I’m looking to buy 4 of these motors robotshop.com/en/12v-5310-rp … motor.html could someone suggest a motor controller, either single or dual that can be controlled via usb via the serial device to give it commands.
That motor has a free running current of 2.7A and a stall current of 133A. The current at maximum efficiency is 19.8A and at maximum power is 67.9A. It’s therefore best to have a controller which can provide at least 75 to 80A continuously.
30A+ DC motor controllers can be found here (many accept serial input): robotshop.com/en/high-power- … llers.html
that doesn’t make sense… each motor is 28$ and according to what you wrote it would cost over 200$ per motor for each motor controller (probably more since I can’t find the amperage close to what you suggested but only less or a lot more)
Correct. Normal non-geared DC motors themselves are normally very inexpensive (the motor in a cordless drill can be ~$5) largely because they are produced in the tens or hundreds of thousands of units per production run. The CIM motor is the largest DC motor we carry and is $28 USD. In order to vary the voltage to a DC motor (which controls speed and direction), you need a DC motor controller which is able to handle the current. Large DC motors which operate at lower DC voltages (12V in this case) require very high current. High current motor controllers cost a lot more than low current controllers. Unfortunately motor controllers which are available outside of mass produced commercial products have significantly lower production runs which increase their price as well. Although we don’t have any motor controllers which are 70-90A, it’s best to choose one which can provide more rather than less current, as selecting one which can only provide 60A may create issues.
I called andymark and an employee suggested a 40A motor controller they sell for this particular motor which they also sell, someone is not telling me the truth
According to the document provided by the supplier, the continuous current draw at maximum efficiency is 19.8A and at maximum power is 67.9A. Although the stall current is 133A, you do not need to design for this.
robotshop.com/media/files/pd … m-0255.pdf
If you only plan to use light loads, you may draw close to 19.8A (or even below), though most customers who purchase this motor require it for the torque, and as such, intend on operating it closer to the maximum power setting. Therefore in most applications requiring such a large motor, the motor will draw between 19.8A and 67.9A continuously (40A falls within this range). When choosing a DC motor controller, you need to select based on what you consider to be your operating conditions; what torque your application needs, and what would be the maximum torque it might encounter, even momentarily. This will help you determine the current draw (momentary and continuous) from the motor controller. If you don’t think your application will require that the motor will never draw more than 40A, then you have made an informed decision. We tend to suggest a small margin of safety to prevent damage to a controller should the continuous current be higher than anticipated. Note that the link provided was to the 30A+ motor controller category. We would like you to be happy with your your purchase and make an informed decision.
Ok now we’re getting somewhere, after playing with the DC motor calculator tool on your website and looking at the DC motor controllers again, there’s one I have my eye on. How about if I purchased two of these robotshop.com/ca/en/usb-robo … oller.html (one for the left side of the wheels of the robot and on for the right side, 2 wheels on each controller). Its a 60A controller which is close to 69.7A from your previous post. The thing is the chassis and motor kit that come together for this robot claims to support a payload of 400lbs but I won’t be anywhere near that, I would cut that number by at least half (no more than 150-200lbs payload). What are your thoughts? Is this motor controller good to meet my needs? And another thing, why do some people say motors use stall torque when first started (in this case 133A) but you said its not required?
Perhaps we missed it, but can you specify which platform you are considering? 200 pounds is almost heavier than the largest robot we carry, so the CIM motor is correct, but do you have gearing?
The more information you can provide the better.
This is the platform robotshop.com/en/toughbox-na … assis.html , if you look at the specs below :
Estimated Chassis Weight: 23 lbs
Estimated Load Capacity: 400 lbs (based on wheels)
I said I would be needing only about half of the load capacity so again my question would be, would the roboclaw dual channel 60A controller be suitable for this chassis/motor combination?
robotshop.com/blog/en/drive- … -tool-9698
Inputting some values (weight of 200lbs, drive wheel radius = 8", 4 drive motors, assume max angle of 10 degrees etc), the torque required per motor is around 2000oz-in
The Tube gear box which is part of that frame provides a 12.75:1 gear ratio, meaning each motor will need to provide ~156oz-in (2000 / 12.75).
According to the torque - current curve for the CIM motor, this means a current of ~60A continuous per motor in this situation.
However, should the robot go up a steeper incline, if you add weight, lose efficiency etc, this value will increase.
Once again, this is all theory, but intended to give you a good starting point.
Therefore the Roboclaw Dual 60A motor controller would potentially be “cutting it close” for this setup.
You assumed an 8" wheel radius, I was planning on using 6" wheels so the radius would be 3", if I plug your numbers in and put 3" instead of 8" for the wheel radius I get a much lower torque required per motor (about 716 ozf-in). To me this seems the 60A motor controller would be more than enough or am I wrong?
My apologies about the radius assumption, but the idea was to communicate the procedure.
Now that you know the wheel radius, you are correct, the maximum torque (in that configuration, if it is indeed the maximum the robot will encounter), will be around 716oz-in, which corresponds to ~25-30A.
Therefore the RoboClaw becomes a much safer choice.
We do apologize for any confusion or assumptions, though it’s always best to provide as much information up front as possible 
We look forward to seeing your creation!
I’m sorry for not giving all the details up front as well, I’m just trying to save money during the build process by trying to understand each component of the system, as this is not my first robot build I do have some limited knowledge already.