Boat Batteries: Choosing The Right Marine Battery

These days, it seems like we put more stress on the power source in our boats than ever before. Everything from radios and livewells, to outboard and trolling motors require power – even cell phones, tablets and bluetooth speakers are being powered and charged by a boat’s electrical system. Without the right battery or charging system, you can find yourself literally dead in the water. That’s why it’s so vital to get the most out of your onboard batteries. With that in mind, I wanted to take a quick moment to offer some insight into selecting the right battery and charger for your boat.

When talking about batteries, it’s important to start with what you’re using them for. Very few boats these days are running on simply one battery and that’s due to the power needed to run all of your various applications. The two key decision points in batteries are type and chemistry.

Choosing the right marine battery for your boat

Above: Choosing the right marine battery for your boat can be tricky. Sean Budiac, Vice President of Category Management with Batteries Plus, walks boaters through some tips and considerations when selecting the best boat battery for your vessel.

Boat Battery Types: What’s The Best Boat Battery For You?

Let’s start with type. There are three basic types of boat batteries: starting, dual-purpose and deep cycle.

Starting Batteries

If your battery is just there to start the motor, a fully charged, ready-to-go starting battery is truly all you need. It delivers a ton of cranking power to start the motor, which is all it’s really designed to do.

Dual-Purpose Batteries

In my boat, the battery that starts the motor also runs my radio, livewell, electronics and lights. For me, I rely on a dual-purpose battery to power those accessories but still start my motor.

Deep Cycle Marine Batteries

These batteries are designed for the sole purpose of running accessories and are usually used together with a starting battery. Deep cycle batteries power applications such as radios, lighting, electronics (graphs), trolling motors and charging outlets.

Now that you know what type of battery you need, go check your battery compartment. Sadly, it’s all too common to find owners using the wrong types of batteries. Last year, I bought a used boat that had two starting batteries hooked up to the trolling motor, rather than the deep cycle battery it required. You can bet those got replaced right away.

Battery Chemistry: How Boat Batteries Work

Now on to chemistry. When it comes to boats, there are four chemistry types: flooded, AGM, Flat Plate AGM and Lithium.

Flooded Batteries

These batteries have been around for ages. They provide lots of power when matching the battery to an application, but they do need to be maintained. Fluid levels will need to be checked and topped off regularly. Flooded batteries are reliable and affordable, but provide less power than their AGM counterparts.
AGM – Stands for Absorbed Glass Mat. These batteries outperform their flooded counterparts in starting power, reserve capacity (the accessory power) and life span. A great AGM battery will last you years if properly maintained.

Flat Plate AGM Batteries

A fancy name for a special type of dual-purpose AGM battery that features lots of flat lead plates that create energy. These flatter plates allow you to squeeze more of them into a battery, producing much more power. This additional power allows them to function as both a starting and deep cycle battery in one. X2Power marine batteries are some of the best AGM batteries on the market, providing the best starting power, reserve capacity, charging speed and life. The X2Power 31 Marine is the exact battery I use to start my engine, power my trolling motor and run any additional accessories.

Lithium Batteries

This is the latest technology to hit the marine market. High-powered and very lightweight, with an ability to push out consistent power during the entire charge cycle. While a great power source, lithium batteries are new to the market and have a higher upfront investment than AGM or flooded batteries.

Now that you’ve figured out the right battery for your boat, let’s talk charging. Too many times I hear stories of people with boats out on the water, fishing rods ready to go only to find the trolling motor batteries are dead…don’t be that person. The big decision with chargers is whether or not to install an onboard charger. For me, I would never do it any other way. Below are your options and a few examples of each.

Onboard Battery Chargers

This type of charger is permanently installed in your boat and connected directly to each and every battery. Run the extension cord to your boat and plug it into the charger and you are set to go. These come in configurations that will match the number of batteries in your boat; mine charges all three at the same time. The SLC10017 Duracell Ultra Automatic Marine Battery Charger has a hardened outer casing protects against water, dirt, UV, and pressure impacts. It is water resistant up to 4.9 feet (1.5 meters) and its 4-amp charger can keep a boat battery ready to go as well as be permanently mounted to battery housing on/inside boat.

The SLC10207 is a one-bank on-board battery charger (rated at 10-amps for 12-volt batteries, including marine, boat, starter and deep-cycle batteries) that helps maintain boat batteries and is a battery desulfator as well. An integrated thermal sensor detects the ambient temperature and alters the charge to eliminate over-charging in hot climates and under-charging in cold climates. It’s not just a trickle charger, it’s an advanced battery maintainer. A fully-automatic, worry-free battery charger for everyday use – 24/7 – with zero overcharge

Stand Alone Battery Chargers

Most boat owners have probably used one of these at some point. Pull the battery out of the boat, bring it to the charger, charge the battery, then reinstall. For me that’s too much work. But, if you have one battery in your boat that is easily accessible, it can be a great option. Plus, the benefit here is it can be used on other 12V batteries for your car or lawn mower.

The SLC10005 X2Power 7.5 Amp Charger is an example of a stand alone charger that works great for marine battery applications. It is built for charging advanced AGM battery designs and is compatible with flooded, gel, AGM and lithium batteries. Another great example is the SLC10165 NOCO GENIUS10 10 Amp automatic battery charger and maintainer which is designed for either 6V or 12V lead-acid automotive, marine, deep-cycle batteries and lithium ion batteries and can charge dead batteries as low as 1V, via a unique, built-in “Repair Mode” that brings dead batteries back to a readable levels.

Using the right battery and charger can make the difference between a fun weekend on the water or a day of disappointment. I hope this has helped provide some insight into how marine batteries work. Remember, any questions you have can always be answered by the experts at your local Batteries Plus store or through browsing other educational boating articles on the resources section of Boat Trader.

Have a great summer on the water!

Written by: Shawn Budiac

Shawn Budiac is the Vice President of Category Management with Batteries Plus and has over 15 years of experience working in the retail industry. In his current role, Budiac specializes in developing procurement strategies for the retailer’s inventory including marine batteries, boat electronics and accessories.

Related