What size battery for a 150 hp mercury outboard?

For a 150 hp Mercury outboard, a 12V battery with a minimum capacity of 800 CCA (cold cranking amps) is typically recommended. A group size 27 or 31 battery is often suitable, as they provide adequate power for starting and running the motor. It's also advisable to consider a deep-cycle or dual-purpose battery to support additional electrical systems on board. Always check the manufacturer's specifications for the most accurate recommendations.