hi guys. this is my first post on the forums. i have recently joined a team, was put into the electrical section, and was tasked with creating a power budget. i think i have gotten most of it down, but was curious, (plus i needed the information) what kind of wifi bridge/ connection device do you guys put on your robots.
The rules for the last couple of years have required the same bridge type: a D-Link DAP-1522, Rev. B. (Reference the Manual, Section 4.9.2, R55–ask a veteran teammate about that.) It’s that white box with a black band on your last year’s robot (or in your parts storage if you’ve already taken that robot apart–you REALLY want to keep the control system!)
That said, there is a possibility of a change, given that we’re getting a new control system this year.
The primary electrical constraint for power budgeting will be battery capacity. Our typical battery data sheet indicates about 6 Ah, or roughly 6 minutes of capacity when operating a bit above its 3C discharge rate (3 x 18 = 54 Ampere). So if your robot consumes 60 Ampere average current it will drain a battery in six minutes. Let aggressive students drive your robot around (on carpet) while operating pick-up devices, launchers, etc. in a manner similar to match conditions, and see for yourself how long a battery really lasts. My team has found the six minute figure fairly close, but we base our budget on less.
Also consider how long it takes to charge a battery, at the FRC 6 Ampere charging limit. Ideally, one hour to put back what you can take out in the six minute example above. Count on real recharging times to be longer than that, probably at least twice as long. Again, get real data – don’t rely on ideal assumptions.
Use the figures you get from the activities above to create a plan for managing a fleet of batteries that will get you through a competition, and through the season.