What size battery for mercury 4 stroke 50 hp outboard?

For a Mercury 4-stroke 50 hp outboard, a recommended battery size is typically a Group 24 or Group 27 deep-cycle or starting battery. These batteries usually have a capacity of around 70-100 amp-hours, providing sufficient power for starting and operating the engine. It's important to ensure that the battery voltage matches the outboard's requirements, which is generally 12 volts. Always consult the owner's manual or a dealer for specific recommendations tailored to your engine model.