13-09-2006, 09:18
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I live for the details.
 FRC #3620 (Average Joes) Team Role: Engineer
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Join Date: Jan 2003
Rookie Year: 1996
Location: Southwestern Michigan
Posts: 3,647
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Re: Battery Testing
Quote:
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Originally Posted by Al Skierkiewicz
One thing to keep in mind at all times, the internal resistance of the battery is 11 milliohms, draw max current (400 amps) from the fully charged battery and the terminal voltage will drop to 7.5 volts. A robot that will draw high current throughout the match will cause that voltage to drop to perhaps as low as 4 volts later in the match when the battery is discharged. 4 volts=robot dead! Take that same battery out of the robot and measure with a DVM and it will read 12 volts, no load, but won't run another match.
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Emphasis added.
Thanks for jumping in here, Al. I think it bears repeating that simple voltmeter measurements do not indicate very much about a battery's readiness. Too many teams neglect battery management and suffer the consequences.
__________________
Richard Wallace
Mentor since 2011 for FRC 3620 Average Joes (St. Joseph, Michigan)
Mentor 2002-10 for FRC 931 Perpetual Chaos (St. Louis, Missouri)
 since 2003
I believe in intuition and inspiration. Imagination is more important than knowledge. For knowledge is limited, whereas imagination embraces the entire world, stimulating progress, giving birth to evolution. It is, strictly speaking, a real factor in scientific research.
(Cosmic Religion : With Other Opinions and Aphorisms (1931) by Albert Einstein, p. 97)
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