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1.8.3 AUX Battery Load Analysis

Scenario-based load analysis for AUX battery circuits (BCDC-charged at 50A max).

AUX Battery Circuit Summary

All circuits powered by AUX battery (charged by BCDC at 50A max):

Source Circuit Typical Peak Duty Cycle Notes
SwitchPros Outputs
OUTPUT-1 Roof Lights (8x XL Sport) 0A 18A Night offroad 2.2A per pod
OUTPUT-2 Ditch Lights (2x LP4 Pro) 0A 8A Night offroad Driving pattern
OUTPUT-3 Fog Light (1x S8 10") 0A 6A Night/weather Amber wide cornering
OUTPUT-4 Dome Lights (4x Cyclone) 0A 2A Doors open Manual + trigger
OUTPUT-5 Available 0A 0A — Freed by roof consolidation
OUTPUT-6 Rock Lights (6x Cyclone) 0A 3A Night offroad Under vehicle
OUTPUT-7 Chase Light (RTL-S) 0A 1A Night offroad Amber chase only
OUTPUT-8 Available 0A 0A — Footwell lights on MLC-RW
OUTPUT-10 Rear Locker 0A 2A Technical terrain Solenoid
OUTPUT-11 Compressor Control 0A 15A Control signal To ARB
OUTPUT-12 Rear Lights (2x S1 Pro) 0A 5A Night driving License plate
OUTPUT-13 Cargo Light 0A 5A Loading/unloading Trigger-2
OUTPUT-17 Front Locker 0A 2A Technical terrain Low-side
SafetyHub 150
MIDI-1 ARB Compressor Motor 1 0A 45A Airing up Half of twin
MIDI-2 ARB Compressor Motor 2 0A 45A Airing up Half of twin
ATC-1 Winch Trigger 0A 10A Recovery only Contactor coil
BODY PDU
CB30 Fusion Radio (memory) 1A 1A Continuous Clock/presets
CB44 Fusion Radio (amp) 0A 15A Audio playing Ignition-triggered
CB48 USB Charging (2x 75W) 2A 13A Devices charging Always on
CB39 WolfBox Camera 2A 10A Continuous Dash + backup
CB45 Driver Heated Seat 0A 5A Winter Relay K21
CB42 Passenger Heated Seat 0A 5A Winter Relay K22
CB43 Winch Control (dash) 0A 2A Recovery only Rocker signal
Direct
- Winch Motor 0A 400A 10-30 sec bursts Recovery only

Charging Source

BCDC Alpha 50: Charges AUX battery at up to 50A from START battery/alternator

  • Solar input: Up to 6.7A additional (80W panel)
  • Combined max: ~57A charging rate (sunny day, engine running)
  • Typical charging: 30-50A depending on AUX battery SOC

AUX Battery: Dakota Lithium DL+ 135Ah LiFePO4

  • Capacity: 135Ah nominal
  • Usable capacity: 108Ah (80% DOD safe for LiFePO4)
  • Heated BMS: Enables charging down to -4°F (critical for wheel well mount)
  • Recovery rate: At 50A charging, recovers 108Ah in ~2.2 hours

Scenario Analysis

Scenario 1: Daily Driving (Minimal Draw)

Conditions: Daytime driving, no offroad lights, radio off, no accessories

Circuit Load Reason
Fusion Radio memory (CB30) 1A Clock/presets
USB Charging (CB48) 2A Phone charging
WolfBox Camera (CB39) 2A Always recording
TOTAL 5A

BCDC Charging: 30-50A typical

Net Battery Effect: +25 to +45A (battery charging)

Battery SOC Trend: Rising - battery maintains full charge quickly

Scenario 2: Night Highway Driving

Conditions: Night driving, fog lights on, music playing, heated seats (winter)

Circuit Load Reason
Fog Light (OUTPUT-3) 6A Visibility
Rear Lights (OUTPUT-12) 5A License plate area
Fusion Radio memory (CB30) 1A Always on
Fusion Radio amp (CB44) 10A Music moderate
USB Charging (CB48) 5A Devices
WolfBox Camera (CB39) 2A Always recording
Driver Heated Seat (CB45) 3A Cycling
Passenger Heated Seat (CB42) 3A Cycling
TOTAL 35A

BCDC Charging: 50A (full rate)

Net Battery Effect: +15A (battery charging!)

Battery SOC Trend: Rising - battery maintains full charge even with high accessory use

Assessment: Excellent - 50A BCDC fully covers all night highway loads with margin to spare

Scenario 3: Night Offroad (Full Lighting)

Conditions: Technical trail at night, all forward lighting, rock lights, lockers engaged

Circuit Load Reason
Roof Lights (OUTPUT-1) 18A Primary forward
Ditch Lights (OUTPUT-2) 8A Peripheral
Fog Light (OUTPUT-3) 6A Close range
Rock Lights (OUTPUT-6) 3A Obstacle spotting
Chase Light (OUTPUT-7) 1A Following vehicles
Front Locker (OUTPUT-17) 2A Engaged
Rear Locker (OUTPUT-10) 2A Engaged
Fusion Radio memory (CB30) 1A Always on
USB Charging (CB48) 2A Phone
WolfBox Camera (CB39) 2A Recording
TOTAL 45A

BCDC Charging: 50A (full rate)

Net Battery Effect: +5A (battery charging!)

Assessment: Excellent - with corrected XL Sport specs (2.2A/pod), full night offroad lighting is now fully covered by BCDC charging. Battery maintains charge even with all lights on.

Scenario 4: Airing Up Tires (ARB Compressor)

Conditions: Parked after trail, engine idling, airing up 4 tires (5-10 minutes)

Circuit Load Reason
ARB Compressor Motor 1 (MIDI-1) 45A Running
ARB Compressor Motor 2 (MIDI-2) 45A Running
Compressor Control (OUTPUT-11) 15A Control signal
Fusion Radio memory (CB30) 1A Always on
USB Charging (CB48) 2A Phone
WolfBox Camera (CB39) 2A Recording
TOTAL 110A

BCDC Charging: 50A (full rate)

Net Battery Effect: -60A (moderate discharge)

5-minute air-up: 60A × (5/60)h = 5Ah used (5% of usable capacity)

10-minute air-up: 60A × (10/60)h = 10Ah used (9% of usable capacity)

Assessment: Excellent - minimal battery impact. Full recovery in 10-20 minutes of driving.

Scenario 5: Extended Airing Up (30+ minutes)

Conditions: Airing up 5 tires + air tank refill, extended compressor operation

Circuit Load Reason
ARB Compressor Motor 1 (MIDI-1) 45A Running
ARB Compressor Motor 2 (MIDI-2) 45A Running
Compressor Control (OUTPUT-11) 15A Control signal
Fusion Radio memory (CB30) 1A Always on
USB Charging (CB48) 2A Phone
WolfBox Camera (CB39) 2A Recording
TOTAL 110A

BCDC Charging: 50A (full rate)

Net Battery Effect: -60A (moderate discharge)

30-minute operation: 60A × 0.5h = 30Ah used (28% of usable capacity)

Time to 20% SOC: 108Ah / 60A = 108 minutes of continuous compressor operation

Assessment: Extended air-up no longer a concern. Can run compressor for nearly 2 hours before reaching 20% SOC.

Scenario 6: Winch Recovery (Brief High-Current)

Conditions: Vehicle recovery, 30-second winch pull at moderate load

Circuit Load Reason
Winch Motor 250A Moderate pull
Winch Trigger (ATC-1) 10A Contactor coil
Winch Control (CB43) 2A Dash rocker
Fusion Radio memory (CB30) 1A Always on
WolfBox Camera (CB39) 2A Recording
TOTAL 265A

BCDC Charging: 50A (full rate)

Net Battery Effect: -215A (heavy discharge)

30-second pull: 215A × (30/3600)h = 1.8Ah used (1.7% of usable capacity)

Assessment: Winch operations have negligible battery impact. Can perform 50+ pulls before approaching 20% SOC.

Scenario 7: Camp Mode (Engine Off)

Conditions: Parked at camp, engine off, minimal lighting, music

Circuit Load Reason
Dome Lights (OUTPUT-4) 4A Camp lighting
Rock Lights (OUTPUT-6) 3A Ground lighting
Footwell Lights (MLC-RW) 1A Ambiance
Fusion Radio memory (CB30) 1A Always on
Fusion Radio amp (CB44) 8A Music
USB Charging (CB48) 10A Multiple devices
TOTAL 27A

BCDC Charging: 0A (engine off)

Solar (daytime): ~5-6A (80W panel)

Net Battery Effect (day): -21A

Net Battery Effect (night): -27A

Time to 20% SOC (no solar): 108Ah / 27A = 4 hours

Time to 20% SOC (with solar): 108Ah / 21A = 5+ hours (daytime only)

Assessment: Camp mode now practical. 4+ hours of music, lights, and charging without engine. For extended camping:

  • Solar extends daytime runtime significantly
  • Idle engine 30 min to recover ~25Ah
  • Multi-day camping still benefits from periodic charging

Summary

Scenario Total Draw BCDC Net Effect Time to 20% SOC Status
Daily Driving 5A 50A +45A N/A (charging) Excellent
Night Highway 35A 50A +15A N/A (charging) Excellent
Night Offroad 45A 50A +5A N/A (charging) Excellent
Air Up (5-10 min) 110A 50A -60A 108 minutes Excellent
Air Up Extended 110A 50A -60A 108 minutes Excellent
Winch Recovery 265A 50A -215A 50+ pulls Excellent
Camp Mode 27A 0A -27A 4 hours Good

Key Insight: With corrected XL Sport specs (2.2A/pod vs 6A), full night offroad lighting (45A) is now fully covered by 50A BCDC charging. The Dakota Lithium 135Ah upgrade provides effectively unlimited runtime for all driving scenarios including full lighting. Camp mode provides 4+ hours without engine.