Auxiliary batteries are primarily used to power onboard devices when a vehicle is parked. Common applications include:

– Trucks and Buses: Providing power for air conditioning, lighting, entertainment systems, etc., enhancing comfort for drivers and passengers.
– RVs and Campers: Supplying electricity for refrigerators, TVs, lighting, and other devices, suitable for extended outdoor activities.
– Special Vehicles: Such as ambulances and fire trucks, powering medical equipment, communication systems, and other critical devices.
– Electric and Hybrid Vehicles: Powering auxiliary systems while parked, reducing the drain on the main battery.