Higher kv vs. taller gearing

[zeropointbug]

Originally Posted by BrianG

Feigaos are 2 pole, as are MM motors and LMT motors.

The "35k rule" is basically for the Feigaos as they tend to lose efficiency rapidly over that and simply heat up. Motors like the Neu and LMT are higher quality and seem to run just fine at higher rpms. Usually, I like to stick to max rpms that are around 75% or less than the max rpm rating.

hehe... I wonder how motors (such as Neu) would perform at the 'rated' rpm. 60,000rpm max for the 15xx motors... I think we would be a little over our heads no doubt!

They would perform great if you could gear that to sane levels. The Neu 1900 series is rated to 30k RPM max which is how I run mine. :)

[zeropointbug]

Cool, what kind of temps do you get? I hear the 19xx are less efficient than 15xx motors.

Cool enough to keep a hand on it. :) I haven't measured with a temp gauge yet.

Where did you hear that? I plan to run mine with a DPR soon. Curious to know what the numbers are.

[sleebus.jones]

Originally Posted by B15

My mamba has holes through the case with 25mm pusher/ puller fans

Wow, that's a lot of work to be able to run inefficiently!

I'm not slamming you, but take a step back for a minute and think about what's going on. All that heat you are blowing out of there (innovative solution, BTW!) is all wasted power/energy. A perfectly efficient motor wouldn't generate any heat. If you are making enough heat to require a setup such as you describe, that's a lot of runtime being blown out the fans!

The solution to heat is higher voltage. If you can't run higher voltage, you're pretty much going to be stuck with any heat problems you may have. Dropping amp draw is the way to reduce heat, and you can really only do that by lowering the load on the motor (gearing down) or going to a higher voltage. That's pretty much it.

Finnster on here is a perfect example of this: he runs 10S, his truck is a beast, and it doesn't get much more than warm to the touch. My 1/8 buggy that I run 5S in with a 10XL barely gets warm at all, and has enough power to lay rubber on concrete. I'm going to make a 6S pack for it next.

So do you think my mamba would run cooler on 5s, even though its not rated for it? And is there an ESC that wouldnt make any heat? I thought even the $300 quarks had heat issues. Would an MGM run cooler?
Im going to upgrade to an HV setup in this buggy someday, Ive been wanting an MGM 9032 on 8-9s running a Neu. But now Im going to wait to see how the MMM does, since it sounds like thats going to be a lot cheaper.

[BrianG]

Some people have had luck running 5s on a MM, some haven't. And the new version certainly won't.

All ESCs are going to create heat because of the currents involved and the switching rise time of the FETs. The Quarks have heat issues only because of the crappy thermal pad they use. Once properly modded (which may kill your warranty), and add a little extra heatsinking (the case is not a proper heatsink), they run fine. Some of the Quark's heat problem may be in the software because they operate differently (better IMO) than other ESC in how they control the motor.

MGMs do run cooler from all reports, if you can get by the reverse/brake issue.

Your best bet for a relatively inexpensive ESC would probably be the MMM if you can wait...

Turns out Im an idiot, my 7xl wasnt dead. I hadnt ground a flat spot on the shaft, so the pinion setscrew cut a ring all the way around the shaft. I saw that the motor was revving but the pinion wasnt moving (even though the set screw was tight), so I assumed it did the same thing my 380c did. So now Ill probably wait till the mmm comes out before I do anything different with this thing.