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06-19-2013, 01:12 PM | #1 |
Pebble Pounder Join Date: Aug 2011 Location: seattle
Posts: 161
| Why brushless (inrunner) motors aren't best for crawling
I think this could be the most overlooked and least talked about reason why brushless motors are NOT BEST for crawling, and why they cog.its my understanding that brushless motors have a minimum rpm that coincides with voltage and number of poles. The higher the kv and the lower the number of poles, the higher the minimum rpm will be. Load also has a big play. Brushed motors are less effected by load. This is why John Holmes is developing a sensored outrunner that has up to 14 poles. With a set kv, the more poles a motor has, the more torque it has, and also it has the less of a chance to stall between poles because the poles are closer and/or smaller. Please correct me if I'm wrong. I feel I am starting to really understand brushless motors and would like to help others understand in more detail as well. |
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06-20-2013, 11:53 AM | #2 |
Quarry Creeper Join Date: Aug 2009 Location: Gamecock Country
Posts: 284
| Re: Why brushless (inrunner) motors aren't best for crawling
I'm running a 890kv, 540 size, outrunner, 12 pole, nonsensored on 9.8 volts(about to be 11.1 3s lipo). This thing is a torque monster! I have never understood why everyone doesn't run an outrunner for crawling. Have run this setup for a couple of years with no problems. An outrunner with a low enough kv. doesn't need to be sensored. Run mine on a Quark procar 33a esc and have not came close to cogging. Have never heard of a Quark procar 33a cogging. My buddies and I have pretty much tried most esc/motor crawling combos between all of us and I have always stuck with my outrunner. As far as brushless inrunners go, I've run them in many touring cars, race trucks and monster/basher trucks with great results, but not so much with crawling or any slow application.
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06-20-2013, 12:57 PM | #3 | |
RCC Addict Join Date: Jul 2012 Location: Oreganastan
Posts: 1,151
| Re: Why brushless (inrunner) motors aren't best for crawling Quote:
You have my interest. Exactly what motor (brand / model?) | |
06-20-2013, 12:57 PM | #4 |
I wanna be Dave Join Date: Mar 2007 Location: roland,ar
Posts: 5,981
| Re: Why brushless (inrunner) motors aren't best for crawling
I run a tekin 13.5t brushless SENSORED motor with 13mm torque rotor..smooth as butter no cog..on 3s..MMP esc. sensorless motors cog/stall.. sensored motors are smoother in lowend control.. I have a HH revolver outrunner I ran for awhile... just to damn noisy.. |
06-20-2013, 01:01 PM | #5 |
RCC Addict Join Date: Jul 2012 Location: Oreganastan
Posts: 1,151
| Re: Why brushless (inrunner) motors aren't best for crawling |
06-20-2013, 01:05 PM | #6 |
Rock Crawler Join Date: May 2012 Location: Upland
Posts: 901
| Re: Why brushless (inrunner) motors aren't best for crawling
where can we find outrunner's that fit our needs? Do they make outrunners that mount to the output end of the motor?
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06-20-2013, 01:16 PM | #7 |
Pebble Pounder Join Date: Aug 2010 Location: Magnolia, TX
Posts: 108
| Re: Why brushless (inrunner) motors aren't best for crawling
I've had a sensored 540 inrunner in my Wraith since the beginning. Works perfectly. I had a sensorless 540 in my Exo just to mess with it until the sensored motor showed up and it sucked, but with the sensored motor in there everything is great. I don't see any need to change a thing in either of them.
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06-20-2013, 01:18 PM | #8 |
I wanna be Dave Join Date: Jul 2009 Location: Rancho Relaxo. California. USA. Earth.
Posts: 3,292
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I ran a couple outrunners for awhile. The startup was hard to get accustomed to. Everything else was there.
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06-20-2013, 01:23 PM | #9 |
I wanna be Dave Join Date: Mar 2007 Location: roland,ar
Posts: 5,981
| Re: Why brushless (inrunner) motors aren't best for crawling |
06-20-2013, 01:28 PM | #10 |
I wanna be Dave Join Date: Mar 2007 Location: roland,ar
Posts: 5,981
| Re: Why brushless (inrunner) motors aren't best for crawling
Sensored inrunner..novak ballistic..17.5t outrunner HH revolver..1000kv |
06-20-2013, 01:33 PM | #11 |
I wanna be Dave Join Date: Mar 2007 Location: roland,ar
Posts: 5,981
| Re: Why brushless (inrunner) motors aren't best for crawling |
06-20-2013, 01:34 PM | #12 | |
RCC Addict Join Date: Jul 2012 Location: Oreganastan
Posts: 1,151
| Re: Why brushless (inrunner) motors aren't best for crawling Quote:
sensorless inrunner motors cog/stall.. sensored motors are smoother in lowend control.. sensorless outrunner motors much less cog /stall | |
06-20-2013, 01:37 PM | #13 | |
Pebble Pounder Join Date: Aug 2011 Location: seattle
Posts: 161
| Quote:
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06-20-2013, 01:40 PM | #14 |
Pebble Pounder Join Date: Aug 2011 Location: seattle
Posts: 161
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06-20-2013, 02:50 PM | #15 |
I wanna be Dave Join Date: Jul 2009 Location: Rancho Relaxo. California. USA. Earth.
Posts: 3,292
| Both scorpions, 22 and 30 series. Iirc 1200kv and 890kv respectively. On 3s and 4s. Btw not that the startup was cogging, the ramped startup just felt odd. Last edited by Meatwad; 06-20-2013 at 02:53 PM. |
06-20-2013, 03:55 PM | #16 | |
I wanna be Dave Join Date: Mar 2007 Location: roland,ar
Posts: 5,981
| Re: Why brushless (inrunner) motors aren't best for crawling Quote:
it will also depend on how its geared.. if your running 32p gears or 48p. I can fine tune with gears if my kv is in the right range. I have been into Rc crawling since '06.. I have ran just about every combo I can. brushed motors are smoother..no question. depends on what you call crawling as well.. we talking snails pace or what? | |
06-20-2013, 04:38 PM | #17 |
Pebble Pounder Join Date: Aug 2011 Location: seattle
Posts: 161
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Yes. Sometimes you need that snails pace to get out of a bad spot. When a motor starts at a higher rpm it can be "touchy"or "jumpy" off the line. That could send you into a gate, off the side of a rock, or down a cliff like my wraith did lol.
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06-20-2013, 04:51 PM | #18 |
Pebble Pounder Join Date: Aug 2011 Location: seattle
Posts: 161
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There is a more "technical" line at my local spot I always can make with my brushed setup. Full confidence! When I went brushless I would make it one out of three times, maybe. It wasn't pretty looking either. There also were lines I just couldn't make. I geared Dow to fix it and there went my wheel speed. Couldn't make the hill climbs I could before. Also still not as slow of a startup speed as brushed.
Last edited by colebz; 06-20-2013 at 05:31 PM. |
06-20-2013, 06:18 PM | #19 |
Suck it up! Join Date: Mar 2008 Location: Arkansas
Posts: 11,652
| Re: Why brushless (inrunner) motors aren't best for crawling
ESC programming and construction can effect startup as well. My first attempt at brushless crawling was with an old v1 sidewinder. My latest attempt was with an LT4. They behave way, way differently. |
06-20-2013, 06:51 PM | #20 |
I wanna be Dave Join Date: May 2007 Location: Fairfield ME
Posts: 3,886
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