Sailboat Battery Usage

Batteries are a vessel’s major source of power for many essential functions both when in the slip and while sailing. These include:

• Engine starting
• Bilge pump(s)
• Running lights required for nighttime sailing
• Cabin lights
• Raising anchors—although most anchor winches require that the engine is idling at about 1500 rpm
• Power winches
• Windlass
• A wide variety of navigation and communication instruments
• Refrigeration
• Entertainment devices such as stereo, TV, and DVD player
• Electric flushing heads
• Water pump
• Cabin fans
• Macerator
• Starter solenoid for the gas oven
• Electric outboard engine for the dingy
• Small battery chargers

Modern vessels are loaded with many appliances that consume electrical power, even when turned off. Before adding any appliance to the vessel, it is essential to know the impact it will have on your systems to ensure power consumption viability, function, and safety. For example, if you have a 12-volt DC refrigerator that you wish to keep running at all times, you must maintain a charged battery for it.

By far, one of the bigger power consumption devices on a boat is the windlass (the anchor winch), which can draw upwards of 100 amps at 12 volts. Thus, it is a good idea to run the engine anytime you are using the windlass. Some boats are wired so that the engine must be running.