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FRC ELECTRICAL

Current Budget & Brownout Checker

Add your mechanisms and motors, set your smart-current limits, and see whether your branch breakers, the 120 A main, and the roboRIO brownout line hold up when everything runs at once. Bus-voltage sag is a first-order estimate.

Figures: motor specs from the FIRST 2017 motor sheet & vendor pages; breaker / brownout data from WPILib (evergreen). Verify against the current FIRST Game Manual and vendor spec sheets.

System & battery

Sets the brownout line: 1.0 is fixed at 6.3 V; 2.0 defaults to 6.75 V.

roboRIO 2.0 is software-settable via setBrownoutVoltage().

Conservative default 12.5 V. Enter your measured resting voltage — a healthy match pack reads ~12.7–13.5 V open.

0.015

0.011 Ω mfr spec · <0.015 Ω ideal · >0.020 Ω retire (WPILib). Use your Battery Beak reading.

Mechanisms

A
A
A
A
160 A total · breaker tight
A
30 A total · breaker tight
A
A
80 A total · breaker tight

Simultaneous system draw

160A
vs 120 A main breaker40 A over
SafeEst. bus voltage 10.10 V (V₍oc₎ − I·R estimate)
Blackout 4.5Brownout 6.75Rail 6.8Recover 7.5
Drivetrain: each of the 4 motors (~40 A) is at its 40 A branch breaker limit — little headroom.
A Intake motor (30 A) is within 15% of its 30 A branch breaker — little headroom.
Elevator: each of the 2 motors (~40 A) is at its 40 A branch breaker limit — little headroom.
Simultaneous draw ≈ 160 A is past the 120 A main breaker — sustained overage will trip it (battery can source >180 A only briefly).

Per-motor breaker headroom

Each motor controller is on its own branch breaker, so headroom is checked per motor — not against the mechanism’s summed draw.

Drivetrain160 A total
Kraken X60 (Trapezoidal)
40/40 A
Kraken X60 (Trapezoidal)
40/40 A
Kraken X60 (Trapezoidal)
40/40 A
Kraken X60 (Trapezoidal)
40/40 A
Intake(idle)30 A total
REV NEO (V1.1)
30/30 A
Elevator(idle)80 A total
Falcon 500
40/40 A
Falcon 500
40/40 A
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