A State of Readiness: For longer life and greater reliability, marine batteries need care and maintenance all year long.

Originally published in February 2009 issue

By Brett Becker

Nearly every component on a boat enjoys a longer service life when treated to regular maintenance. Engines and drives last longer with regular fluid changes. Upholstery, gelcoat and trailer components all benefit from periodic care and maintenance.

Batteries are another perfectly good example of something that responds well to proper care. In automotive applications, batteries typically see regular use all year long, so maintaining a charge in your car’s battery is often as simple as driving it regularly. Car batteries seldom sit unused for extended periods and aren’t subject to the same kind of pounding as boat batteries. For those reasons, boat batteries are much different from those found in cars.

“Boat batteries are used in more rugged environments, impact, cycling requirements, vibration, possibly even seasonality,” said Gale Kimbrough, technical services manager with Interstate Batteries in Dallas. “They’re made differently, more robust, thicker plates, different paste density than you would have in an automotive application because the automotive batteries require a high output very rapidly and they’re kept in an environment where vibration or impact is not as critical as it is in a boat.

“I have seen people use automotive batteries for boats at different times and they will not last as long because they are not made for that impact and vibration resistance,” he added.

Batteries are at the heart of any boat’s electrical system and will yield a longer service life and provide enhanced reliability—if you look after them. Right now, at least if you live in northern climates, your boat’s batteries are probably sitting somewhere in the cold, clinging to their last few amperes of life. Right now would be a good time to go check on them and bring them back up to snuff.

Winter maintenance is fairly straightforward. Kimbrough suggested removing batteries from your boat and keeping them in your garage or shop. It’s OK to leave them in the boat, he said, but be sure you regularly inspect the batteries for corrosion, connection problems and electrolyte levels. Keep them fully juiced with an automatic battery charger. Trickle chargers are fine, Kimbrough said, as long as they switch off when the battery reaches full charge.

“If it’s automatic, it will automatically decrease that amount of current to a maintenance stage of a few hundred milliamps when it’s operating correctly,” Kimbrough said.

Believe it or not, it’s also important to keep batteries clean. Kimbrough explained.

“Either apply a spray battery cleaner or use a 50/50 baking soda and water mix to neutralize any acid that’s on the battery. Then wash the battery off,” he said. “Keeping it clean is essential too because acid and dirt together on top of the battery, a residue, will allow a current flow from the positive to the negative and can discharge the battery much quicker.”

If the batteries are low on electrolyte—pull the top caps to ensure the plates are submerged in the solution—you likely can get away with using tap water from most municipal water systems, but it’s always a safer bet to use distilled water. Well water is unacceptable because it can contain high levels of iron, Kimbrough said, pointing out that iron-rich water often has an orange tint to it.

“Shallow well-water systems are not good, or anything that’s going to have a high iron content,” he said. “The reason is the chemicals that you might have within that system chemically negate what the battery chemical system is made up of internally. I still prefer and still have distilled water that I use. Of course, I’m a battery man.”

Sometimes, a battery can suffer voltage drops because it has a dead cell. Marine batteries have six cells, which have roughly 2.11 volts per cell. Multiplied by six, that’s what makes it a 12-volt system. A dead cell will drop the total voltage to about 10.5 volts, which isn’t enough to do what you need it to do. It also means you’ll have to replace the battery. Causes for dead cells range from contaminants or vibration to a process called sulfation.

“Sulfation is a term where the sulfuric acid within the electrolyte is going into the plates, and chemically reacting with the plates during discharge,” Kimbrough said. “And so, when you have a discharged battery, you have a large percentage of the sulfuric acid that has become a sulfate in the paste material of the plates. So therefore if you allow it to sit, then the sulfuric acid hardens and becomes a noneffective plate or cell.”

The quickest and most accurate way to tell if you have a dead cell is by using a hydrometer, which measures the specific gravity of the liquid. You can get one at any decent parts store. If one cell is bad or shorted, it will never allow the battery to be any stronger than that weakest cell because each one of those cells are placed within the battery in a series. In other words, the herd is only as strong as the weakest buffalo.

In the event you have to jump-start your boat—and there’s always at least one guy at the ramp with a set of cables in hand, looking for someone to lend a hand—there is a proper way to do it. Connect the cables to the positive terminals first, then the negative cables. On the last negative connection, whether it’s on the boat supplying the juice or the one being jumped, try to find a good ground besides the negative battery terminal.

“If you can find a ground away from the battery on the last connection—away from the battery—it is best, because on the last connection it’s going to offer a spark if you’ve done this correctly,” Kimbrough said. “That last connection, whether it’s the one you’re jumping from or to, you always go to a good ground away from that battery, because if you’re allowing any spark close to that battery, there can be gases, hydrogen and oxygen gases that can explode.”

The conventional wisdom was that the vehicle with the dead battery was the one that required the remote grounding location, but it all comes down to which connection you make last. Battery myths include the age-old story that a battery left on concrete will discharge, but that isn’t true.

“Many years ago, this was true on the old hard-rubber container batteries. Batteries for the last few decades have had polypropylene containers, so you don’t have that situation occur because of the resistance factor of polypropylene compared to old hard rubber,” Kimbrough said. “Now, do I leave them on the concrete typically? No, because they can easily become a stumbling block. But sitting them on concrete does not discharge them or ruin the battery like it could many years ago, back in my dad’s time or my granddad’s time.”

Another myth that simply isn’t true is that marine RV deep-cycle batteries need to be completely discharged occasionally to maintain ampere-hour capability.

“Batteries are made differently today, and much better,” Kimbrough said. “There have been many technological changes in batteries that you do not have to do that at all. In fact, it’s not even good to do that.”

One adage that is still true is that you get what you pay for. Cheap batteries are exactly that. And it shows in how long they last—or don’t last.

“I’ve heard people say many times that I just can’t seem to get more than a year out of my batteries,” Kimbrough said. “I often tell them you have to start with a good quality battery. If you’re expecting long endurance out of them, and keep them charged effectively and clean, they will last much longer if you do that.”

– Brett Becker is a freelance writer for Powerboat.

Contact Information
Interstate Batteries, 12770 Merit Drive, Suite 400, Dallas, TX, 75251, 800-272-6548, www.interstatebatteries.com.

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