Brushless Motor Clarification
07-18-2017, 10:10 PM
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Brushless Motor Clarification
Hey guys I have an Exceed Sunfire (very first hobby grade rc car) and a Traxxas Slash 2wd (Love that truck),.....I've bought 3 Castle Creations Motor/ESC Combos (I have another truck but its out of commission because I cant find the Pinion gear online anywhere, so that freakin sucks and it doesn't help that I'm over seas for a deployment so its going to take a minute for parts to get to me anyway) 2, 4600kv motors and 1, 3800kv. I have a 4600kv in the Sunfire and the 3800kv in the Slash. Now to get to my point I've been reading a lot of forums and watching plenty of YT videos on different brushless systems and I'm kinda stuck on the knowledge, what I've found out so far is that the lower the Kv the more torque the motor has?? Do anybody have experience with lower kv Castle Creation motors and the Mamba Max Pro ESC? What makes that ESC better? Lower Kv vs Higher Kv? Any experience with Hobbywing ESC's ? I see that the lower kv Motors are bigger than higher kv motors Why is that? Just a few General questions I have this is one of favorite hobbies and out here in the desert is like the perfect place for this Hobby we also have a track built by Soldiers from previous years ago that we hold races on each month (Races are determined by drivetrain i.e. 2wd/4wd) I just want to get the upper advantage and beat everyone!! lol thanks
07-19-2017, 03:19 AM
#2
You also have to look at the size of the motor. 1/10 scale, 1/8 scale differ a lot. 540 (3650 = 36x50mm) and 550 (3656 = 36x56mm) sized motors are used in 1/10 scale RCs. They do vary in sizes and 540/550 are more of a generallized size. 1/8 scale RCs use larger motors to move...larger platforms...more weight. Motor sizes around 4068 (40x68mm) and larger are used in 1/8 scale buggies/truggies. Lower kV and more voltage is always more efficient and why you see 4S LiPo packs generally used in 1/8 RCs.
Off to work I go...
Off to work I go...
07-19-2017, 11:28 AM
#3
Greetings, sir, and thanks for your service. Be careful out there.
It's really easy to get "info overload" when researching this hobby online. Exceed, isn't that HobbyPartz/NitroRCX's brand? Can't go too wrong with a Slash (unless you have the high-CG chassis). But if you're new to this, yeah, there's a lot of jargon to assimilate. But you military guys are used to peculiar jargon, right?
Lemme take your questions one at a time, more or less:
Motor KV - You're right, the lower the KV the more torque the motor has, the higher KV, the more RPM it has. "KV" means "RPM per Volt". I know, go figure. The real explanation is waaay too complicated, and for most intent, that "definition" is close enough for most of us, unless you're getting into motor efficiencies and internal resistances and back-EMF..... In general, the bigger the size of the motor can, the more torque (power) it will have, relative to a motor of the same KV but a smaller can dimension. (The 540 vs 550 thing) Likewise as I said, the lower a motor's KV the torque-ier it is compared to the same size motor can, but one with a higher KV. Let's not get ourselves confused by the "T-rating vs KV" either. ("T" or "Turn" -rating comes from the brushed motor tech. The number of turns of wire around the Stator.) And the fact that some motors are marked with BOTH.
So which motor you choose for a particular platform depends, loosely, on the size and weight of the car in question.
What makes the MMP a "better" ESC? - I don't know. Maybe its power handling capabilities and wide motor range? Castle IS known for making excellent motors. I've had some sketchy older Castle Sidewinder ESCs, but their Sidewinder 3 seems to be a lot better and reliable as any. Castle's sensorless motor startup routine used by the firmware in the ESC is one of the smoothest out there. The MMP can handle up to 6S, I believe. And you know, it's a Castle-made ESC and 1000KV(?) motor that Traxxas uses in their 100MPH X-01. HobbyWing also makes good systems, I've used their smaller EZrun systems. Hard to beat the price if yer just messin' around. Their higher-end Xerun systems are probably better quality for racing. And there are others.
Lemme throw another one at ya: 2-pole motors vs 4-pole. I believe most if not all of Castle's motors are 4-pole. Meaning that the rotor has not just a North and South magnetic pole, it has two of each. Or, 4-poles. Correspondingly the windings in the motor can are designed to work with a 4-pole rotor. This makes the motor run and start up more smoothly, and in general, gives you more torque compared to a 2-pole motor.
And all these things can affect speed. But you also have to consider GEARING. You have to have some care in swapping in a new motor system. A car's gearing is carefully calculated by it's designers for the given motor and tire/wheel size and type of drive train. It's helpful to have a digital IR thermometer to monitor your motor and ESC temps, to help you determine proper gearing. You don't want your motor to get over 180F, and best to keep it in the 150F-or-less range. So get yourself a selection of pinions from Robinson Racing or somewhere so you can go up or down a tooth or two if you need.
It's really easy to get "info overload" when researching this hobby online. Exceed, isn't that HobbyPartz/NitroRCX's brand? Can't go too wrong with a Slash (unless you have the high-CG chassis). But if you're new to this, yeah, there's a lot of jargon to assimilate. But you military guys are used to peculiar jargon, right?
Lemme take your questions one at a time, more or less:Motor KV - You're right, the lower the KV the more torque the motor has, the higher KV, the more RPM it has. "KV" means "RPM per Volt". I know, go figure. The real explanation is waaay too complicated, and for most intent, that "definition" is close enough for most of us, unless you're getting into motor efficiencies and internal resistances and back-EMF..... In general, the bigger the size of the motor can, the more torque (power) it will have, relative to a motor of the same KV but a smaller can dimension. (The 540 vs 550 thing) Likewise as I said, the lower a motor's KV the torque-ier it is compared to the same size motor can, but one with a higher KV. Let's not get ourselves confused by the "T-rating vs KV" either. ("T" or "Turn" -rating comes from the brushed motor tech. The number of turns of wire around the Stator.) And the fact that some motors are marked with BOTH.
So which motor you choose for a particular platform depends, loosely, on the size and weight of the car in question.What makes the MMP a "better" ESC? - I don't know. Maybe its power handling capabilities and wide motor range? Castle IS known for making excellent motors. I've had some sketchy older Castle Sidewinder ESCs, but their Sidewinder 3 seems to be a lot better and reliable as any. Castle's sensorless motor startup routine used by the firmware in the ESC is one of the smoothest out there. The MMP can handle up to 6S, I believe. And you know, it's a Castle-made ESC and 1000KV(?) motor that Traxxas uses in their 100MPH X-01. HobbyWing also makes good systems, I've used their smaller EZrun systems. Hard to beat the price if yer just messin' around. Their higher-end Xerun systems are probably better quality for racing. And there are others.
Lemme throw another one at ya: 2-pole motors vs 4-pole. I believe most if not all of Castle's motors are 4-pole. Meaning that the rotor has not just a North and South magnetic pole, it has two of each. Or, 4-poles. Correspondingly the windings in the motor can are designed to work with a 4-pole rotor. This makes the motor run and start up more smoothly, and in general, gives you more torque compared to a 2-pole motor.
And all these things can affect speed. But you also have to consider GEARING. You have to have some care in swapping in a new motor system. A car's gearing is carefully calculated by it's designers for the given motor and tire/wheel size and type of drive train. It's helpful to have a digital IR thermometer to monitor your motor and ESC temps, to help you determine proper gearing. You don't want your motor to get over 180F, and best to keep it in the 150F-or-less range. So get yourself a selection of pinions from Robinson Racing or somewhere so you can go up or down a tooth or two if you need.
07-19-2017, 02:08 PM
#7
If you go check out Castle Creations, and various threads thoughts on lower Kv/torque "content"....it will make your head spin. Back in the day of brushed motors it was more noticeable. I was deep into reading last week on the subject. Lost the thread on it. Just one of the many threads out there...Real-World Effects of Brushless Motor Kv Rating - RCU Forums - RC...
The Kv does not effect torque. Here is a great explanation from Castle and has lead to some controversy:
A high power capable brushless motor in electrical engineering and physics terms, has unlimited torque. We live in “the real world” so technically for us that’s not totally true, but – a brushed motor has a torque level that due to its design has an upper limit, regardless of how much power is being applied to it. That limit is low enough that you can see it clearly on an average track On the other hand, a high power brushless motor’s limit to torque in an RC vehicle is not within the bounds of the motor itself so much, but rather falls on the ability of the battery to deliver current to it. We generally don’t describe these motors in terms of “one has more torque than the other”, but rather “the 7700Kv motor is faster and draws more current than a 5700Kv motor in the same vehicle”. It draws more current, because it’s making the car go faster and doing more work than the 5700 motor is. As long as the batteries used are very good at supplying current without an excess of voltage depression (low internal resistance is good) both motors will appear to have the same torque, even though one is much faster than the other. Battery technology is constantly improving, and the first thing you’ll notice when you use a very good battery pack (or perhaps trying a Lipo pack for the first time) with these systems is a more “punchy” feel when you accelerate. The faster you set up the car to go at full throttle, the more reliant you are on good batteries to flow that current into the motor and maintain acceleration performance. So think of torque as a function of battery capability only.
The Kv does not effect torque. Here is a great explanation from Castle and has lead to some controversy:
A high power capable brushless motor in electrical engineering and physics terms, has unlimited torque. We live in “the real world” so technically for us that’s not totally true, but – a brushed motor has a torque level that due to its design has an upper limit, regardless of how much power is being applied to it. That limit is low enough that you can see it clearly on an average track On the other hand, a high power brushless motor’s limit to torque in an RC vehicle is not within the bounds of the motor itself so much, but rather falls on the ability of the battery to deliver current to it. We generally don’t describe these motors in terms of “one has more torque than the other”, but rather “the 7700Kv motor is faster and draws more current than a 5700Kv motor in the same vehicle”. It draws more current, because it’s making the car go faster and doing more work than the 5700 motor is. As long as the batteries used are very good at supplying current without an excess of voltage depression (low internal resistance is good) both motors will appear to have the same torque, even though one is much faster than the other. Battery technology is constantly improving, and the first thing you’ll notice when you use a very good battery pack (or perhaps trying a Lipo pack for the first time) with these systems is a more “punchy” feel when you accelerate. The faster you set up the car to go at full throttle, the more reliant you are on good batteries to flow that current into the motor and maintain acceleration performance. So think of torque as a function of battery capability only.
07-19-2017, 07:19 PM
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Greetings, sir, and thanks for your service. Be careful out there.
It's really easy to get "info overload" when researching this hobby online. Exceed, isn't that HobbyPartz/NitroRCX's brand? Can't go too wrong with a Slash (unless you have the high-CG chassis). But if you're new to this, yeah, there's a lot of jargon to assimilate. But you military guys are used to peculiar jargon, right? Lemme take your questions one at a time, more or less:
Motor KV - You're right, the lower the KV the more torque the motor has, the higher KV, the more RPM it has. "KV" means "RPM per Volt". I know, go figure. The real explanation is waaay too complicated, and for most intent, that "definition" is close enough for most of us, unless you're getting into motor efficiencies and internal resistances and back-EMF..... In general, the bigger the size of the motor can, the more torque (power) it will have, relative to a motor of the same KV but a smaller can dimension. (The 540 vs 550 thing) Likewise as I said, the lower a motor's KV the torque-ier it is compared to the same size motor can, but one with a higher KV. Let's not get ourselves confused by the "T-rating vs KV" either. ("T" or "Turn" -rating comes from the brushed motor tech. The number of turns of wire around the Stator.) And the fact that some motors are marked with BOTH. So which motor you choose for a particular platform depends, loosely, on the size and weight of the car in question.
What makes the MMP a "better" ESC? - I don't know. Maybe its power handling capabilities and wide motor range? Castle IS known for making excellent motors. I've had some sketchy older Castle Sidewinder ESCs, but their Sidewinder 3 seems to be a lot better and reliable as any. Castle's sensorless motor startup routine used by the firmware in the ESC is one of the smoothest out there. The MMP can handle up to 6S, I believe. And you know, it's a Castle-made ESC and 1000KV(?) motor that Traxxas uses in their 100MPH X-01. HobbyWing also makes good systems, I've used their smaller EZrun systems. Hard to beat the price if yer just messin' around. Their higher-end Xerun systems are probably better quality for racing. And there are others.
Lemme throw another one at ya: 2-pole motors vs 4-pole. I believe most if not all of Castle's motors are 4-pole. Meaning that the rotor has not just a North and South magnetic pole, it has two of each. Or, 4-poles. Correspondingly the windings in the motor can are designed to work with a 4-pole rotor. This makes the motor run and start up more smoothly, and in general, gives you more torque compared to a 2-pole motor.
And all these things can affect speed. But you also have to consider GEARING. You have to have some care in swapping in a new motor system. A car's gearing is carefully calculated by it's designers for the given motor and tire/wheel size and type of drive train. It's helpful to have a digital IR thermometer to monitor your motor and ESC temps, to help you determine proper gearing. You don't want your motor to get over 180F, and best to keep it in the 150F-or-less range. So get yourself a selection of pinions from Robinson Racing or somewhere so you can go up or down a tooth or two if you need.
It's really easy to get "info overload" when researching this hobby online. Exceed, isn't that HobbyPartz/NitroRCX's brand? Can't go too wrong with a Slash (unless you have the high-CG chassis). But if you're new to this, yeah, there's a lot of jargon to assimilate. But you military guys are used to peculiar jargon, right?
Lemme take your questions one at a time, more or less:Motor KV - You're right, the lower the KV the more torque the motor has, the higher KV, the more RPM it has. "KV" means "RPM per Volt". I know, go figure. The real explanation is waaay too complicated, and for most intent, that "definition" is close enough for most of us, unless you're getting into motor efficiencies and internal resistances and back-EMF..... In general, the bigger the size of the motor can, the more torque (power) it will have, relative to a motor of the same KV but a smaller can dimension. (The 540 vs 550 thing) Likewise as I said, the lower a motor's KV the torque-ier it is compared to the same size motor can, but one with a higher KV. Let's not get ourselves confused by the "T-rating vs KV" either. ("T" or "Turn" -rating comes from the brushed motor tech. The number of turns of wire around the Stator.) And the fact that some motors are marked with BOTH.
So which motor you choose for a particular platform depends, loosely, on the size and weight of the car in question.What makes the MMP a "better" ESC? - I don't know. Maybe its power handling capabilities and wide motor range? Castle IS known for making excellent motors. I've had some sketchy older Castle Sidewinder ESCs, but their Sidewinder 3 seems to be a lot better and reliable as any. Castle's sensorless motor startup routine used by the firmware in the ESC is one of the smoothest out there. The MMP can handle up to 6S, I believe. And you know, it's a Castle-made ESC and 1000KV(?) motor that Traxxas uses in their 100MPH X-01. HobbyWing also makes good systems, I've used their smaller EZrun systems. Hard to beat the price if yer just messin' around. Their higher-end Xerun systems are probably better quality for racing. And there are others.
Lemme throw another one at ya: 2-pole motors vs 4-pole. I believe most if not all of Castle's motors are 4-pole. Meaning that the rotor has not just a North and South magnetic pole, it has two of each. Or, 4-poles. Correspondingly the windings in the motor can are designed to work with a 4-pole rotor. This makes the motor run and start up more smoothly, and in general, gives you more torque compared to a 2-pole motor.
And all these things can affect speed. But you also have to consider GEARING. You have to have some care in swapping in a new motor system. A car's gearing is carefully calculated by it's designers for the given motor and tire/wheel size and type of drive train. It's helpful to have a digital IR thermometer to monitor your motor and ESC temps, to help you determine proper gearing. You don't want your motor to get over 180F, and best to keep it in the 150F-or-less range. So get yourself a selection of pinions from Robinson Racing or somewhere so you can go up or down a tooth or two if you need.
07-19-2017, 08:19 PM
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And Yes Exceed is sold through Nitrorcx they Promote that Brand a lot I like their Cars and trucks it's just when you take the Sunfire which is considered 1/10 and put it next to the Slash which is also 1/10, the Size difference is tremendous the sunfire is a lot smaller
07-22-2017, 07:11 AM
#10
Yeah, size vs scale is also inconsistent. But they are consistent within their own platform type. That is, all short course trucks will be the same size, and all stadium trucks will be the same size. But compare for instance my HoBao Hyper TT and it's sister, the Hyper SCT. The SCT is considerably longer, but they are both considered 1/10 scale.
Normally, I recommend against Exceed because they have no local distributors in the U.S. other than HobbyPartz/Nitro RCX, and getting replacement parts can take a long time. But in your situation, you're getting everything online anyway, so it's kind of a wash. Glad you like it tho.
Normally, I recommend against Exceed because they have no local distributors in the U.S. other than HobbyPartz/Nitro RCX, and getting replacement parts can take a long time. But in your situation, you're getting everything online anyway, so it's kind of a wash. Glad you like it tho.
