Re: Motors: Past and Future
 

It can still support tons and tons of power. It has close to the capacity of a CIM even at 12v.

Re: Motors: Past and Future
 

Yeah, it's going to be pretty darn inefficient even if it were legal. You would have a real tough time finding a DC-DC converter that could boost from 8-13.5 V to 18 V with any respectable amount of current. You'd have to put several in parallel and you would have fun carrying that much current on a PCB. Even if you could find an adjustable boost converter capable of 5A, it would be at least $10/IC....and you'll need what? 8-10 of them?

Re: Motors: Past and Future
 

Rotary converter then rectify the output ;).

Re: Motors: Past and Future
 

$10 is waaaay too low an estimate. You want a 40 amp 12-18v converter. That will weigh several pounds and probably cost between $50 and $200 (I can't find one on ebay to get a closer estimate).
Making your own would just be a coupld $2 transistors rated for 60+ amps, a heatsink, and a large inductor. The inductor would be the hardest to source, as high-current high-inductance coils are expensive.
It wouldn't need to be adjustable as long as the motor controller can support the voltage, as you can place the controller after the boost converter.

Re: Motors: Past and Future
 

In some applications, this motor can actually deliver more output than a CIM. Motor performance decreases with increasing armature temperature, and in some operating conditions the CIM's armature temperature rises faster than the 775-18's. One example might be a continuously running intake.

Of course, a continuously running mechanism that is also likely to stall should be powered with a CIM rather than a 775-18.

Re: Motors: Past and Future
 

Ok
So I have read every word in the Motor section, power distribution and command and control, command & signals system from last years rules and NO where does it expressly prohibit an 18vdc motor being ran by 18vdc.

If someone can find any differently I would be surprised.

Here is the caveat that I feel would allow it.

4.8.10 R40
Any active electrical item not explicitly listed in R29 or R67 is considered a CUSTOM CIRCUIT. CUSTOM CIRCUITS
may not produce voltages exceeding 24V when referenced to the negative terminal of the battery.

Since R29 references the motors it does not apply to custom circuits. Also the speed controllers are rated up to 30vdc so they can handle 18vdc

Whether or not this is feasible/recommendable etc etc is a different question.

I am only after the legality of the question right now.

Re: Motors: Past and Future
 

Usual caveats about how rules can always change...

Re: Motors: Past and Future
 

Al already answered that. R53 bars custom circuits from altering power pathways between the PD board, speed controllers, and motors.

And yes, this booster IS a custom circuit. R29 is the motor list. R67 covers the Jaguar/control system interface. A voltage booster is not listed in either. You can also reference the definition of Custom Circuit--no voltage booster listed, therefore, it's a custom circuit. Because it's a custom circuit, it cannot alter the power pathways. I would consider boosting the voltage, either before or after the speed controller, to be an alteration of the power pathway, and thus illegal.

Re: Motors: Past and Future
 

Basically, unless a CUSTOM CIRCUIT is also a non-functional decoration, it can only be an input*.

*Under the 2014 rules.

Re: Motors: Past and Future
 

Hopefully things will change in 2015. Seems a shame to have the ability for an 18vdc motor and not use it to its full potential:(

Thanks for all of your help.

Cheers :D

Re: Motors: Past and Future
 

Going to 18V batteries for FRC seems like a good way to double the kinetic energy each robot could potentially bring to a collision. While there are quite a few teams already practicing robust design, the majority of FRC robots I inspected in 2014 would not be robust enough if they simply had 18V "dropped in" to replace the 12V batteries around which they were designed.

Back in 1996 we used to play with 12V drill batteries, two to a 'bot IIRC. The step up to the 12V sealed lead acid UPS/scooter batteries came a few years later. The average FRC robot today is much more powerful, and much more robust, compared with those early years.

Is the FRC ready for another step up in electrical storage?

Re: Motors: Past and Future
 

With 30 motors available*, I think they need a step up in electrical storage (and current capacity of the main breaker).

Get a battery company to donate enough 12V 25~30Ah LiFePO4 batteries for every team to have at least 4 and I don't think FIRST will have any choice but to change batteries**.

*2013 & 2014 rules.

**This applies to any electronic component you want to use. If enough is donated, the GDC will make it legal.

Re: Motors: Past and Future
 

I don't know why it's so important that we run the 18v motor at 18v. Even at 12v it's a very powerful, useful motor. We're not exactly wasting its potential - anything would be more powerful at a higher voltage...

Re: Motors: Past and Future
 

I don't think that's wise. Just because we have motors doesn't mean we have to use them. It's just nice that we have an array to choose from.
All that adding more motors will do increase the energy available to each bot, causing more damage and collisions and safety concerns. As it stands, we have enough motors to drive about as fast as a driver can handle. Main breaker blows are the exchange for that kind of speed. Making it bigger would make drivers drive more dangerously.

Re: Motors: Past and Future
 

to get the increased power associated with a higher-than-spec voltage, the motor must operate at a higher-than-spec speed.

the motor must be designed to operate at the higher voltage and speed.

the RS-775-18 is designed to operate at 18 volts, and the speeds associated with that higher voltage.

can the same be said for the 12V FRC motors? who knows.