spinning and the problem is still terrible. Yes I set the throttle range. Me and my bro both have one in seperate cars, and have both tried all kinds of weird and wonderful methods of getting rid of the delay and cant manage too... Maybe theres different kinds of software on them or something? I'll have to get a vid and try and demonstrate what I mean.