Are Capacitors Legal?

[mechanicalbrain]

FIRST Q&A is down so I wanted to double check this. Capacitors are in fact illegal right? Are they considered an alternate power source?

[ahecht]

I can't speak for the 2006 rules, but in the 2005 rules, as far as I can tell, capacitors are legal if they are not used as a power source (i.e. they follow all the rules pertaining to custom circuits). You should be fine using them in an RC filter circuit in custom electronics.

[mechanicalbrain]

Great I have a 54 Farad capacitor bank I wanted to use and I didn't want to go buy a couple and have it be illegal. I think on second thought though ill wait until kickoff to see what Dave Lavery pull out of his sleeve this year. I'm looking forward to it.

[ahecht]

Originally Posted by mechanicalbrain

Great I have a 54 Farad capacitor bank I wanted to use and I didn't want to go buy a couple and have it be illegal. I think on second thought though ill wait until kickoff to see what Dave Lavery pull out of his sleeve this year. I'm looking forward to it.

As per the custom circuit rules, you could use that capacitor bank, but you could never use that stored power on any sort of output device. In fact, the output has to be connected to the analog inputs, digital I/O, TTL Serial Port, or Program Port. So, if you want to use your bank to fry your RC, nothing is stopping you (well, except for the hazardous devices rules).

EDIT: A 54 farad bank would probably violate the cost limits as well.

[Rickertsen2]

I assume you mean using a capacitor just like you would in a car stereo install. This usage is in fact illegal.

54 farad capacitor!!!!! Thats just scary.

[mechanicalbrain]

Ok, then ill use then in one of my own robotics projects as a battery replacement. Yeah they are 1.1 pound 54 farad capacitor banks with auto balancing software. They are a brand of ultracapacitors made by maxwell. http://www.maxwell.com/ultracapacito...s/modules.html

[Tristan Lall]

To add insult to injury, you would have to start the match with the capacitor discharged, per <R02>.

[sciguy125]

What are those things supposed to be used for!? What could you possibly do with a 430F cap at only 16V? They also have a 2.6kF for 2.5V. I couldn't find any price info though.

[Al Skierkiewicz]

Capacitors are not strictly illegal but they cannot be used for power filtering at the power input to the RC. As an inspector I would also need to see a valid method for discharging the capacitors at the end of the match. Something automatic and absolutely fool proof. Barring that, everything must be insulated.
Remember there is a lot of power locked up in a 54 Farad capacitor. Certainly enough to weld metal if it were to come in contact with something.

[mechanicalbrain]

I wanted to use it in conjunction with a CIM (before the speed controller). I couldn't find a rule that would flag it (I'm not sure the alternate power source rule would apply) but it would probably get flagged anyway. Yeah I know that 54 Farads is a lot but consider the power draw on a single CIM. These in particular are used as replacements for batteries. I might use it in an off season project to see what effect they have on the motors.

[Dave Flowerday]

Originally Posted by mechanicalbrain

I wanted to use it in conjunction with a CIM (before the speed controller). I couldn't find a rule that would flag it (I'm not sure the alternate power source rule would apply) but it would probably get flagged anyway.

A capacitor would be considered a custom circuit, subject to the custom electronics rules. Right off the bat, it would be in violation of these two rules from 2005:

Originally Posted by 2005 Manual, R51

All outputs from the custom circuits must be connected to the analog inputs, digital I/O, TTL Serial Port, or Program Port on the Robot Controller.

Originally Posted by 2005 Manual, R53

Custom Circuits may not: Directly affect any output devices on the robot, such as by providing power directly to a motor, supplying a PWM signal to a speed controller or supplying a control signal to a relay module. (Custom high impedance voltage monitoring or low impedance current monitoring circuitry connected to the robot’s electrical system is acceptable, because the effect on the robot outputs should be inconsequential.)

[Al Skierkiewicz]

Yeah, what Dave said! (Thanks Dave)
In that application it would be more of hindurance than you think.
That calculates out to 3888 Joules and by my guess would take almost 16 seconds to charge up during which it will look like a dead short across the battery for most of that. I calculate 240 amps will flow into the capacitor at the begninning of the charge cycle.

[mechanicalbrain]

Originally Posted by Dave Flowerday

A capacitor would be considered a custom circuit, subject to the custom electronics rules. Right off the bat, it would be in violation of these two rules from 2005:

Yeah your right it violates the first one but the second one? It is not providing power directly to the motor but through the victor. But the point is mute since it violates the first rule. Oh well this is starting to look better suited for a private robot. Just another idea I had been throwing around. Oh Mr. Skierkiewicz could I possibly power the capacitors seperately and then apply power to motors? Maybe with a second connection and a switch to apply a physical connection (A switch would also allow my to disengage the capacitors from the motor if needed)?

[KenWittlief]

what is the price and weight of one of those units, and what exactly do you expect it to do for you on the robot?

The batteries supplied in the kit are able to put out 200 to 300 amp surges - I think if you pumped any more current through a Victor or through the motor you would see a cloud of smoke where your robot use to be!

What problem are you attempting to solve by adding these to the bot?

[Kyle Fenton]

I would also think that it would be a safety issue. If someone touched that capacitor at the terminals it could seriously injure them. Also I don't think capacitors that big can handle that much vibration, which would make them impractical to use.