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Unread 02-03-2014, 23:54
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Ryan Dognaux Ryan Dognaux is offline
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Re: 3 CIM Drive Train Battery Draw

Quote:
Originally Posted by Al Skierkiewicz View Post
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.
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.
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