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Battery Management

Power consumption, charging, and battery lifecycle.

Battery Model

State of Charge (SoC)

Battery level as percentage (0-100%):

SoC = current_charge / capacity × 100%

Key Parameters

Parameter Description Example
capacity_wh Total energy capacity 500 Wh
initial_soc Starting charge level 100%
consumption_rate_w Power draw while operating 50 W
charge_rate_w Charging power 200 W

Power Consumption

Consumption During Operation

Battery drains during:

  • Traveling: Higher consumption
  • Idle: Lower consumption
  • Working: Variable

Consumption Formula

energy_used = power × time
SoC_new = SoC_old - (energy_used / capacity)

Example

Robot traveling for 60 seconds at 50W:

Energy = 50W × 60s = 3000 Ws = 0.833 Wh
If capacity = 500 Wh:
  SoC drop = 0.833 / 500 = 0.17%

Charging

Charge Time

Time to fully charge:

charge_time = capacity × (1 - current_soc) / charge_rate

Example

Battery at 20%, capacity 500 Wh, charge rate 200W:

Energy needed = 500 × (1 - 0.20) = 400 Wh
Time = 400 Wh / 200 W = 2 hours

Charging Process

Battery: [████████████░░░░░░░░] 60%
         ↓ Charging at 200W
         ...
Battery: [████████████████████] 100%

Charging Triggers

Threshold-Based

Charge when SoC drops below threshold:

battery:
  charge_threshold_pct: 20

Robot automatically goes to charge at 20% SoC.

Opportunistic

Charge during idle periods:

battery:
  opportunistic_charging: true
  opportunistic_threshold_pct: 80

Charge when idle and below 80%.

Scheduled

Charge at specific times or intervals.

Charging Station Behavior

Station Selection

How robots choose charging station:

Policy Behavior
nearest Closest station
shortest_queue Least congested
highest_capacity Fastest charging

Queue Management

Charging Station CS1 (3 bays):
  Bay 1: [R5] charging (45%)
  Bay 2: [R8] charging (72%)
  Bay 3: [R2] charging (95%)
  Queue: [R11] → [R3]

Battery Impact on Operations

Task Interruption

Low battery may interrupt tasks:

Task T1: Traveling...
  → Battery at 18% (< 20% threshold)
  → Task paused
  → Robot goes to charge
  → Resume task after charging

Task Feasibility

Check if robot can complete task:

Required: Travel (10m) + Work (60s) + Return (10m)
Energy needed: ~15 Wh
Current SoC: 25% = 125 Wh available
  → Task feasible ✓

Range Anxiety

Conservative threshold prevents stranding:

Safe threshold = max_task_energy + reserve

Configuration Example

battery:
  # Battery capacity
  capacity_wh: 500

  # Initial state
  initial_soc_pct: 100

  # Consumption
  consumption_rate_w: 50
  idle_consumption_rate_w: 10

  # Charging triggers
  charge_threshold_pct: 20
  charge_target_pct: 95

  # Opportunistic charging
  opportunistic_charging: true
  opportunistic_threshold_pct: 80

Battery Metrics

Key Performance Indicators

Metric Description
Average SoC Mean battery level across fleet
Charge events Number of charging sessions
Charge time ratio Time charging / Total time
Deep discharge events Times SoC < critical level

Fleet Battery Distribution

SoC Distribution:
  0-20%:  ██ (5 robots)
  20-40%: ████ (10 robots)
  40-60%: ████████ (20 robots)
  60-80%: ██████ (15 robots)
  80-100%: ████████████ (30 robots)

Best Practices

Threshold Selection

  • Too low (10%): Risk of stranding
  • Too high (50%): Excessive charging, reduced utilization
  • Recommended: 15-25%

Charging Infrastructure

  • Station count: Enough for peak demand
  • Station placement: Distributed across warehouse
  • Bay capacity: Multiple bays reduce queuing

Monitoring

Track these indicators:

  • Robots frequently below threshold
  • Long charging queues
  • Tasks delayed due to charging