Your boat's battery is just as important as the battery in your car, as that battery starts the boat's engine and runs many of its components and devices, including the navigational equipment, the lights of the boat, and so on. This is why you want to ensure you choose the right battery for your boat in particular. Note a few details to remember when shopping for a new marine battery, and this can help you to find one that is the right size and which delivers enough power for your boat and equipment.
A battery group refers to the actual size of the battery, and note that this doesn't indicate the battery's power, but its physical dimensions. These dimensions may vary just slightly within each group, to allow for posts, handles, and other obstructions, but it's good to check your boat's owner's manual and find the battery group that is recommended for your boat's battery compartment.
A battery's discharge or type refers to the power it can deliver. Short discharge batteries are meant to deliver one strong burst of power to start the boat's engine, but may not be good for prolonged or deep discharges, meaning the use of high-powered navigation system, large running lights, and other such electrical equipment. Deep cycle batteries are meant for these long-term discharges and can provide more continuous power when you're on the water. If your boat has a large engine and needs lots of starting power, and also has high-powered electrical equipment to operate while boating, choose a hybrid or dual-purpose battery type.
Cold cranking amps
When choosing a battery for your vehicle, you may need lots of cold cranking amps, meaning more power during cold weather. However, if you don't tend to take your boat on the water when the weather is cold, this may be an unnecessary expense for a marine battery. You might choose a battery with a larger reserve capacity, which refers to how much power the battery will continue to produce even as it's dying out. The more reserve capacity, the longer you can operate your navigational systems with a damaged or dying battery.
Even if a battery sits on a shelf, it will eventually lose power, as the chemicals inside change and react over time. Note the date of manufacture of a battery when making a selection and opt for the newest one available, rather than thinking that all marine batteries for sale were made at the same time and will last as long as the next.