Chief Delphi - 3 CIM Drive Train Battery Draw

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Re: 3 CIM Drive Train Battery Draw

Quote:

Originally Posted by robohead456 (Post 1340524)

We used 4 CIMs for driving the robot and another 4 to pull it up the pyramid.

No, you didn't. Not unless every inspector at your event was asleep the entire time. Double check with your team, and you'll find you used at least a couple of mini-CIMs.

Re: 3 CIM Drive Train Battery Draw

Quote:

Originally Posted by z4t143 (Post 1352153)

I'd like to add my thanks to Big Al and the FMS crew at CIL for their help!

One additional question for Al ... other than the weight penalty, is there any other consideration or FRC rule implication to moving to larger gauge wire on the Battery to PDB loop?

Section 4.8 of the game manual and related figures all reference 6 AWG Wire (min).

It may be easier for us to move to larger wire at this point versus re-arranging components. Thoughts?

There's no rule against using a larger wire size but the PD board will only take up to a certain size wire.

Re: 3 CIM Drive Train Battery Draw

You are very welcome, I wish I could have done more. The wire gauge tables actually double wire size and halve resistance for every jump of four gauges. That is to say that to halve the resistance, you could move from #6 to #2 wire. This is a small change in overall weight compared to the total robot weight. However, you can achieve the same result by halving the length of the #6. This is electrically better and less weight overall. For your robot, this is easily achieved by rotating the PD, and moving the battery and main breaker. It is easier than you think. As I suggested, move the cRio away from the middle of the side of the robot. Replace it with the main breaker which will remove two feet of #6. Rotating the PD (and changing the breaker positions) is very easy as well. The radio and cRio wiring will need to be replaced, which are two of the easiest to change. You can premake those before St. Louis. About the hardest thing to accomplish is the move of the battery. These three things will reduce the #6 length by more than 5 feet I would guess. Added to the removal of one CIM on each side and the addition of some omnis, I bet you get to a point where electrical brownout may be reduced to zero. As a rough guess, with the six CIM drive as you are now, I would expect that the #6 wiring is dropping 2-3 volts on a fresh battery. Added to the 5 volts dropped across the battery internal resistance at this current, that is very close to the dropout voltage for the PD power supplies, the DSC and the 2 CAN. Please let me know if that helps.

Re: 3 CIM Drive Train Battery Draw

Quote:

Originally Posted by Al Skierkiewicz (Post 1352359)

Thanks Al. We're already planning options of pre-wiring a new PD board in the flipped orientation so we can come in ready to flip it and re-position the electrical layout on Thursday at St. Louis. We'll report back with our results.