What is the FRC Robot Controller Power Consumption

[amateurrobotguy]

I need to know what the minimum rc power consumption is in amps (not amp hours) Specifically I need to know how many amps are required by the 12 V main power input for the board to function. I ask this because I want to use a non-robot battery to power it.

[BrianBSL]

We would need to know way more about your specific application to give you an accurate number.

I've never actually measured it - but based on my knowledge of what is inside it, I would say 20-70mA or so is a good guess - excluding the radio, anything connected to the 5v lines, and anything teatherd to it.

Remember that any current you draw from the 5V line will cause a pretty much equal current increase on the 12V line, since I'm pretty sure it runs off a linear regulator.

Even a 1Ah Nicad AA pack should be able to run it for a good amount of time if that was all you were running. If you have it controlling any motors it's current draw is going to be negligible.

[Al Skierkiewicz]

Originally Posted by amateurrobotguy

I need to know what the minimum rc power consumption is in amps (not amp hours) Specifically I need to know how many amps are required by the 12 V main power input for the board to function. I ask this because I want to use a non-robot battery to power it.

I would expect to plan for 200 ma to power the RC. This should cover most applications including team LEDs and all I/O that you might have. This is a dynamic (changing) load so design for the high side of current demand. Don't forget that the power used to feed the servo/PWM output is derived from the backup battery.

[dlavery]

It depends. If you are trying to run just the RC, then a 200mA supply as Al mentioned by Al should do fine. However, if you are also planning to use the competition radios to communicate to/from the RC, then you will need a 1500mA supply, minimum.

I haven't had a chance to actually measure the current pulled by the RC or OI (or the portion of that contributed by the radios). But I know that when we tried to use a 1 Amp supply (over the years, we have lost several of our OI and RC power supplies, so we now have a lot of experience with replacements), the RC appeared to work just fine. However, the performance and range of the eWave radio modem became questionable if we were more than 10 feet away. The RC will light up, and everything will look like it should be working, but you can't get any signal to/from the OI. Moving up to a 1200 mA supply extended the range to about 15 feet, but we still had lots of drop-outs. Somewhere between there and 1500 mA you cross a threshold, and at 1500 mA it works just fine.

Note that this is also true on the OI side of things - plan on at least a 1500mA supply.

-dave

[Al Skierkiewicz]

I meant to reply to this earlier. The RC manual lists power at 1.5 amps (that 1500 ma for you guys that thought Dave was fooling) and I should have known that since the 7805 (the internal three terminal regulator in the RC) is specified at 1.5 amps max. BTW, I had to search for it, the specs are not easily found. I have not yet found the electrical specs for the OI in any doc. Perhaps an IFI guy who knows will post up.