Fishing & Boating in the Northwoods

Types of Marine Batteries – 12 Volt

onboard boat charger

This article will explain the different types of marine batteries you may have or need onboard your boat.

One Final Outing

Usually, by the end of October, many of the lakes have “turned over” for the winter. Morning steam rising from the water indicates that the heat energy stored in the lake from the long hours of summer daylight is beginning to return once again to the atmosphere as the lake water begins its annual slumber and ultimate renewal.

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There is perhaps still a little time left for one final outing. Most of you – if not all – have taken your boats out of the water and gotten them cleaned out, “winterized” and ready for next spring’s trek back to your favorite fishing spots. You take very good care of your boats, motors, poles, reels, and other gear inside the boat. But have you really taken the time to consider one of the most important pieces of equipment that you have on board – your batteries?

Most of us take our boat batteries for granted, in much the same manner as we do our car batteries. I used to do that. In fact, I had a car that sat in the warmth of the garage all winter. I thought that an occasional blast from a charger would be enough to do the trick. Boy, was I wrong. And the result was a new battery about every other year – until, after a lecture from my mechanic, I got a little bit smarter about batteries.

So, here are a few things to keep in mind. For starters, there are two basic types of 12-volt batteries:

Cranking or Starting Batteries

These are designed specifically to start your main engine. They are made with thinner and more numerous lead plates inside, allowing for more surface area and thereby providing the quick and massive amounts of energy required for tough starting jobs. While the motor is running, the alternator inside will easily and quickly replenish the used energy.

If your boat is powered by a newer model outboard with sophisticated computers, pumps and sensors, you definitely want to make certain you have enough starting power. It’s a good idea to check your owner’s manual for the recommended MCA (Marine Cranking Amps: a measurement of the number of amps a battery can deliver at 0 ° F for 30 seconds and not drop below 7.2 volts) rating before shopping for a battery; always choose one with a rating equal to or greater than the recommended value.

Deep-Cycle Batteries

These are designed to power on-board electrical accessories such as trolling motors, fish-finders, GPS, radios and the like. In general, these batteries use energy at a much slower rate and often don’t get re-charged until the end of the day.

This deeper and more strenuous discharge is hard on a battery and requires a different design type. The result is a battery with fewer, but much thicker lead plates that will withstand the deep cycling. Deep-cycle batteries can withstand the rigors of several hundred discharge/recharge cycles. Cranking batteries cannot. It’s important to understand that, because of their design differences, substituting one battery type for another is not a good idea.

Using a cranking battery to power a trolling motor will cause the battery to overheat and fail. Besides leaving you without power in a moment of need, purchasing a new battery will definitely be in your future.

Similarly, substituting a deep-cycle battery for a cranking battery will likely not provide the power needed to start your outboard. This could possibly leave you stranded a long way from your dock. As it turns out, the design strengths of each battery type also are their weaknesses in opposite applications.

Having said that, there are dual-purpose batteries that can perform both these functions – to some extent – also are available. Keep in mind however, they will not supply the same starting power as a true cranking battery, nor will they provide the same number of discharge/recharge cycles as a dedicated deep-cycle battery.

Stores such as BassPro, Cabela’s and even Farm & Fleet offer marine batteries for sale. You can also check with local marina or even a nearby auto supply store.

If I have whetted your appetite for more battery knowledge, there are several additional battery articles to assist you…

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R. Karl

Angler, Author & Epicure

Fishing since the age of eight.  Seriously writing since the age of 16. Chef and foodie from the age of 22 years… and counting. So much to learn and so little time. I have enjoyed every minute of it all.  Whether on the water (where I like it best), in the kitchen, or at the keyboard, churning out content, I feel like I have found my place.  I am sharing it with you in the hope that some of what I love to do will rub off on you. I hope to see you On the Lake!

R. Karl