If you've ever wondered whether your batteries are charging efficiently when your engine is running, you've probably thought about your alternator. Alternators come in all shapes and sizes - so if you're thinking about upgrading there are a few things you should take into consideration.
You can typically increase the power output of your alternator by upgrading to a larger model. However, your engine has a maximum alternator power rating. Using an alternator above this rating will impede your engine's proper operations and could damage it as well.
An externally regulated alternator (with the same power rating as an internally regulated alternator) will provide more power to your batteries, but is more complicated to install. It requires both an alternator designed for external regulation, and an external regulator set up properly. Most regulators can be fitted with a battery temperature sensor to cut off the power in case the batteries become too hot from overcharge. This is the best solution if increased power is the goal.
A slipping alternator belt can also reduce the amount of power from your engine, so make sure that it is properly tightened.
Finally, alternators come with different casings. It's a great idea to bring the alternator that was removed from your engine with you to purchase a new one. This way you can make sure that your new alternator will fit the mounting brackets on your boat.