Which Controller for My Application?

[RC-Monster Mike]

Make sure cvds and upgraded center drive shafts, diffs and an upgraded tranny idler gear make the list. You WILL need these parts with this kind of power.

[luihed]

What do you guys think of the batteries he chose? Im thinking of getting me a set of those Thunder Power as well........

[Rusty]

Originally posted by C.H.U.D.
I have a box *full* of extra stock Traxxas parts...mostly lower control arms and bulkheads. :D


thx again for your help. I'll put my order in tonight or tomorrow morning.

Your putting this system in a stock truck?!?! Your Drivetrain is gonna get eaten alive with that much voltage going through that motor. I sure hope your drivetrain has been upgraded to handle this power, if not you may want to consider it.

[HotnCold]

Take a couple of pics of the diff gears when you get done - LOL - The power that thing is going to put to the stock drivetrain will be insane.

Originally posted by HotnCold
Take a couple of pics of the diff gears when you get done - LOL - The power that thing is going to put to the stock drivetrain will be insane.

Anybody like Twizzlers?

The drivetrain will be on order this week or next.

[rcjmaxx]

Originally posted by RC-Monster Mike
Increased torque is not optional with high voltage brushless motors! It will happen no matter what. The xl3100 will run a bit hot at that voltage and will be too powerful to handle in my opinion. As I said, the xl2400 on 22.2 volts will achieve your speed desires with the proper gearing, but will run cooler. The xl2000 would be my choice. ASgain, this will provide plenty of speed/power, but will have better runtimes and cooler operation vs. the xl3100. I doubt you will see 50 mph on a racetrack anyways (40mph if your lucky).

Hey Mike you say both the xl2000 and xl2400 are great at 22.2 volts but you prefer the xl2000,whats the performance difference between these two motors? Thanks

[Serum]

The XL2000 will give you a better runtime, the 2400 will hit 50000 rpms, the XL2000 is a bit easier on both your controller and drivetrain. The 2400 will draw much more current as well. You can gear the 2000 a bit higher than the 2400.

Lehner calculates the kv of the motor under load, unlike Feigao.

[rcjmaxx]

Thanks

[RC-Monster Mike]

Serum pretty much spoke my mind to the tee(thanks, Rene!). The xl2000 is a better choice for this voltage. your drive train will need the mods regardless of the motor you go with.

Thanks for all the input.

I think the key factor I need to consider is that (as Mike indicated) Lehner measures Kv under load. 50000 RPM is where I want to be (based on final drive and weight) so I'll make the 2400 (22.2v*2400=53280) my baseline and move up or down from there.


thx!

[luihed]

Whats the 2400 equivalent on a feigao, 7XL or 8XL.... CHUD, what kind of chassis do ou have? those packs are pretty big....

[RC-Monster Mike]

9L or 13s would be the closest feigao equivilent

Originally posted by luihed
Whats the 2400 equivalent on a feigao, 7XL or 8XL.... CHUD, what kind of chassis do ou have? those packs are pretty big....

I have a g-maxx CF chassis. The battery packs I want are

(W)50mm x (L)185mm x (H)29mm

or

(W)2in. x (L)7.3in. x (H)1.1in.

I will need to go EXT chassis if I can't get the pack under the steering servo (its very close, so I'll have to get a pack in my hands to get a real measurment). Nonetheless I'll be building custom battery cups out of fiberglass to hold whichever packs I end up purchasing.

Actually I'm still debating whether or not I want the 8000mah or something less (less weight). The 8000mah are 16.6oz, slightly more than 7-cell 3300's. 4000mah are half that. The weight of the 8000mah may be a diminishing return in runtime.

With the motor and battery weight reducation of the 4000's (as long as I don't go too crazy on the motor :D) my truck will be a good performer...w/ regards to runtime that is. My goal is to run a 30 minute main w/ the nitro's. I don't believe w/ the speed I want the 4000's will be enough.

'sides, I'm looking more towards the edge of the envelope (not the total edge, though) in performance than the "safe" known good configurations. Pushing it is the best way to find the "bottleneck" (if you will). Fixing that bottleneck will lead you to the next bottleneck, so on and so forth.

There's a sweet spot combination of weight, mah, voltage, rpm/v, drive ratio, etc. You only get there by calculating, testing, and measuring.

Mostly this crap is just fun to me.

[RC-Monster Mike]

I am right there with you! I don't think you will get a 30 minute runtime with 4000mah packs without a battery change or so. If you use high enough voltage, you can get a pretty good runtime with 4000 mah, especially on a short track with low gearing. For a 30 minute main, you will also have the challenge of keeping the motor cool (think fan, heatsink etc.), especially in the summer. A large motor should be in the cards (larger than the "s" Feigao or basic xl). I am thinking "xl" or a nice 1940 Lehner.

[luihed]

Originally posted by RC-Monster Mike
9L or 13s would be the closest feigao equivilent

I dont get it..... the 9L and 13s are smaller motors than the 7XL and I thought the 7XL is too hot for 20 cells:C: .... I have a 7XL right now, can I run 22.2v on it?

Im definately gonna run 22.2v lipo too but I still dont have a clue to what motor will give me the fasted speed..... I know its 2400 or 2000 for teh lehner or 8XL for the feigao, but for some reason 2000 or 2400 is not the same as 8XL..... Im too confused.....:C: