Marine Battery Chargers, Batteries & Accessories

Boating Know How
Batteries and Chargers for a Boat

Basics to Finding the Right Battery Charger

The most fundamental component of your boat's electrical system is the battery, which is why we carry a huge selection of marine-grade battery chargers, battery boxes, trays, ties downs, switches, battery isolators, terminals, inverters and more. ... read more Some of the competition may offer non-marine-grade batteries and components; don't be fooled! When you shop at you can be confident that the battery parts and accessories you buy are made by brands such as Ancor, ProMariner, Xantrex, Guest, Minn Kota and SeaSense, which manufacturer products specifically designed for your boat and it's harsh and wet marine surroundings.

With so many battery chargers on the market and  a massive variety of specs and features, finding the right charger for your boat can seem quite daunting.

The first step will be to do is qualify the attributes of the battery charger you plan to purchase.  This includes determining the type of battery charger you'd like to use, how many batteries you want to charge at once (banks), amperage you'd like batteries charged at, AC input voltage, DC output voltage, and battery compatibility.  The fact that features & attributes are mixed-and-matched to form specific products means there are a lot of options, but most features and attributes have little variations, making the decision making process simple.

For example if you limit your boating to the USA, you know you'll need a charger that provides an AC input voltage range that includes 120 volts.  Have 3x lead-acid 12VDC batteries?  You'll need a 3-bank 12v battery charger compatible with lead-acid batteries.

For a more thorough break-down of the standard features and options used by most onboard boat battery chargers, check-out our battery-charger guide at the bottom of this page.
read less

Blue Sea Systems Tech Tip: Automatic Charging Relays Explained

Here you can learn about Automatic Charging Relays, Battery Isolators, and Zero Drop Isolators.
... read more Infographic: Automatic charging Relays Explained

Automatic Charging Relays allow two banks on a vessel's alternator to be charged simultaneously from one unit. Doing so, keeps the batteries isolated when not charging. This benefit is useful in the case of one battery failing and having another battery as an emergency back-up. There are a few main styles to choose between:

  • Automatic Charging Relays: Combined voltage and relays that reach over 13V DC will charge two batteries at the same time. When the charge is inactive or overloaded, the voltage will drop to around 12.75V DC. The relay will open, and the two batteries will be isolated. An Automatic Charging Relay allows the current to pass easily from one battery to the next.

  • Battery Isolators: Currents will flow more swiftly to the battery. However, because of the presence of diodes, the voltage is more likely to decrease, which consumes more energy and does not charge batteries quite as quickly. Also, the heat levels will most likely rise, and the currents will split.

  • Zero Drop Isolators: These isolators are useful in addressing the problem of voltage- dropping. These will cost more than the other options due to limited market acceptance.

Applying one of these three concepts to your alternator will bring about different advantages and will inevitably improve the lifespan and quality of your batteries. We recommend, for the sake of safety and accuracy, consulting with a technician or a mechanic in choosing the appropriate method before making any purchases.
read less

Blue Sea Systems: Add-A-Battery Explained

Learn about the importance of adding a second battery to your boat to ensure your boat starts.
... read more Infographic: Add-A-Batter Kits Explained

A common inconvenience you should always be ready to remedy is batteries that die and refuse to start. Failure to observe your battery and prevent this from happening early on will require you to tow your boat to a mechanic. And, taking your boat to the mechanic will take up a lot of unnecessary time and money. If you run into this problem, there is a solution: obtain a second battery for the electrical system. Specifically, the Add-A-Battery kit contains a Dual Circuit Plus Battery switch, along with an Automatic Charging Relay (You may choose between either battery isolator or zero drop isolators).

Once installed, the system takes care of itself, requiring only to flip an on/off switch when you are on or off the deck. Investing in a second battery would be particularly useful in unpredictable circumstances. Having a second battery will lessen the chance and risk of getting stranded out on the water. This battery collects its energy and power from linking to one single charge source known as the House battery. The House battery is the original battery before the addition of a second battery.

When the engine is turned on, the Automatic Charging Relays combine the two energies of the House battery with a second battery. When the engine is turned off, the energy is completely excluded to the House battery. The Automatic Charging Relays isolate the batteries when they are being discharged. Add-A-Battery kits are practical and useful, and they play a crucial part in preventing batteries from going dead and keeping boaters from being stranded.

read less

Blue Sea Systems Tech Tip: Battery Charging Explained

... read more Infographic: Battery Chargers Explained read less