The Complete Guide to Buying Boat Batteries: Everything to Know

What are the best times of day to go fishing?

Morning and evening.

Morning is the perfect opportunity to snatch up a great catch as wildlife activity picks up. And evenings produce optical temperatures for fish to hang out feeding. Of course, you’re not going to have very much fun fishing if your boating battery dies halfway through the day.

To avoid having a boating fiasco, we’ve created this short guide. We’ll walk you through the top tips for buying boat batteries, so you can get back out to enjoy nature.

What type of marine battery do you need? Read on to find out!

Top Boat Battery Options

You want to begin by familiarizing yourself with the two basic types of boat battery options. First, you have the deep cycle batteries. Deep cycle batteries, like, are used to power different electrical accessories such as fish finders, radios, and even trolling motors.

Next, you have cranking or otherwise called starting batteries. As their name suggests, starting batteries start your boat’s main engine.

You can choose to get dual-purpose batteries that perform both deep cycles and cranking functions. However, sometimes dual-purpose batteries aren’t as efficient as single source options.

Internal Battery Design

When buying boat batteries, it helps to know the internal designs. The internal design for each battery is entirely different. However, at first glance, they’ll appear to be the same on the outside.

Similar to standard batteries, the starting battery has a tiny plate that surrounds an electrolyte. The thin plates can then produce a large number of amps in just a short period.

A deep cycle battery takes a different approach using much thicker plates. The deep cycle battery will draw electricity over a more extended period and at a more steady rate.

You wouldn’t want to try to use a deep cycle battery as your engine starter. The deep cycle battery will have the short-term muscle strength to start up a cold engine.

Comparing Battery Costs

As you begin comparing battery cost, you’ll notice that the batteries come in a wide variety of sizes. Standard marine battery terms include categorizing the batteries as 24, 31, 27, 4d, and 8d.

The battery group doesn’t suggest the capacity of the battery. Instead, the group number lets you know the battery’s physical size.

The capacity of the battery is going to be given as amps. Amps are short for amperes, and it refers to amp hours.

Theoretical Capacity

Of course, the capacity is theoretical. Batteries don’t work uniformly in every situation. If your battery has a discharge rate greater than 50% of the battery’s total capacity will not perform as efficiently. Plus, if you’re using the battery when it’s low on juice, you’re also going to be altering the capacity.

Another thing to consider is that a battery that runs at 100 amps will lose efficiency as it ages. If you currently have 100 amp batteries, but you’re not getting that much juice out of them, it’s probably because it’s time to replace them.

Different Types of Battery Chemistry

Manufacturers are going to take different approaches to create starting engine batteries and deep cycle batteries. One approach is flooded batteries.

Flooded batteries use a supply of sulfuric acid that’s in a liquid form. This type of power produces hydrogen and oxygen as the batteries begin to charge. Flooded batteries also have vented cells that allow the gas to escape safely.

When it comes to boat battery maintenance, flooded designs require a lot more attention. On the outside, flooded batteries are lovely for overcharging situations. If you accidentally overcharge the battery, you won’t have to worry about causing permanent damage.

Another advantage is that flooded batteries tend to be cheaper than the other options. One of the reasons they’re cheaper, though, is because they are less resilient against shocks and vibrations.

Gel Type Batteries

If you want a battery that can handle any type of vibration, go with gel-type batteries. A gel power cell uses a gel-type electrolyte to keep things extra safe. Modern gel batteries are maintenance-free, waterproof, leakproof, and efficient.

Using a lower rate of self-discharge, the gel battery engineering eliminates gassing. You’ll find that gel-type batteries are even safer and easier to install, making them more convenient for everyday boating.

Lithium Iron Batteries

If you want the latest battery technology, then you’ll need to go with lithium-ion batteries. Lithium-ion batteries have a ton of pros, including a longer run time, fast recharging rate, and more electrical capacity.

After being invented back in the 1800s, scientists have evolved the design for lithium-ion batteries. New generations of highly efficient batteries with extra electrical energy storage are now hitting the market.

You’ll also be able to enjoy a lighter, sleek design. The downside to lithium-ion batteries is that they are going to cost a lot.

However, you’ll be making an investment that will pay off over time, instead of having to replace your batteries frequently like you would with flooded batteries, lithium-ion batteries last year after year.

AGM Batteries

Finally, there are also AGM batteries which stand for absorbent glass mats. AGM batteries use a power cell with a dry electrolyte.

The most significant advantage of AGM batteries is that they have a vast storage capacity. You’ll be able to enjoy a higher amount of cycles, which means I’m a more efficient runtime.

Many boaters find AGM batteries to be the perfect medium between flooded batteries and expensive lithium-ion batteries.

What Are Your Boating Needs?

To decide which battery type will work best for you, you’ll need to determine the needs of your boat. What is the entire electrical load of your boat?

What type of current will you need to start your engine? Your marine battery is going to have to handle both tasks.

The battery needs to be able to start the engine and operate the boat’s entire electrical grid. If you underestimate the power you’ll need for either of these activities, then you’re not going to go far on the water.

Cold Weather

Keep in mind that cold weather can make it hard for batteries to start an engine. To overcome this problem, we suggest investing in a cold cranking amp marine battery. You’ll be able to get all of the power you need, no matter what type of low-temperature condition you’re dealing with.

Start Buying Boat Batteries

Now you know the ins and outs of buying boat batteries that meet all of your needs.  Deep cycle batteries are the way to go for running the boat’s grid. Whereas, if you need to replace the batteries that help start your engine, a crank-style battery is an intelligent choice.

Finally, decide what type of design you want your battery to have. Will it be a gel battery? Or are you going to opt for advanced lithium-ion batteries?

Start shopping for a boat battery today. For more tips like these, see what the rest of our blog has to offer.