I been noticing that on BL motors, amps are fixed numbers and the watts change or vice versa. So if was different number on some motors then I figure they can be changed, yeah? So lets use the Velineon for my example...

Traxxas Velineon 3500
RPM/volt: 3500 (10-turn)
Max RMP: 50,000
Current Ratings: 65A constant / 100A peak/burst
Lipo
25,900 RPM on 2s Lipo 7.4v - 65 Amps @ 481 Watts
38,850 RPM on 3s Lipo 11.1v - 65 Amps @ 721.5 Watts 481/11.1v=43.3


Fixed numbers on the amps, but the watts are different numbers. If I take the amp value 481 Watts from the 7.4v and divide that with 11.1v it gives me 43.3 Amps (481/11.1v=43.3).

*25,900 RPM on 2s Lipo 7.4v - 65 Amps @ 481 Watts
**38,850 RPM on 3s Lipo 11.1v - ??? 43 Amps @ 481 Watts ???

* The 7.4 stays the same and give you clear flat calculation... 65 Amps @ 481 Watts
** The 11.1v amps change and using a higher voltage does give you less amps, but the watts number stays the same as it is on a 7.4v. 11.1v should give you more watts right?

Maybe there are two ways of looking at numbers, I dunno; but on other motors the numbers are different.

Novak Ballistic Racing Brushless Motor 8.5T
Watts: 280
kV: 5000 RPM/volt (unloaded)
Lipo
37,000 RPM on 2s Lipo 7.4v - 37.8 Amps @ 280 Watts - 37.8 Amps X 7.4 = 280 Watts
55,500 RPM on 3s Lipo 11.1v - 25.2 Amps @ 280 Watts - 37.8 Amps x 11.1v = 420 Watts (419.58)

Does it really matter how the numbers are read? And did I explain this right at all?

Ray

http://www.rctech.net/forum/electric...less-dyno.html

Look at the graphs at the beginning of this thread.
Peak wattage properly measured is typically encountered halfway to the max RPMs of the motor, and under extreme exertion (dyno measurements are the motor turning a flywheel with full throttle). It can take 6-7 seconds for that flywheel to get up to speed whereas a typical RC brushless setup gets up to speed in 1.5 to 3 seconds or less.

In reality, for brushless, modified racing or bashing, it's basically an irrelevant number with no real bearing on performance. Manufacturers themselves have no idea how to rate their motors, since a modern 1/10th scale brushless modified motor can pull more than a thousand watts if the conditions are right. So honestly they are just pulling numbers out of their #$$ and putting them out there.

Don't get overly involved with the numbers, staticians don't do too well in this hobby (or in many others).

I remember playing 'ball this weekend and there was one guy telling me how his matrix (newer) did 18bps and mine (a few years old) was only 15bps rated and my friends A-5 was only good for 13bps and that was only with the e-trigger that he didn't even have... so his must be superior and I just started rolling my eyes and thought 'not another one of these guys... why do they always end up being on my team...' It's no different than the guys who buy cameras based on megapixels or the guys who buy computers based on clock speeds, it's become something of an arbitrary number that has only a peripheral bearing on the quality of the setup.

Basically, if you are going to talk theory, always have a problem in mind that you are trying to solve; don't overthink things. There's a lot of things that don't really make perfect sense in this hobby, just the way it is.

LOL, that makes a lot of sense. So what should I look for when buying BL motors, just ask around the forums and see what other people think from their experiences? Thanks for the help

Does it take more voltage to reduce amp draw though?

More Voltage = Less Amps = More Watts?

Ray

It can, but it gets really complicated really fast. More voltage can mean more speed, which can then mean more drag, which can actually make for more current draw. It "all just depends" in reality, there's too many un-stated variables. A lot of the current draw is just how you drive it, how you gear it, how fast your running and on what terrain. If you're on a tough terrain, doubling you speed and mean 4x the current or more.

Basically just decide what you are trying to do, ie. what vehicle, how fast in terms of top speed, how much runtime you want, typical terrain you'll be running on, and then post that as in "how do I get here" and you'll get pleanty of useful help from there. Ignore the 'fanboy' posts (ie. I think you should use this b'cos I used it and it's the best, it rocks!) and look for a majority or consensus, most of the advice you'll get tends to be pretty good.

Very helpful,thanks so much!

Ray