CIM Motor Capacitors
 

Where is a good place to buy capacitors for the DC CIM Motors allowed under:

Re: CIM Motor Capacitors
 

Locally? A Radio Shack. You may be able to find another electronic component store near you as well.

Online? Mouser, Digikey.

May I ask why you're doing this. Nothing wrong with it, but I'm just curious if you're having problems with the cRIO or the Dlink bridge cutting out.

Re: CIM Motor Capacitors
 

Luke,
I know that many teams do not think of moving the motor controller closer to the motor it controls but this is a good way to reduce motor noise and allow the motor to be connected directly to the controller without having to add wire to the motor. The CIM motor has not been known as a noise producer as compared to the FP for instance.

Re: CIM Motor Capacitors
 

We are indeed having issues with communications. We are using all 4 CIMS on our drivetrain but if we don't have a battery that idles around 13V We lose comms if we try to accelerate quickly. What happens is that the Dlink drops out and we have to wait for it to restart to get communications. Are other teams having issues like this and do you have any solutions?

Re: CIM Motor Capacitors
 

Do you have the power converter (12v in, 5v out) connected to the 12v output at the bottom of the PD board? And then the 5v from the converter feeds the radio.

Re: CIM Motor Capacitors
 

Yes the Dlink is powered by the converter.

Re: CIM Motor Capacitors
 

I found a PDF that shows how and where the converter gets connected.

Re: CIM Motor Capacitors
 

Can you block up your robot so you can run the motor and keep the robot in place?
You might want to take a voltage measument from the 12v coming from the PD board. If its going below 12V you have a problem with the PD.
That output has a special built in power supply that keeps the voltage steady at 12v - no matter what the battery is running at. ~ unless the battery drops way low, 7-8 volts.

Re: CIM Motor Capacitors
 

Luke,
Darrin's specific question included "Do you have the power converter (12v in, 5v out) connected to the 12v output at the bottom of the PD board?" for a very good reason.
If it is connected there, the regulator in the PDB will provide +12vdc even when the battery voltage dips below +12vdc. If the converter is not connected there, but is connected to the standard Wago connections, you will loose the +5vdc out of the converter when the voltage dips.

So, do you have the power converter (12v in, 5v out) connected to the 12v output at the bottom of the PD board?

Re: CIM Motor Capacitors
 

That's one of the issues. Unless the battery is absolutely fully charged and reading 13v+ we will get a drop to 8v or less. At that point we get loss of communication. We just did a run reading 12.8 volts and it immediately dropped to 8v- and lost communication.

Re: CIM Motor Capacitors
 

Thanks for the guidance. We had it coming out of the PD through a regular circuit. We will get that changed right away and see if it makes a difference. Really hoping this is the issue.

Thanks again!

Re: CIM Motor Capacitors
 

You're dropping too much. I'd look at the main power path from the battery all the way to the Power Distribution board. Bad crimps, looks nuts, nicked wire, undersized wire. You have too much resistance somewhere, or else some bad batteries.

A clue would be to feel all the wires from the battery terminals to the PD board. If any are warm, then there's your issue.

Also, 6AWG wire is a tiny bit small for the loads you might be putting on it. If you're running more than 2 feet of battery cable, I'd recommend bumping it up to 4AWG.

Also check for mechanical issues. Can you rotate your wheels pretty easily? Are they tough to spin? If they're tough, you might be binding too much and pulling too much current.

Re: CIM Motor Capacitors
 

Bad battery? We've had to get rid of about 2 of ours this year, because of that.
If your using a good battery, then you have excess load somewhere.
Run your motors one at a time and measure the battery voltage, the motor with the largest battery voltage drop is your problem. It could be the motor itself, or a speed controller going bad.

Re: CIM Motor Capacitors
 

We did the same thing two years ago! We were at the BMR, when a mentor from WildStang help us out.

Re: CIM Motor Capacitors
 

Yep, that's the main issue. The 12V coming out of the bottom of the PD board is a boost circuit. It is supposed to operate down to a battery voltage of 4.5V.

http://usfirst.org/uploadedFiles/Rob...tion_Board.pdf
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