What Boat Batteries Should You Buy?

Boat batteries are, in my opinion, the single most important piece of equipment you have on your rig. 

If you have years of experience with boats, or just beginning your boating adventures, no doubt you will deal with the frustrations of boat batteries at some time. If you are an avid bass angler, having battery issues can quickly ruin your day.

On your fishing boat, you will want to make sure you have both deep cycle and a cranking battery. The deep cycle will power your trolling motor while the cranking unit will start the big engine and run all the accessories. To have years of worry free trouble, I suggest AGM (Absorbant Glass Mat) batteries and a high quality onboard charger that conditions as well as charges your batteries.

To successfully choose the proper battery setup for your situation and budget, we will need to take a look at the different types of batteries and sizes. This will give you a great idea of what will work for you based on how many hours you spend on the water.

Deep Cycle vs. Cranking Batteries

As mentioned earlier, deep cycle batteries are designed to be charged and drawn down. These batteries will run your trolling motor and are at the heart of a successful and fun day on the water. Cranking batteries do exactly what they sound like – they provide the cold cranking amps needed to start the outboard motor and also provide power to things like livewells, electronic graphs, sound systems, anchors, power ports to charge your phone, etc.  

Most bass boats have one cranking battery but may have up to three deep cycle batteries. A trolling motor will either be 12 volt, 24 volt, or 36 volt. Deep cycles run on a 12 volt system, therefore a 12 volt trolling motor needs one battery, a 24 volt needs 2, and a 36 volt needs 3.

For your starting battery, you will see two different abbreviations, CCA and MCA. The first stands for Cold Cranking Amps and the second is Marine Cranking Amps. Cranking amps refer to the number of amps a battery can deliver for 30 sec. CCA is measured at 0° Fahrenheit. MCA is measured at 32° Fahrenheit.

Battery Types

There are three basic types of marine batteries that anglers will most likely find at their retailer. The traditional battery is called FLA, or flooded lead acid. This style of battery has been around a long time and requires more maintenance than other battery types.

AGM, or absorbant glass mat, batteries are completely sealed. The other type of sealed battery is call Gel. 

Batteries are also categorized by their group size. This terminology refers to the actual physical dimensions of the battery. If you have the room in your boat, I suggest purchasing the largest group size you can fit in the compartment. For most of us, that will be a Group 27 type battery. 

TypeCaseGroup SizeDimensions (LxWxH) inches
FLA (Flooded Lead Acid)Unsealed2410-1/4 x 6-13/16 x 9-3/4
FLA (Flooded Lead Acid)Unsealed2712-1/2 x 6-13/16 x 9-3/4
FLA (Flooded Lead Acid)Unsealed3113 x 6-13/16 x 9-7/16
AGM (Absorbant Glass Mat)Sealed2410-1/4 x 6-13/16 x 9-3/4
AGM (Absorbant Glass Mat)Sealed2712-1/2 x 6-13/16 x 9-3/4
AGM (Absorbant Glass Mat)Sealed3113 x 6-13/16 x 9-7/16
GelSealed2410-1/4 x 6-13/16 x 9-3/4
GelSealed2712-1/2 x 6-13/16 x 9-3/4
GelSealed3113 x 6-13/16 x 9-7/16

Advantages and Disadvantages

The most common, and affordable, battery type is the traditional FLA, or Flooded Lead Acid. These batteries have been the workhorse of the marine industry for years but have several disadvantages that need to be considered. First, FLA batteries need to always be mounted in an upright position or they will leak. Second, the water level needs to be checked to maintain battery health, and third, they are not as vibration resistant as other battery types. The major advantage is the price of FLA batteries. They are by far the most affordable.

AGM batteries are more expensive with some brands breaking the $300+ mark. They do have some huge advantages though. AGM batteries are sealed and can be mounted in any position. They are able to withstand more draw-down cycles and are very vibration resistant. It is not unusual for AGM batteries to last many years when paired with a quality onboard charger/conditioner.

Gel batteries are also sealed which means they are leak-free and can be mounted in any position. Like AGM batteries, they are also very vibration resistant. Gel batteries do have two considerable disadvantages though. They take longer to charge than either FLAs or AGM batteries. Gel batteries also tend to be more prone to shortened life span because of heat, although heat is a detriment to all battery types. 

In my opinion, bass boats are best served by using AGM batteries. The initial cost will be recouped over time and they will provide excellent service for years.

Onboard Charger

Once you have made the initial investment in your boat batteries, you will want to consider upgrading to a quality onboard charger. 

Onboard chargers offer tremendous convenience because the batteries can be hooked up all the time and not need to be removed from the battery compartment. There are a wide range of onboard chargers on the market, but I highly recommend using one that not only charges the batteries, but senses things like ambient temperature, voltage at the outlet and can handle all three battery types.

I myself have used the Minn Kota Precision chargers for years with tremendous success. I also want to let you know that I am not paid or sponsored by Minn Kota in any way. I really believe in this product and can fully endorse it because I have used them so long and seen the results. 

Amps per Bank

If you are new to the world of onboard chargers, you may not be familiar with how they are labeled. For example, they are rated per bank. So a three bank charger, which can charge three batteries at once, may have a label that says 30 amp. That will break down to 10 amps per bank. 

This is important if you want to buy the fastest charger. A charger rated for 15 amps per bank is going to charge your batteries much quicker than one that is rated as a 5 amp per bank charger. Naturally, the more amps per bank, the more the charger is going to cost.

Long-Term Storage

When batteries are used in-season, they do well with charging and draw-down. The real difference comes in when a boat is put up for the winter and not used for months. A quality battery and onboard charger makes all the difference when you pull the boat out in the spring.

With my battery setup, I am able to plug in my onboard charger and leave it, without worry, all winter long. I know that my charger will condition and take care of the battery health while the extreme cold temperatures hit. 

When the spring comes, I pull the boat out and my trolling motor runs all day without issue. It is a major piece-of-mind knowing that it is one less thing to stress about.

Cost of Boat Batteries

It can be a considerable investment to buy AGM deep cycle batteries, a cranking battery, and a high-end onboard charger. Depending on the voltage of your trolling motor that may mean three deep cycle batteries, one cranking battery, and a 4 bank charger. I would expect that to run just shy of $2,000 MSRP.

Final Thoughts

As I mentioned at the beginning of this article, the battery setup is the most important part of your bass boat. 

When your batteries and charger are functioning properly, you never pay attention to them. Yet, if there is trouble, there is no faster way to ruin a day on the water. It is frustrating to look forward to that outing all week and then have it shortened because of battery neglect. 

Put the investment in towards quality AGM batteries and top-end charger and I promise, you will have years of worry-free service and put a lot more fish in the boat.

Steve Rogers

Steve spends his time filming and writing about bass fishing. You may even see him in your area. If so, stop and say "hi."

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