Cim motor newbie

So I purchased a cim motor because it is perfect for a personal project I am working on, but I did not think it through and have no idea how I will power it… what is the cheapest way to get a cim motor to spin… fast-ish. I don’t need to control the speed or reverse it, just need it to spin and I will use a relay for the rest.

Plug it in to a battery


Wired directly to a 12 volt battery it will spin approximately 5,000 RPM I believe


What attributes make the CIM motor perfect for your personal project?


Under the assumption a standard FRC battery isn’t an option for some reason…

The magic words to be googling are “12V XA power supply”. But, replace X with some number based on how much current you think the motor will be drawing, and how much you’re willing to spend (bigger X = bigger $$$).

If you’re just running the motor without anything attached to the output shaft, you’ll probably be able to get by with something in the 25A - 50A range.
This one, for example.

If you’re putting big loads on it, you’ll need something closer to 100A-200A… which is gonna get really pricey really fast.

IE, battery might just be better.

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As someone who has (rather questionably) used a CIM for oddball purposes before, including a “run flat out when I want you to and I don’t care about the direction”…

Yes, you want a relay. This one works (at least in said oddball application). But you also need a 12V power supply. @gerthworm posted one example; I prefer a different brand but to each their own–unless you happen to have one already.

That said: What sort of project are we talking about, and what generally are you wanting the CIM to do (and, uh, rather importantly: at what speed/torque)?


Meanwell is probably better. That one’s pretty cheap.

A fellow connoisseur…

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I’ve used one before, and they are fast lol I also already purchased it because I didn’t think

thank you!!

thank you so much for bearing with my newbie-ness, this looks like it should work but I might just spring for the battery as I might want to use them in the future

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Cheapest way? Go to a old electronic recycling center and pull a power supply out of a old computer tower. Sometimes places will give it to you for free. Then you can solder all the 12v wires together to run the motor.
Disclaimer: While I have opened up power supplies, be careful modifying/opening a power supply as there is still power stored in capacitors which can shock you.

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This may not be enough current for you, but

this battery.

Also, I would not just recommend a relay, but a fuse off of the battery at least. Perhaps one of these

If you are using more than one motor, you can even get a pdp for cheap too (this one may not have enough current capacity for your needs but there are many simillar ones). Of course it is not as smart as the CTRE ones we use, but the price.

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I agree with this question

If your project is not all that power intensive, you may want to ask around to some of the teams in your area to see if any of them have old batteries. We replaced our batteries last year as they were too worn out to use in competition. We kept a few of the better ones for practice batteries. But we had several that we ended up just taking to a recycling center. You may find a team that is in a similar situation and that has an old battery that is no longer competition quality but that would be fine for your project.

Regarding the CIM motor itself, there are also teams around that have pretty much stopped using CIM motors on their bots and have switched to brushless motors. Since we all get CIM motors in the KOP every year, many teams have built up a stockpile of these motors that they will never use. We bring our stockpile to our regional kickoff event every year and just set it out with a sign that says “free” so that other teams in the region that want the motors can take them. But we never manage to give away all our motors. We still have 8-10 of them in a bin. We have donated a number of them over they years to non-FRC projects like motorized wheelchairs and science fair projects where they could be put to good use. If your project is interesting, I think you could have easily gotten the motor for free from a team in your area.

We have also unloaded a number of our old motor controllers like the original Spark controllers that we had laying in our inventory, but there are probably teams out there that still have these and have no intention of using them in the future that might be willing to donate them to your cause. You can drive the Spark with a servo controller like this one. Note - I have not used that particular model. We have a 4 channel servo controller from ServoCity that we use for prototyping that is more expensive. I was looking for a cheap option for you. You may be able to find something cheaper that will work for your project if you search a bit.

In the past, I’ve found a used server power supply with a 12v DC bus rated at 130+ amps on Ebay for <$100. The hard part was finding datasheets and not being picky.

If you want to save some coin and feel like doing a bit of programming, you can also drive a spark pretty easilly with an esp32 or arduino nano.

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