Marine Batteries: Deep Cycle or Cranking?

Buying a marine battery is an important choice. When you’re out on the water, you need to be able to rely on your battery power to keep essential systems running, as well as to start the engine, which can occur several times during a day on the lake.

There are two major classifications for marine batteries, and each has its own specialty:

Cranking Batteries

In order to get the burst of power needed to start an engine, a cranking battery needs to deliver a large current for a short amount of time--often 75-400 amps for anywhere between 5 and 15 seconds, depending on the boat’s engine. Lead acid cranking batteries have more numerous, thinner lead plates than a deep cycle battery. This increased surface area allows for the flow of higher amps through the battery. However, if cranking batteries are frequently discharged to the same level as deep cycle batteries (which would happen if you also use cranking batteries for trolling and keeping systems going throughout the day), their lifespan is greatly reduced.

Deep Cycle Batteries

Deep cycle batteries are made to be able to frequently discharge and recharge. They’re also built to give a lower amount of energy for a longer period of time. With thicker lead plates and reduced surface area, they’re sturdy and made to discharge down to 20% regularly. Deep cycle batteries are great for the many energy needs of your boat after you’ve already started it, including navigation, lights, music, radar, etc. However, if they’re asked to provide the starting charge for an engine, they won’t always perform. It will depend on the battery's cranking amps rating (or the cold cranking amps), which is usually fairly low for deep cycle batteries. 

Buying Marine Batteries

These batteries are complementary in function, and neither can perform the other’s job as well. Most boats are equipped with two different batteries, one for each purpose. However, there are also dual purpose marine batteries on the market that find a middle ground between the two different types.

Learn more about the ratings for marine batteries here, and browse our recommended offerings for RV and marine batteries here. Here at MK Battery, we offer only the best in quality, whatever the purpose of their battery. Contact us to learn more.