Skip to content

Understanding Your Boat Battery Voltage

Understand your boat's charging needs

You can’t charge your boat battery before you know the voltage of your boat’s electrical system. At the same time, it helps to understand the different types of charging options that you can use while you’re on the go or tied-up in an unfamiliar marina or dock.

Check out this brief primer on boat batteries, their voltage needs and your charging options.

24-Volt Versus 12-Volt

The vast majority of small watercrafts — boats under 40 feet in length — borrow their charging systems from automotive designs. This means that they make use of 12-volt batteries that can be charged at a rate of no more than 14.4 volts in order to prevent damage to their circuits.

If you own a larger boat, then there’s a strong chance you’re actually operating on a 24-volt charging system. Big boats have more intense power needs and using a 24-volt system is more efficient at meeting the demands of lighting, bilge pumps and other electrical systems than a 12-volt system.

Verifying whether your boat operates at 12 volts or 24 volts is a crucial first step in understanding your charging options. You can’t connect one type of boat battery to another type’s charging system without risking either damage or no charge at all.

Boat in marina

Charging Options

The simplest portable boat battery charger is a solar design, which you can mount on a pole or on any flat part of the boat that won’t get covered in spray or grime during your trip. Keep in mind this type of charger is typically only good for keeping a trickle or “float” of power flowing into your battery. While it will keep things topped off, it won’t recharge a larger battery that’s been drawn down after a long period of motor-free operation.

If your battery has been deep-cycled — that is to say, drawn down significantly after an extended time at anchor — you’ll need a battery charging system that is capable of multistage battery charging. Multistage charging addresses both the need to fill a deeply cycled battery and switch to a float-type charge to keep it topped off.

It’s important to understand your boat’s charging needs before you tie-up at the marina. When docked, verify which type of charging solutions are available, check the status of your battery’s voltage and then connect to the appropriate charger.

Check out all of the batteries available on NAPA Online or trust one of our 17,000 NAPA Auto Care locations for routine maintenance and repairs. For more information on boat batteries, chat with a knowledgeable expert at your local NAPA Auto Parts store.

Photo courtesy of Morguefile

Benjamin Hunting View All

Having been bitten by the car bug at a young age, I spent my formative years surrounded by Studebakers at car shows across Quebec and the northeastern United States. Over ten years of racing, restoring, and obsessing over automobiles lead me to balance science writing and automotive journalism full time.  I currently contribute as an editor to several online and print automotive publications, and I also write and consult for the pharmaceutical and medical device industry.

Leave a Reply

Your email address will not be published. Required fields are marked *