Everything You Need to Know About Marine/Boat Batteries

Marine batteries, commonly known as boat batteries, are just as important to think about maintaining as your car battery. Proper care makes sure when you’re taking the boat out for the first time in the spring or summer, you’re not left with an unexpected dead battery. Here’s what you need to know about the maintenance and care for your marine batteries.

The Kind Of Battery Do You Need

The kind of battery you’ll want on board depends on what you need the battery to do (many boat batteries are deep cycle batteries). Sounds practical enough, but think about more than just starting your boat.

If you have a simple motor and no electrical gadgets to speak of, then a cranking battery will do the trick. However, if you have any electrical equipment like a GPS, depth finder or even a radio, you’ll want to check out a deep-cycle battery.

Cranking Battery – it’s main purpose is just to start the engine by providing a quick burst of energy. This means while they aren’t reliable to keep your radio going all day, they are more than up to the task of getting your boat going for that early morning fishing trip.

Deep-Cycle – a deep cycle battery offers a lower and more steady rate of energy than the cranking battery. This means that you can run all of your electrical equipment without the risk of having to charge your battery on the water.

Deep cycle batteries are also great if you need to power a depth finder, live well, bilge pump, GPS, fish locator etc.

Because these types of marine batteries are used for different purposes, they aren’t interchangeable. Make sure you stick with the battery type your boat was designed for. Attempting to use a battery that is not designed for your specific type of boat can lead to battery failure, or worse. If you want to learn more about different batteries in general, check out some basic battery knowledge.

Maintaining Your Battery

The maintenance your battery will require depends on the chemistry and construction of the battery you have.

Wet-Cell Battery – the most common and typically the most affordable. They contain many cells with an electrolyte liquid most of us call battery acid.

Allowing the fluid levels to get low can lead to the battery’s early demise, so it’s important to refill the cells with distilled water. While this may seem like doing a lot, there are advantages to a wet-cell battery:

  • They are generally lighter in weight than other batteries
  • Generally have a longer life cycle

*One major downside to having a wet-cell battery on a boat is their susceptibility to the boat vibrations

Lithium-Ion – the newcomer to the battery world is proving to be a star, but be warned, this high-performance battery comes with a high-end price.

  • They are lightweight and carry a deep charge
  • They also have the longest life cycle of all the batteries and can be recharged faster and more times over the course of their life

*If your boating passions depend on high performance, then splurging on a powerful lithium-ion battery may just be worth it.

Gel Battery – Gel batteries are filled with electrolyte similar to the wet-cell battery, with the primary difference being that the liquid is turned into a gel. This eliminates the need to replenish the cells with water.

  • These batteries are generally maintenance free and have a greater resistance to the boat vibrations
  • Their rate of self-discharge is fairly low as well, which means they can be stored throughout the winter without having to be recharged as often

*The drawbacks here are the cost and the need for special equipment. Gel batteries can cost two times that of a wet-cell battery and they require a special charger.

AGM Battery – AGM or Absorbed Glass Mat batteries have a fiberglass mat that is soaked in the electrolyte and placed between the battery plates.

  • This construction means that there is no need to refill the cells
  • Able to withstand higher vibration rates

*AGM batteries are also heavier than a traditional wet-cell battery, and are unforgiving if inadvertently overcharged.

Long Term Care

All boat batteries need to be cleaned and cared for just like the rest of your boat. While you are wiping down the boat, take some time to look at your battery. Remove any dirt or corrosion that may be building up.

This simple action will add life to your battery and slow down its rate of self-discharge. Make sure no cracks or malformations appear in the casing. If so, it could mean a problem with the voltage and you’ll want to have it checked out. If you’re getting ready to store for the winter, make sure you store all marine batteries fully charged and in a climate controlled environment. Chargers may just be accessories, but using a top quality marine battery charger is a great product to have, since you never want to store a battery that’s discharged.

You can either attach the battery to a trickle charger to keep it charged throughout the winter, or check it at least once a month and recharge as necessary.