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May 30, 2008

Power Trip

Pick the right batteries and keep them charged to avoid down time.

If the best sound in our sport is a reel drag screaming from the strain of a big fish, then the worst sound is the anemic groan of an engine that won't start because of a dead battery. Of course, timing is everything. Batteries always seem to die when your boat is blocking the ramp on the only Saturday you have free during the hottest bite of the season. There is a simple remedy, however. By choosing the right batteries for your power needs and maintaining them properly, you'll be happily listening to drags going off rather than moaning at the dock.

Like landlubbers, anglers have become reliant on a steady source of electricity. This dependence is offset in part by sophisticated outboard and inboard engines that produce more amperage. But those engines have computerized sensors and controls that need a good jolt to start before the alternator can take over. On top of that, we're loading boats to the gunwales with current-zapping gear.

Consider the average mid-sized center console with at least one plotter/sonar display and VHF radio. Add redundant livewell and washdown pumps, electric downriggers and kite reels plus a console power port to plug in a cell phone or iPod. Throw in a stereo system with enough bass to blast Bimini. Add it all up, and that's a lot of juice.

Multiple Options
Marine batteries are categorized by type and chemistry. The different types are starting, deep-cycle and dual-purpose. The chemistry distinctions consist of flooded or wet-cell, absorbed-glass mat (AGM) and gel systems. All use positive and negative plates made from lead alloys and sulfuric-acid electrolytes to generate and store electrical energy. Picking the most suitable one depends on the application, power requirements and cost.

"The difference between starting and deep-cycle batteries is like comparing sprinters and marathon runners," says Tom Burden, a technical advisor with West Marine. "One is good for short, fast bursts of more amps to crank the starter of your boat engine and recharge quickly. The other does well as a steady house battery for other electrical needs when there's no charging source. It won't generate as many cranking amps, but it does store energy well and can be drawn down and recharged hundreds of times. The third option, dual-purpose, is a good choice for fish boats using a single battery or two identical banks since they'll last longer and are more ruggedly built."

Burden recommends replacing batteries with the same size and type if the previous one was working effectively. If it wasn't powerful enough or a longer life cycle is needed, switch to a bigger group battery. Jumping from a group-24 to group-27 battery adds cranking amps because of additional lead plates, so the system operates more efficiently.  Bear in mind, battery group size determines the actual size and weight of the battery. If you decide to make the jump to a larger group number, make sure you have enough space for it, and be sure your mounting system is adequate to hold a larger, heavier battery.

"Always stick with one battery chemistry, or the charging ability might be diminished," he adds. "And it's best not to mix old and new batteries. The old ones pull the new ones down to the lower level."

Finally, check out the discharge cycle when buying a deep-cycle battery. That's the number of times it can be recharged before it starts failing. Deep-cycle batteries don't mind being discharged fully then recharged, but there is a limit to how many times it can be done.

Pluses and Minuses
Flooded-cell batteries with liquid sulfuric-acid electrolyte dominate the market. They are the most economical and come in all three configurations. They also tolerate over-charging since the case is vented to allow potentially explosive hydrogen vapors to escape. This same feature, however, requires upright mounting and topping the cells off periodically with distilled water. The electrolyte is more susceptible to cold weather, plus the design's thinner plates don't handle excessive vibration.

Gel batteries are made with two kinds of acid, pure water and silica. Although initial cost is higher, maintenance-free gels have the longest life of any battery type. With only moderate cranking amps versus slow self-discharge, gels are best suited as house batteries. Finally, for dual-purpose, starting and accessory power, absorbed-glass-mat batteries are winning plenty of converts.

"AGM batteries are quickly becoming the marine battery of choice because of their rugged construction, performance and longevity," says Bill Walter, an electrical engineer with Sear's Diehard Batteries. "The absorbed-fiberglass mats are compressed to hold the electrolytes like a sponge, so there's no excess acid to slosh around and spill. Our Platinum AGMs use pure lead for the grids, and the entire case is sealed and maintenance-free. But the best attribute for anglers is the extremely vibration-resistant design. It'll take the pounding of rough water."

In addition to their higher cost (nearly double a comparable flooded deep-cycle), AGM batteries can be damaged during recharging. Although the resulting oxygen and hydrogen gases mainly recombine to form water, a sealed one-way valve allows venting. Too much charging can boil the water, resulting in premature failure. A voltage-clamping charger that automatically shuts off once the battery is back to full charge will prevent this problem.

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Security by the Numbers
When buying 12-volt replacement batteries, there are several technical measurements to consider. Marine cranking amps (MCA) are the number of amps a battery will produce for 30 seconds at 32 degrees F while maintaining voltage above 7.2 volts. Cold cranking amps produce the same reading at 0 degrees. Batteries are also rated by amp hours and reserve minutes, or the time they'll last under specific loads. A 200Ah battery will run a 10-amp load for 20 hours. The time a battery can maintain a 25-amp load before dropping below 10.5 volts is the reserve-minute rating.

To make sure your needs are met by the battery you select, add the amperage draw of all the accessories you'll be using such as GPS, radios, fish finders and stereo systems. Don't forget livewell pumps. You'll get an accurate tally of the total demand you are making on your battery. Compare that total to the battery's amp-hour rating. If the battery capacity is less than the total of your accessories, reconsider the size of battery you select.

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Surefire Stealth
Electric trolling motors are great tools to use when targeting shallow depths orholding a stationary position, but once the juice runs out, they become useless bow ornaments. The Bass Maxx II system ($295) from Wells Marine Technologies ensures that doesn't happen. This maintenance-free device automatically aligns trolling batteries in parallel and charges them off the main-engine alternator. The starting battery is isolated so it stays fully charged. If it should drain unexpectedly, an emergency switch allows the trolling-motor batteries to start the engine. The Bass Maxx II works with 12-, 24- or 36-volt systems. wellsmarinetech.com