Level 3 — Power & Electronics
Energy, wiring, drivers, and electrical stability
Power is the robot’s bloodstream. Most real-world failures in robotics are not “code bugs” — they are power problems: voltage drops, unstable supplies, noise, overheating drivers, weak wiring, and missing protection.
This level explains how to build a power system that is stable, safe, and predictable.
Power architecture
A practical robot usually needs separate power domains:
- Motor power — high current, noisy
- Logic power — clean and stable (microcontroller, sensors)
- Optional auxiliary power — LEDs, communication modules, peripherals
The goal is simple: motors must not disturb logic.
Batteries
- Li-ion — stable, good energy density, safer for many builds
- Li-Po — high discharge capability, requires careful handling
- Capacity (mAh) defines runtime
- Discharge rating defines whether motors will be fed properly
Battery choice is not “bigger is better”. It is “correct current capability + correct voltage”.
Voltage regulation
Robots rarely run directly from battery voltage. They use regulators:
- Step-down (buck) — efficient, common for 5V/3.3V rails
- Linear (LDO) — clean output, but wastes power as heat
A regulator must be sized by current. Undersized regulators cause resets, sensor glitches, and random control failures.
Motor drivers
Motors must never be driven directly from microcontroller pins. Drivers handle current, switching, and protection.
- H-bridge — bidirectional DC motor control
- ESC — BLDC control
- Stepper driver — current-limited phase control
- Servo control — signal-level PWM, power still must be delivered correctly
Grounding and wiring
Wiring is part of the system. Thin wires and bad ground topology create voltage drops and noise.
- Use star grounding when possible
- Keep motor current loops short and separate
- Twist motor wires to reduce EMI
- Do not share weak ground paths between motors and sensors
Noise and protection
Motors generate electrical noise and voltage spikes. Protection is mandatory in real builds:
- Flyback diodes (where applicable) to suppress inductive spikes
- Capacitors near drivers and logic rails for stability
- Fuses or current limiting to prevent catastrophic failure
- Thermal management for drivers and regulators
Symptoms of power problems
- random microcontroller resets when motors start
- sensor readings jump during acceleration
- motors lose torque unexpectedly
- drivers overheat or shut down
- communication becomes unstable
Next: Level 4 — Sensors