Follow the Power from Battery to Load

An FRC robot is a mobile electrical system with a lot of current moving through a small machine.

The useful mental model is a power tree. Energy starts at the battery, passes through protection and distribution, then reaches branch devices and loads.

The main path

At a high level:

Concept flow

FRC robot power follows a protected tree

Current starts at the battery, crosses the main protection boundary, branches through distribution, and reaches controllers and loads. Diagnose shared failures by walking that tree with evidence.

1. BATTERYsource of robot energy
   through
2. MAIN BREAKERprimary disconnect and protection
   feeds
3. DISTRIBUTIONroutes power to branches
   protect
4. BRANCHbreaker/fuse and wiring for one path
   supplies
5. CONTROLLERregulates power to the load
   drives
6. LOADmotor, radio, roboRIO, sensor, or mechanism

The current season manual is always the authority for legal wiring, allowed devices, protection, and inspection details. This course teaches the architecture so the manual makes sense when you read it.

Voltage is not enough

A battery can show reasonable voltage with little load and still perform poorly when the robot demands high current.

Connections also matter. Resistance at a loose, damaged, or undersized connection can create voltage drop and heat.

That means an electrical diagnosis should ask what the system does under load, not only what a multimeter says while the robot is sitting still.

Branch protection has a job

Circuit protection limits what a branch can safely carry and helps isolate faults.

Do not treat breaker ratings as performance settings to increase until a problem disappears. If a branch repeatedly trips or a device browns out, find the reason.

The root cause may be mechanical load, wiring resistance, motor behavior, configuration, or an actual fault.

Case: robot resets during acceleration

Observation:

The robot behaves normally at low output but control becomes unstable during aggressive acceleration.

Possible evidence to inspect:

• battery condition;
• voltage sag under load;
• main power connections;
• branch wiring;
• drivetrain current;
• mechanical binding;
• software acceleration demand.

Notice how electrical and mechanical evidence meet. High current may be the symptom of a drivetrain problem, not only an electrical problem.

Concept flow

A shared power problem can look like many unrelated failures

When several systems fail together, inspect common dependencies before blaming whichever symptom appeared first.

1. OBSERVATIONrobot resets or multiple devices drop out
   inspect
2. BATTERY UNDER LOADvoltage sag and current demand
   then
3. MAIN CONNECTIONSloose, damaged, hot, or high-resistance path
   then
4. BRANCH EVIDENCEbreaker trips, controller faults, radio dropout
   compare
5. ROOT CLAIMdefend what the evidence proves and what it does not

Draw your power tree

Create a diagram for a typical FRC robot or your team robot.

Include:

• battery;
• main disconnect/breaker;
• power distribution;
• roboRIO/controller power;
• network/radio power;
• at least four branch loads;
• one motor controller/motor pair; and
• one location where a poor connection could affect multiple systems.

Next to each branch, write one observable clue that would tell you whether power is healthy.

Safety boundary

Do not perform live rewiring for this activity.

If hardware is available, trace with the robot safely de-energized. Restore power only for a controlled measurement or test under the rules and supervision of your team/shop.

Failure mode: “everything is a software problem”

When several unrelated systems fail at the same moment, look for shared dependencies.

Power is one of the biggest shared dependencies on a robot.

That does not prove power is the cause. It tells you power deserves a place near the top of the evidence list.