How to choose the right marine battery

Battery storage tips and state of charge dos and don’ts
19/07/2018

We all have serious need for electricity onboard and a good working battery is one of the most important crew members. It’s not encouraging, yet it’s a fact: batteries degrade over time. At some point, you shall be looking forward to buying a new one.

It’s important that you choose the right battery for your boat. But … which is the right one? It’s very difficult to select as there are countless choices. The most important factor that you must consider is the purpose of the battery.

Do you require a battery only for starting the boat or also for running the various power-hungry electronics onboard? Or perhaps both. According to the demand of usage, basically there are three types of marine batteries:

  • cranking battery,
  • deep cycle battery,
  • dual purpose battery.

Other basic considerations before purchasing a new battery are:

  • battery capacity (Ah rating),
  • battery group, i. e. battery’s physical size (make sure the battery perfectly fits in the battery box),
  • weight (choose the battery with average weight to be able to move it in and out),
  • output (marine cranking amp rating, reserve capacity rating, cold cranking amp rating),
  • technology (flooded, gel, AGM, lithium-ion; gel and AGM are maintenance-free sealed batteries),
  • warranty.

Check your owner’s manual for the recommended battery types and ratings. Substituting the recommended battery type for the other is generally not a good idea. Always choose along with the rating equal to or greater than the recommended value.


Cranking or starting marine battery

These types of batteries offer high bursts of power for short periods of time to kick over your engine and power your boat. The cranking battery sends power to the engine when the ignition switch is activated. Starting batteries are intended to put out a large amount of current for a short period of time.

A cranking battery has more number of lead plates that are thinner and with more surface area to provide the necessary power.


Power or deep cycle marine battery

If you are looking to power onboard electronics and accessories the deep cycle battery is what you’ll need. A deep cycle battery puts out a smaller amount of energy for a long period of time. It can handle long discharge cycles while the engine is off.

A deep cycle battery consists of fewer lead plates that are thicker to provide continuous power output over long periods of time.


Dual purpose or hybrid marine battery

It’s a hybrid battery that has been designed in a way it can be used as both cranking and deep cycle. Dual purpose batteries are sort of a blend of properties of the two. Like many 2-in-1 options, they do not always allow your boat to perform at the same level as two batteries would.

When purchasing a new battery, don’t forget to recycle your old one. Lead acid batteries can be safely completely recycled when done properly in the right facilities.


Battery monitor is your battery’s best friend

Marine batteries lead a pretty tough life and take more abuse than any other battery: pounding waves, seasonal use, long hours without recharge. Investing in a battery monitor solution like Simarine Pico to prolong your baterry’s lifespan just makes sense.

Thousands of batteries are either chronically under-charged or chronically over-charged which makes them kaput. Using Simarine battery monitoring solutions you can:

  • measure input and output currents,
  • know the batteries’ voltages, charged and empty,
  • know the batteries’ temperature.

Information is golden and there is never too much info about your battery. Still, if you find that you are replacing your batteries more frequently than you should be, check and upgrade your electrical system.