Instead of just posting the links I went ahead and posted both articles here for you guys to read although Rolex Copied the second one and stockied it at the top so you may have already seen the second one.
Pick the right brushless motor
Whether you are new to electric RC-Cars, been long out of the hobby and now come back again or you normally race nitro cars and want to take a breath of fresh air during the winter by using electric power, you may be faced by something that is called an Electric Brushless Motor.
As usual we do not bore you with technical or physical terms, mathematic formulas and what not (well, maybe a bit later ...). Those of you who want to dig a bit deeper find all information about how an electric brushless motor (and controller) works here.
Those of you who are more practically orientated my ask: "What motor do I need to suit my needs?" In the first place you have to find out what your needs are. Do you wish to power a small, lightweight on-road car or a heavy 1/8 scale off-road buggy or truck? And how about the speed and runtime you would like to achieve? Is it the blistering super sonic speed you are after? Or are you a runtime junky? The above questions need to be answered before picking the correct brushless motor.
280 or 700?
We promised you not to go into deep in terms of "how brushless motors work" but we have to tell you a bit about the different types and sizes. Normally all (RC-Car) electric motors follow some basic rules when it comes to can sizes. Many, many moons ago the japanese company Mabuchi invented the "RS" called line of brushed electric motors for cars, boats and airplanes. The RS 380 and RS 540 are a, if not THE, synonym for basic electric motors and are still used in many basic RC-Car models from Tamiya, Kyosho and many others. The numbers described the can sizes of the motors and these are still in use with todays modern electric brushless motors. Here's a rundown on the most popular can sizes:
Let's get physical
The 540-size motors are the most common with RC-Cars as they are used for the 1/10 scale competition classes and therefore you may find the largest variety of different motors in this can size. This class of motors also is one of the very few where the so called "Turn" rating is still in use. "Turn" describes how often the copper wire that is used inside the motor, is wounded around the rotor poles (Again we have to refer to the above Wikipedia article for those who don't know who an electric motor works). For the impatient ones of you: The less turns, the more power is generated by the motor. Or even more simple: a 4.5 turn motor is faster than a 21.5 turn motor.
Most of the other motor sizes use a more 'realistic' term to describe the performance of an electric motor: the so called KV rating. KV describes the RPM a motor does per Volt that is put into it. An example: A motor with a KV rating of 5000 used with a 7.4V LiPo battery pack has a (non-load) RPM of 37,000. A motor with a KV rating of 3000 has an RPM of 22,200. You see that his is less abstract than the turn rating as lower KV numbers mean less RPM and (generally spoken) less power whereas lower turn ratings mean more power.
Death Star Delta
The turn rating get even more complicated when the so called "Delta" and "Star" winding comes into play. They totally change the characteristics of a motor and describe how the copper wires are connected to each other. This configuration makes it at least three terms (delta turns, star turns and KV rating) to know when "speaking motors". As a rule of thumb: Motors in Delta configuration give less torque at low RPM but higher overall RPM while Star configuration motors have more low-end torque with less overall RPM. D'oh!
The right pick
"Okey-dokey, what's my motor then", you might think? In below chart you find the most common can sizes, turn & KV ratings and applications. Simply pick the one(s) that suit your needs the best. Again, the information we give are just of a general type. They often differ a bit with the batteries you use as well as with many other parameters like track (conditions), the chassis type (shaft or belt drive, 2WD or 4WD etc.) but they are a general rule of thumb you can't go wrong with.
Now that you choose the correct motor can size and winding for your ride, the next question is: How do I gear it right? Gearing recommendations are a tough task as the depend on many factors like scale and type of the model car, voltage of the battery pack, the speed controller (and setting), the track, track conditions etc. With the gearing information in above chart we try to give you an idea of how to gear your RC-Car without harming motor, speedo or the drivetrain. Always monitor the motor's and controller's temperature and make sure they do not exceed 90°C!
Therefore, if you try to figure out the correct gearing for your motor, run the car for two minutes and check motor and speedo temperature. If they are below 40°C, carry on. if they are above, choose a 2 teeth smaller pinion gear and start again. After four minutes, temperatures should not exceed 60°C. If so: try a 2 teeth smaller pinion. If the motor and controller temperature is above 90°C after you finished your run: Let the components cool down to ambient temperature, try a 2 teeth smaller pinion and have go again. Adjust the temperature of the motor and speedo until you reach a temperature of or below 80°C (the cooler the better especially when it comes to the speedo!) and you are on the safe site without sacrificing performance.
Now you should know virtually everything about picking the right motor size, type and gearing to suit your needs.
Pick the right brushless motor
Whether you are new to electric RC-Cars, been long out of the hobby and now come back again or you normally race nitro cars and want to take a breath of fresh air during the winter by using electric power, you may be faced by something that is called an Electric Brushless Motor.
As usual we do not bore you with technical or physical terms, mathematic formulas and what not (well, maybe a bit later ...). Those of you who want to dig a bit deeper find all information about how an electric brushless motor (and controller) works here.
280 or 700?
We promised you not to go into deep in terms of "how brushless motors work" but we have to tell you a bit about the different types and sizes. Normally all (RC-Car) electric motors follow some basic rules when it comes to can sizes. Many, many moons ago the japanese company Mabuchi invented the "RS" called line of brushed electric motors for cars, boats and airplanes. The RS 380 and RS 540 are a, if not THE, synonym for basic electric motors and are still used in many basic RC-Car models from Tamiya, Kyosho and many others. The numbers described the can sizes of the motors and these are still in use with todays modern electric brushless motors. Here's a rundown on the most popular can sizes:
The 540-size motors are the most common with RC-Cars as they are used for the 1/10 scale competition classes and therefore you may find the largest variety of different motors in this can size. This class of motors also is one of the very few where the so called "Turn" rating is still in use. "Turn" describes how often the copper wire that is used inside the motor, is wounded around the rotor poles (Again we have to refer to the above Wikipedia article for those who don't know who an electric motor works). For the impatient ones of you: The less turns, the more power is generated by the motor. Or even more simple: a 4.5 turn motor is faster than a 21.5 turn motor.
Death Star Delta
The turn rating get even more complicated when the so called "Delta" and "Star" winding comes into play. They totally change the characteristics of a motor and describe how the copper wires are connected to each other. This configuration makes it at least three terms (delta turns, star turns and KV rating) to know when "speaking motors". As a rule of thumb: Motors in Delta configuration give less torque at low RPM but higher overall RPM while Star configuration motors have more low-end torque with less overall RPM. D'oh!
The right pick
"Okey-dokey, what's my motor then", you might think? In below chart you find the most common can sizes, turn & KV ratings and applications. Simply pick the one(s) that suit your needs the best. Again, the information we give are just of a general type. They often differ a bit with the batteries you use as well as with many other parameters like track (conditions), the chassis type (shaft or belt drive, 2WD or 4WD etc.) but they are a general rule of thumb you can't go wrong with.
Therefore, if you try to figure out the correct gearing for your motor, run the car for two minutes and check motor and speedo temperature. If they are below 40°C, carry on. if they are above, choose a 2 teeth smaller pinion gear and start again. After four minutes, temperatures should not exceed 60°C. If so: try a 2 teeth smaller pinion. If the motor and controller temperature is above 90°C after you finished your run: Let the components cool down to ambient temperature, try a 2 teeth smaller pinion and have go again. Adjust the temperature of the motor and speedo until you reach a temperature of or below 80°C (the cooler the better especially when it comes to the speedo!) and you are on the safe site without sacrificing performance.
Gear what?
In case the manual of your car does not supply you with a gear ration chart, here's how to figure these important information out for yourself:
In case the manual of your car does not supply you with a gear ration chart, here's how to figure these important information out for yourself:
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