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Unread 13-05-2014, 17:56
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Re: 2-Speed vs 1-Speed drivetrain

Quote:
Originally Posted by Oblarg View Post
This is false.

This year we were having problems tripping our main breaker, and did a fair number of tests pushing against a wall. With a not-quite-full battery and the compressor running (i.e. pretty reasonable in-match conditions), we were only drawing ~50 amps per motor on a 6CIM drive when stalled.
Interesting. I will have to have the kids run some tests like this when we get the chance.

Quote:
Originally Posted by AlecS View Post
The voltage the battery outputs is proportional to the amperage being drawn, and the resistance of the circuit. This is also known as ohm's law.

V=IR

Although batteries are not always perfect voltage sources, you can use ohm's law to determine the voltage drop in your robot fairly accurately. If you were drawing 300 amps, and the total circuit resistance was .020 ohms, you would lose 6 volts. This does not fluctuate over time, it is directly related to the current being drawn. (ignoring temperature and other factors). Hopefully this clears things up.
This makes perfect sense. As we were talking about the drive train and gearboxes, I had forgotten about the electrical system itself, and was (incorrectly) assuming negligible resistance.