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Unread 15-12-2015, 17:40
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Mark McLeod Mark McLeod is offline
Just Itinerant
AKA: Hey dad...Father...MARK
FRC #0358 (Robotic Eagles)
Team Role: Engineer
 
Join Date: Mar 2003
Rookie Year: 2002
Location: Hauppauge, Long Island, NY
Posts: 8,817
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Re: SD540 Motor Controller

Quote:
Originally Posted by geezloueez View Post
I am a first year mentor for a rookie team. May seem like a dumb question, but I have not been involved first hand in a match yet. What is causing the batteries to drop so low? Are you using old batteries?
Here are a couple of real life examples to give you an idea of what you have to be prepared to manage in your power design.
Both Driver Station logs are from different teams that borrowed one of my laptops during competition.
Learn how to examine your own DS logs after a match. They are automatic and just brimming with useful data about how your robot performed.
Remember, too, that the power drawn during practice at home is tame compared to power drawn during a real match with competitors.

The yellow line shows the battery voltage for the duration of the match.
No roboRIO brownouts were experienced by either team during these logged events.

Both of these robots had good batteries.
These voltages are what the roboRIO and speed controllers directly experienced.
The first example is from a robot during an off-season event this past October with a large number of motors - drive, lift, tote grabbers all running.

The second example is also from an off-season event, but one held in November. It was a robot with four drive motors and one lift motor, and shows a lot less stress.

The biggest dips are when the motors are starting up from a complete stop, lifting a heavy load, or suddenly reversing.
These logs are taken from a game without active opposition. Expect much worse this coming season.
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Last edited by Mark McLeod : 15-12-2015 at 18:55.
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