MMM availibility date dropped!

[jhautz]

Originally Posted by BrianG

IMO, I don't know what the fuss is all about. Yeah, 2200kv is a bit high for 6s, but if you don't want to go that fast, just gear down. For a given battery voltage and vehicle speed (mechanical load) a higher kv motor geared down will draw just as much current as a lower kv motor geared up, and runtime will be about the same. Any efficiency gained by using a low kv motor is lost by gearing high to compensate for lower speeds. Again, this is for a given voltage and vehicle speed.

Plus, spinning a motor a little faster and gearing down is better for the ESC because it has enough rpms at low speed to get adequate back-EMF pulses. A too-low kv motor geared high will spin too slow at low vehicle speeds and may produce cogging. Of course, this theory holds true for better motors like LMTs and Neus (which the CC motors are based off of) - you wouldn't treat Feigaos the same way because of their lower rpm sweet spot.

If geared down and it's still too fast, set the throttle EPA down a tad. Once you get bored with that speed, increase it back up to 100% and you'll be happy again....until max speed becomes boring.

Yes you can make anything "work". But the point is that a 2200kv motor on 6s is FAR from optimal. I personally wouldn't even consider running the motor at almost 50K rpm on a consistent basis. I don't care how great the motor is. That's just asking for problems.

I don't have any data to offer here, but I sure would be interested to see how spinning a 2200kv motor on 6s at ~50K rpm is just as efficient as spinning a 1500kv motor at ~35K rpm. Even with the gearing compensated to drive the vehicle at the same overall speed theoretically. Why wouldn't we all just run all of our motors at 50K rpm then? It creates heat generated by the increased inefficiency. Not to mention really narrowing the gearing window you have to work with. With a high quality motor spinning at a reasonable rpm on the correct voltage the gearing options up and down from the "optimal" setup is quite large. Even with the high end motors once you start taking one of the parameters out side of the optimal range (in this case the rpm) you start to limit your flexibility on the other setup parameters.

I see that they test report that someone gave onthe temps after a hard beating run on 6s and they were still within limits, but now take that gearing and go up or down a coulple teeth. I gaurantee you dont get temps still in spec. If you had a properly matched battery and motor you will gain alot of flexability in your setup.


Bottom line... can you make it work? Yes. Would it be better to have a properly specified motor for the voltage you want to run? Yes. Would I run the 2200kv motor on 6s as an everyday set up. No. Would I spend my money on a system that I know from the get go isnt "right"? NO. Just my opinon.

[lincpimp]

To me the 2200 kv motor looks to be perfect for 5s for normal running, it would be geared slightly lower than an 9xl on 5s, but not much different.

You would then have the option of running it on 6s for speed runs or the like. For track use, most seem to think that 4s and a 2200kv motor is enough, but all they are trying to do is run at nitro speed, mainly cause that is all the track is designed for, and the vehicle may not be able to handle the extra speed.

A lower kv motor like 1800-1900 kv would be optimium for 6s, IMO. I routinely push my 7xl over 35k rpm, truck is geared for 40mph. I see no reason why a higher quality motor could not handle 40k rpm.

On a side note, does anyone here run a 1515 on 6s lipo in a maxx or revo truck? Seems like too much motor, but I guess the gearing will detirmine the load. And the motor should run cooler.

[johnrobholmes]

Why not a 4s or 5s setup? It is just as expensive to get a new battery as it is a (nice) new motor, maybe even cheaper. If they came out with a 1500kv motor we would have just as many complaints that it wasn't fast enough! With the initial 2200kv motor release, the 6s max MMM voltage will be able to squeeze the most out of the system RPM wise. Sure it might not be optimal for every vehicle, but name ONE motor that is.

[jhautz]

Originally Posted by johnrobholmes

Sure it might not be optimal for every vehicle, but name ONE motor that is.

Exactly.


In reality, I personally dont really care what motor they offer at this point. Just get the controller released. Motor chioce is not the problem, there are tons of options for motor choice. Its getting a controller that performs the way we want, and if the controller can handle a 1515 sized motor with those kinds of rpms and vehicle speeds I cant wait to get my hands on one.