powermon

macOS power draw and battery monitoring CLI tool. Samples CPU, GPU, and ANE power every second, stores data in SQLite, and visualizes live and historical usage in the terminal.

Features

• Live monitoring with real-time sparkline visualization
• Per-component breakdown: CPU, GPU, and ANE (Neural Engine) power
• Charging split: Estimates power going to system vs battery charging
• Historical views: Hourly and daily aggregated charts
• Battery tracking: Charging state, percentage, and power source (AC/Battery)
• Adapter info: Detects connected charger wattage
• SQLite storage: All data persisted to ~/.powermon/data/powermon.db
• Zero dependencies: Uses macOS CLI tools only (powermetrics, pmset, system_profiler, sqlite3)

Installation

# Clone and build
git clone <repo>
cd powermon
go build -o ~/bin/powermon ./cmd/powermon/

# Add to PATH (if not already in ~/.zshrc)
echo 'export PATH="$HOME/bin:$PATH"' >> ~/.zshrc
source ~/.zshrc

Usage

Power metrics (requires sudo)

powermetrics needs root privileges to read CPU power data. Set up passwordless sudo:

echo "$USER ALL=(root) NOPASSWD: /usr/bin/powermetrics" | sudo tee /etc/sudoers.d/powermon

Commands

# Live monitoring (Ctrl+C to stop)
sudo powermon live
sudo powermon live -interval 2s    # Sample every 2 seconds

# Snapshot views
powermon status                     # Current power/battery status
powermon view                       # Recent readings with sparkline
powermon sparkline                  # Sparkline of recent power draw
powermon today                      # Today's power statistics
powermon dump -n 50                 # Dump raw readings to terminal

# Historical views
powermon hourly -days 14            # Hourly aggregated bar chart
powermon daily -weeks 8             # Daily aggregated bar chart

Output Examples

Status:

Power: 4.5 W
  CPU: 4.5 W  GPU: 0.0 W  ANE: 0.0 W
Battery: 50%
Source: AC
Status: ⚡ Charging
Adapter: 60 W

Live view:

⚡  Total: 8.5 W
         System: 6.5 W  Battery: 2.0 W
         CPU: 5.0 W  GPU: 1.5 W  ANE: 0.0 W
         Adapter: 60 W
  Battery: 51%  Source: AC
  Time: 14:05:00

  Power (W)
  ▁▂▃▅▆▇█▇▅▃▁
  ------------------------------------------------------------
  Min: 3.2  Avg: 5.8  Max: 12.3 W
  15 samples

Dump:

TIME                      WATTS     BAT%    CHG      SYS    CHG W   BATT W SOURCE
--------------------------------------------------------------------------------
2026-04-20 14:00:00        5.2      50% ⚡     5.2 W     0.0 W     5.2 W AC
2026-04-20 14:05:00        8.5      51% ⚡     6.5 W     2.0 W     6.5 W AC
2026-04-20 14:10:00       12.3      52% ⚡     8.3 W     4.0 W     8.3 W AC

How It Works

Power measurement

• System power (CPU + GPU + ANE): Read from powermetrics --samplers cpu_power
• Battery charging power: Estimated from battery % change rate × battery capacity
• Adapter wattage: Read from system_profiler SPPowerDataType

Charging split

When the battery is charging, the tool estimates how much power goes to the system vs. charging the battery:

Charging power = (pct_change / 100) × battery_capacity_Wh / time_hours
System power = total_power - charging_power

The split updates whenever the battery % changes (typically every ~30 seconds during charging).

Data storage

All readings are stored in SQLite at ~/.powermon/data/powermon.db:

Column	Description
timestamp	Sample time
power_draw	Total CPU + GPU + ANE power (W)
cpu_watts	CPU power (W)
gpu_watts	GPU power (W)
ank_watts	ANE (Neural Engine) power (W)
charging_watts	Power going to battery charging (W)
system_watts	Power going to system (W)
is_charging	Battery charging state (bool)
battery_pct	Battery percentage
source	AC or Battery
adapter_w	Charger rated wattage

Architecture

cmd/powermon/   CLI entry point with all commands
pkg/power/      macOS power data collection (powermetrics, pmset, system_profiler)
pkg/db/         SQLite storage layer via sqlite3 CLI
pkg/vis/        Terminal visualization (sparklines, bar charts)

Requirements

• macOS (tested on Apple Silicon)
• Go 1.22+
• sqlite3 CLI (pre-installed on macOS)
• Root privileges for full power metrics (powermetrics)

License

MIT