CIM Motor Capacitors

[ProgramLuke]

Originally Posted by RyanN

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.

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?

[DarrinMunter]

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.

[ProgramLuke]

Yes the Dlink is powered by the converter.

[billbo911]

Originally Posted by Munter2081

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.

Originally Posted by ProgramLuke

Yes the Dlink is powered by the converter.

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?

[ProgramLuke]

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!

[DarrinMunter]

Originally Posted by ProgramLuke

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!

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

[Al Skierkiewicz]

Originally Posted by Munter2081

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

Me?!?

[DarrinMunter]

Originally Posted by Al Skierkiewicz

Me?!?

It was Raul,
He said that he seen a couple of teams make the same mistake.
Blew us away, because everything was working on the test frame. When we moved everything over to Lunacy robot some how that got changed.

Lesson 1: Move over stuff one thing at a time.
Lesson 2: Take picutes before hand. Use them as a reference.
Lesson 3: Labels! What to where.


You can learn a lot from making mistakes - even more from fixing them.

[RyanN]

Originally Posted by ProgramLuke

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!

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
Page 6 of 10.

[caffel]

This is a great thread.

I'd like to add a note that 1712's and several others converters 12v - 5v for the Dlink, failed.

It failed by providing only 4.1 volts.
Once you have tried all of the above advice, try tracking the 5v in at the Dlink and make sure its OK all the time.

Dropouts are happening in other areas of the robots this year and they are hard to diagnose, so look at the threads on Jaguars and encoders next as well.

[caffel]

One thing I learned early on, in robotics what you get is what you don't see.

Use meters to reveal things.
Voltage is easy.
DC Current is thought to be hard, but check out the Kussmaul Electronics 091-8 strap on ammeter. (inductive ammeter)

If you are overloading the main or subcircuits, this will pinpoint the problem for less than $20 and without disconnecting any wires.

Snap-on Tools has similar meters, but they are pretty expensive.

[DarrinMunter]

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

[DarrinMunter]

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.

[ProgramLuke]

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.

[RyanN]

Originally Posted by ProgramLuke

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.

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.