hotel load

Hotel load is the continuous electrical demand from all onboard systems that operate independently of the propulsion engine. On a marine vessel, this includes lighting, galley equipment, air conditioning, navigation systems, and accommodation heating. On a truck or RV, it covers cab climate control, refrigeration units, sleeper berth heaters, and auxiliary systems. The term reflects the reality that a parked vehicle still demands power for basic habitability and operational readiness, much like a hotel running its systems when guests are stationary.

The magnitude of hotel load varies dramatically by application. A large commercial fishing vessel might draw 15 to 40 kilowatts continuously from hotel systems alone. A refrigerated transport truck could demand 5 to 15 kilowatts just to maintain cargo temperature and cab comfort during idle periods. This sustained drain is fundamentally different from peak propulsion loads, which are episodic and designed for short duration.

Power Supply and Storage Challenges

Hotel load creates a critical energy management problem. When an engine is shut down for rest, refueling, or cargo operations, hotel systems must draw from batteries or auxiliary generators. A marine vessel's hotel load might require a 100 to 200 amp-hour battery bank, or a diesel auxiliary generator rated at 20 to 50 kilowatts. Undersizing the power source leads to battery depletion and system failure; oversizing increases weight, cost, and fuel consumption. Some vessels run generators continuously while docked to supply hotel load, others switch to shore power when available.

The interaction between hotel load and propulsion capacity also affects vessel and vehicle design. A fishing boat with high hotel demand may need a larger main generator set than its propulsion alone would require. Trucks with heavy hotel loads sometimes carry dual battery banks or auxiliary power units (APUs) to prevent main engine drain. Shore connection systems on modern ships and trucks specifically address hotel load management by allowing the propulsion plant to remain offline while maintaining comfort and operational systems.

Estimating hotel load is essential for electrical system design. Engineers sum the rated power of all non-propulsion consumers: lights, pumps, compressors, heaters, electronics, and refrigeration. The resulting figure, typically expressed in kilowatts or amperes at the nominal system voltage, determines battery capacity, generator sizing, and charging system requirements. Uncertainty here leads to either dead batteries or unnecessary capital expenditure.