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Torque

Old 04-01-2015, 11:58 AM
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rcblack79
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Default Torque

Can anyone recommend a good esc that can handle 6+ poles im building a scratch made rc monster truck and I need torque, I want to use a 880kv outrunner on at lease 6s lipo, thanks for any input
Old 04-01-2015, 05:22 PM
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6 poles, 6S, and 880kv? That thing's gonna be a seriously serious power house! Damn!
Old 04-01-2015, 05:45 PM
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This is the biggest and most powerful ESC out there. If this won't work, nothing will. Maybe a motor controller, but that would a pain to get to work with a receiver.

http://www.horizonhobby.com/CSE01000...T5QxoCaxHw_wcB
Old 04-02-2015, 06:53 PM
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The Castle MMXL2 collector linked will work with a 6 pole or even an 8 pole outrunner. The smaller MMM2 will also work with outrunners or any motor with 8 poles, I've seen it done multiple times. I haven't seen anyone using an outrunner on a nonCastle land esc or anyone try more than 8 poles on a Castle land esc though. Outrunners do like more timing so an esc with adjustable timing is a must.

What determines whether an esc will work or not is how fast it can switch the phases of the esc. With a 4 pole motor each of the 3 phases of the motor is fired 4 times per revolution for a total of 12 times per revolution that the esc is firing the phases of the motor. With an 8 pole motor that's 24 times per revolution it fires the motor phases. Every esc can fire the phases only so fast, the old Traxxas VXL-3s esc was famous for running 4 pole motors at about half speed because it couldn't fire the phases fast enough.

But thankfully you can do some easy math to figure out if an esc can keep up. Mainstream 6s capable land esc's typically are available in a combo with a motor that's about 2200kv. Using 22.2v nominal for 6s that 2200kv motor would be spinning almost 49,000rpm and they wouldn't include the esc with that motor if it couldn't fire the motor phases fast enough to achieve that rpm. Your 880kv motor would spin up to almost 20,000rpm on 22.2 volts, that's max rpm. I'm not going to do the math and figure out how many times the motor phases are fired per second for each motor and I don't have too. An 8 pole requires the phases to be fired twice as many times per second as a 4 pole to achieve a specific rpm. So 20,000rpm with the 8 pole is equal to the same number of phases fired per second as the 4 pole at 40,000rpm and we know the esc is capable of at least 49,000rpm. Hope this helps.

Last edited by Maj_Overdrive; 04-02-2015 at 07:17 PM.
Old 04-02-2015, 07:14 PM
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I haven't read these threads in awhile and they are a bit dated but hopefully they'll help out a bit. The first is a 1390kv 8 pole outrunner in a Revo on 6s with a Castle MMM. The second is an outrunner info thread.
http://www.rc-monster.com/forum/showthread.php?t=27799
http://www.rc-monster.com/forum/showthread.php?t=29583
Old 04-03-2015, 06:07 AM
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rcblack79
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Thanks for the reply, ill purchase the cc mamba monster xl and ill find a 8 pole heli or plane motor to run I also know hobbywing esc can handle many poles but I want 8s minimum
Old 04-03-2015, 06:22 AM
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The Castle XL2 is really one of their plane/heli esc's with a heat sink and firmware with brakes and startup routines for ground use. So it can definitely handle an outrunner without issue.

You could use a different air esc as well. But then you need mechanical brakes and either a stick radio or a pwm adapter like a Pistix to use a pistol grip radio. The Castle XL2 is definitely the easiest option if you're ok with 8s max. If you want more than that look into MGM esc's as they have ground specific models with 15s capability. They're the biggest and baddest esc's you can get.
http://www.mgm-controllers.com/cars
Old 04-03-2015, 09:17 AM
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rcblack79
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I saw the mgm esc at kershaw designs and they are not cheap, the mmxl2 will give me what I need, hell on 15s the truck will fly in the air. Lol
Old 04-03-2015, 10:04 AM
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The MGM's are expensive and overkill even for 1/5 scale. But they are the most robust large scale esc out there and you did say at least 8s. You got me really curious about the truck you're building. Be sure to post up some details when you're ready to share.
Old 04-03-2015, 11:07 AM
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Most definitely

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