Maintaining your boat’s battery is crucial for performance and increased service life. Keeping it properly charged can be an issue, particularly for vessels that see limited or sporadic use. Installing a modern “smart” battery charger is a great way to monitor and promote good battery health. Here’s a look at the basics, from selection to installation.

Selecting a charger
Marine grade batteries aren’t cheap and can easily be destroyed by improper charging, meaning the last place you want to skimp is when selecting a charger. Go with a good quality marine grade unit, ideally one built to American Boat and Yacht Council (ABYC) and Underwriters Laboratories (UL) standards. Look for smart chargers that provide numerous charging options and features such as the ability to select between the different types of battery technologies (i.e. wet cell, gel cell and absorbed glass mat).
As uncontrolled combustion is not our friend, battery chargers installed on a gasoline-powered vessel must also be labeled as being ignition protected. For PWCs and other open-type craft, you’ll want to go with a sealed, waterproof charger. Regardless of what you choose, stay away from those el cheapo automotive chargers down at the local Mart. They’re not designed for marine use and can cause a multitude of problems from stray current corrosion to shock hazards.
Always consult the manufacturer’s instruction when sizing your charger, but a general rule of thumb is to choose one with an output that’s at least 10 percent of your battery (or bank) capacity. For example, if you have a 300-amp-hour battery or bank, you’d want a 30-amp charger. If you can’t find an exact match based on the above, a charger with a little more output is better than one that’s too wimpy.