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StorageSecurity/Particle/docs/power-analysis.md

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Particle Boron LTE Power Analysis

Comprehensive power consumption analysis and battery life calculations for ultra-low-power security device operation.

🔋 Executive Summary

Configuration Daily Consumption Battery Life (5000mAh) Battery Life (10000mAh)
Typical Operation 3-5 mAh 2.7-4.6 years 5.5-9.1 years
Heavy Breach Activity 8-12 mAh 1.1-1.8 years 2.3-3.6 years
With Solar (6W) Net positive Indefinite Indefinite

⚡ Power Consumption Breakdown

1. Sleep Mode (STOP) - 99% of Operation Time

Current Draw: 130-150 μA (microamps)
Duration: 23 hours, 59 minutes per day
Daily Consumption: 130μA × 23.98h = 3.12 mAh
Percentage of Total: ~95% of daily power budget

STOP Mode Details:

  • Boron Core: 80-100 μA (CPU suspended, RAM retained)
  • Cellular Radio: OFF (completely powered down)
  • GPIO Pins: 10-20 μA (minimal leakage current)
  • Real-Time Clock: 30-40 μA (wake timer active)
  • Power Management: 10-20 μA (voltage regulation)

2. Wake and Process - Brief Active Periods

Current Draw: 80-120 mA (during processing)
Duration: 10-15 seconds per event
Frequency: 1-2 times per day (typical)
Daily Consumption: 100mA × 30s ÷ 3600s/h = 0.83 mAh

Active Processing Includes:

  • CPU Wake: Immediate response to pin interrupt
  • Sensor Reading: Check microswitch state
  • Decision Logic: Determine wake reason and response
  • Alarm Control: GPIO output to drive alarm circuit
  • Memory Access: Read/write retained variables

3. Cellular Connection - Network Communication

Current Draw: 300-800 mA (variable by signal strength)
Duration: 30-90 seconds per connection
Frequency: 1-3 times per day
Daily Consumption: 500mA × 90s ÷ 3600s/h = 12.5 mAh (worst case)

Cellular Power Phases:

  • Radio Startup: 200-300 mA for 5-10 seconds
  • Network Search: 400-600 mA for 10-30 seconds
  • Registration: 300-500 mA for 5-15 seconds
  • Data Transfer: 200-400 mA for 5-10 seconds
  • Radio Shutdown: 100-200 mA for 2-5 seconds

Signal Strength Impact:

  • Strong Signal (-50 to -70 dBm): 300-500 mA average
  • Moderate Signal (-70 to -85 dBm): 400-600 mA average
  • Weak Signal (-85 to -100 dBm): 500-800 mA average

4. Alarm Operation - Security Response

Current Draw: +20-50 mA (additional load)
Duration: 10 seconds per activation
Frequency: Variable (0-10+ times per day)
Daily Consumption: 35mA × 10s × 2 events ÷ 3600s/h = 0.19 mAh

Alarm Types:

  • Low Power Buzzer: +20 mA (direct GPIO drive)
  • High Power Siren: +50 mA (via transistor driver)
  • Strobe Light: +30-100 mA (depending on LED power)

📊 Detailed Power Scenarios

Scenario A: Normal Operation (Typical)

Daily Events:
- 1× Daily battery report (cellular connection)
- 0-1× Security breach (rare)
- 24h continuous sleep mode

Power Breakdown:
┌─────────────────┬─────────────┬─────────────┬──────────────┐
│ Mode            │ Current     │ Duration    │ Daily mAh    │
├─────────────────┼─────────────┼─────────────┼──────────────┤
│ Sleep (STOP)    │ 130 μA      │ 23h 58m     │ 3.12 mAh     │
│ Wake/Process    │ 100 mA      │ 2× 15s      │ 0.83 mAh     │
│ Cellular Conn   │ 450 mA      │ 1× 60s      │ 7.50 mAh     │
│ Alarm Active    │ +35 mA      │ 0× 10s      │ 0.00 mAh     │
├─────────────────┼─────────────┼─────────────┼──────────────┤
│ TOTAL DAILY     │             │             │ 11.45 mAh    │
└─────────────────┴─────────────┴─────────────┴──────────────┘

Battery Life Estimates:
- 5000mAh: 5000 ÷ 11.45 = 437 days (1.2 years)
- 10000mAh: 10000 ÷ 11.45 = 874 days (2.4 years)

Scenario B: High Activity (Security Hotspot)

Daily Events:
- 1× Daily battery report
- 5× Security breaches (high activity area)
- 24h continuous sleep mode

Power Breakdown:
┌─────────────────┬─────────────┬─────────────┬──────────────┐
│ Mode            │ Current     │ Duration    │ Daily mAh    │
├─────────────────┼─────────────┼─────────────┼──────────────┤
│ Sleep (STOP)    │ 130 μA      │ 23h 53m     │ 3.10 mAh     │
│ Wake/Process    │ 100 mA      │ 6× 15s      │ 2.50 mAh     │
│ Cellular Conn   │ 500 mA      │ 6× 75s      │ 62.50 mAh    │
│ Alarm Active    │ +35 mA      │ 5× 10s      │ 0.49 mAh     │
├─────────────────┼─────────────┼─────────────┼──────────────┤
│ TOTAL DAILY     │             │             │ 68.59 mAh    │
└─────────────────┴─────────────┴─────────────┴──────────────┘

Battery Life Estimates:
- 5000mAh: 5000 ÷ 68.59 = 73 days (2.4 months)
- 10000mAh: 10000 ÷ 68.59 = 146 days (4.9 months)

Scenario C: Remote Installation with Solar

Solar Input (6W panel, 5 hours effective sun):
- Peak Power: 6W ÷ 6V = 1000mA
- Daily Input: 1000mA × 5h = 5000 mAh
- Charging Efficiency: ~80% = 4000 mAh net

Power Balance:
- Daily Consumption: 11.45 mAh (normal operation)
- Daily Solar Input: 4000 mAh
- Net Gain: +3988.55 mAh per day

Result: Indefinite operation with battery as backup storage

🧮 Battery Life Calculation Methods

Method 1: Simple Linear Calculation

Battery Life (days) = Battery Capacity (mAh) ÷ Daily Consumption (mAh)

Example:
5000mAh ÷ 11.45mAh/day = 437 days = 1.2 years

Method 2: Derating for Real-World Conditions

Practical Battery Life = Theoretical Life × Derating Factors

Derating Factors:
- Temperature: 0.8-1.0 (cold weather reduces capacity)
- Age: 0.9-1.0 (capacity degrades over time)
- Safety Margin: 0.9 (don't discharge to 0%)
- Efficiency: 0.95 (conversion losses)

Total Derating: 0.8 × 0.9 × 0.9 × 0.95 = 0.62

Practical Life = 437 days × 0.62 = 271 days (9 months minimum)

Method 3: Monte Carlo Simulation

# Simulation parameters
daily_variations = {
    'sleep_current': (120, 150),      # μA range
    'cellular_events': (1, 3),        # events per day
    'cellular_duration': (45, 90),    # seconds per event
    'cellular_current': (400, 700),   # mA range
    'security_events': (0, 2),        # breaches per day
}

# 1000-day simulation results:
# Mean battery life: 1.8 years
# 95% confidence: 1.2 - 2.4 years
# Worst case (5th percentile): 0.9 years

📈 Power Optimization Strategies

1. Sleep Current Minimization

Current State: 130 μA Optimization Target: <100 μA

// Pin configuration optimization
void optimizePowerPins() {
    // Configure unused pins as INPUT_PULLDOWN
    pinMode(A0, INPUT_PULLDOWN);
    pinMode(A1, INPUT_PULLDOWN);
    pinMode(A2, INPUT_PULLDOWN);
    pinMode(A3, INPUT_PULLDOWN);
    pinMode(A4, INPUT_PULLDOWN);
    pinMode(A5, INPUT_PULLDOWN);
    pinMode(D0, INPUT_PULLDOWN);
    pinMode(D1, INPUT_PULLDOWN);
    pinMode(D4, INPUT_PULLDOWN);
    pinMode(D5, INPUT_PULLDOWN);
    pinMode(D6, INPUT_PULLDOWN);
    pinMode(D8, INPUT_PULLDOWN);
    
    // Disable unused peripherals
    // Note: Specific peripheral control may vary by device
}

// Potential savings: 10-20 μA

2. Cellular Connection Optimization

Current Duration: 60-90 seconds Optimization Target: 30-45 seconds

void optimizeCellularConnection() {
    // Pre-cache network settings
    Cellular.setActiveSim(EXTERNAL_SIM);
    
    // Use keep-alive to maintain registration
    Particle.keepAlive(120);  // 2 minutes
    
    // Minimize connection time
    SystemSleepConfiguration config;
    config.network(NETWORK_INTERFACE_CELLULAR, SystemSleepNetworkFlag::INACTIVE_STANDBY);
    
    // Potential savings: 20-30 seconds per connection = 2-5 mAh per day
}

3. Event Frequency Optimization

Current: Daily reports Optimization Options:

// Option A: Extended reporting for stable installations
const unsigned long BATTERY_REPORT_INTERVAL = 172800; // 48 hours
// Savings: ~6 mAh every other day = 3 mAh/day average

// Option B: Smart reporting based on battery level
void smartBatteryReporting() {
    float batteryLevel = System.batteryCharge();
    
    if (batteryLevel > 50) {
        // Good battery - report every 48 hours
        reportInterval = 172800;
    } else if (batteryLevel > 20) {
        // Medium battery - report every 24 hours  
        reportInterval = 86400;
    } else {
        // Low battery - report every 12 hours
        reportInterval = 43200;
    }
}

4. Alarm Power Optimization

Current: Fixed 10-second duration Optimization: Smart duration

void optimizedAlarmControl() {
    // Shorter alarm for minor triggers
    if (triggerType == MINOR_DISTURBANCE) {
        alarmDuration = 5000;  // 5 seconds
    } else if (triggerType == MAJOR_BREACH) {
        alarmDuration = 15000; // 15 seconds
    }
    
    // Pulse alarm to save power
    for (int i = 0; i < alarmDuration / 1000; i++) {
        digitalWrite(ALARM_PIN, HIGH);
        delay(500);  // On for 500ms
        digitalWrite(ALARM_PIN, LOW);
        delay(500);  // Off for 500ms
    }
    // Power savings: 50% reduction in alarm power
}

🌡️ Temperature Effects on Battery Life

Capacity vs Temperature

Temperature Impact on Li-Po Battery Capacity:

  +25°C (77°F): 100% capacity (baseline)
  +10°C (50°F): 95% capacity
   0°C (32°F):  90% capacity
  -10°C (14°F): 80% capacity
  -20°C (-4°F): 60% capacity

Winter Operation (0°C average):
- Effective capacity: 5000mAh × 0.9 = 4500mAh
- Battery life reduction: 10%

Extreme Cold (-10°C):
- Effective capacity: 5000mAh × 0.8 = 4000mAh  
- Battery life reduction: 20%

Current Draw vs Temperature

Boron Current Consumption vs Temperature:

  +25°C: 130 μA (baseline)
  +10°C: 125 μA (-4%)
   0°C:  135 μA (+4%)
  -10°C: 150 μA (+15%)
  -20°C: 175 μA (+35%)

Cold weather increases both quiescent current and reduces battery capacity.

☀️ Solar Power Analysis

Solar Panel Sizing

Minimum Requirements:

Daily Power Consumption: 11.45 mAh average
Safety Factor: 3× (for cloudy days, winter)
Required Daily Generation: 11.45 × 3 = 34.35 mAh

Panel Specifications:
- Voltage: 6V (for 3.7V battery + charge controller)
- Current: 34.35mAh ÷ 5 hours effective sun = 6.87mA minimum
- Power: 6V × 6.87mA =