Whether charging or discharging, batteries suffer over time from a process called sulfation. Sulfation causes crystals to build up and coat the battery's plates, diminishing its effectiveness and life.
Some chargers primarily recharge batteries; others also condition batteries to remove some sulfation. There are also systems that fully recondition batteries, especially during periods of long storage.
"One of the main things I hear out there when I talk to consumers is they think all chargers are at parity," says Joe Brown, brand manager for Minn Kota (800-227-6433; www.minnkotamotors.com), which makes its own line of chargers. "They think they can use an old single-stage car charger, but that will kill a battery with its high voltage over time."
Proper chargers offer a variety of profiles that match specific battery types. These chargers also feature at least a three-stage process: bulk, absorption and float/maintain. During bulk, a constant current fills the battery like you'd fill your gas tank, says Jerry Demirjian, senior vice president for ProMariner (603-433-4440; www.promariner.com), which makes chargers and marine accessories. Absorption is a constant-voltage mode. Float/maintain holds the battery at a full charge. ProMariner's new digital products include a fourth periodic and automatic battery-health stage, Demirjian says.
The time it takes to recover a battery depends on the battery and the charger's amperage. A 100-amp-hour battery discharged to 50 amps takes five to seven hours to recharge with a 10-amp charger.
During winter or periods of long storage, products like PulseTech's (800-580-7554; www.pulsetech.com) Xtreme Charge use pulse charging to dissolve sulfation and renew batteries. To continually condition a battery while it's in use, PulseTech's PowerPulse - at $52.95 for the 12-volt version - connects to the battery and runs off the onboard charger or alternator.
Most onboard chargers work only when plugged into an AC circuit at the dock or at home. But at least two products - DC alternator chargers made by several manufacturers, including Minn Kota, and ProMariner's new ProIsoCharge ($149 to $349, available by the end of 2010) - can help anglers spend more time on the water. The DC charger uses current from an outboard's alternator to charge trolling batteries. But Minn Kota's Brown adds a caveat: This product really best helps tournament anglers who run long distances between drops, allowing the alternator enough time to make a difference.
The zero-volt-loss ProIsoCharge uses digital software to manage the health of all connected batteries by gauging and properly distributing the alternator's charge. ProIsoCharge replaces a traditional battery isolator (which allows starting and house batteries to charge and discharge independently regardless of where the battery switch is set). Traditional diode-based isolators can help protect a starting battery, but they lose voltage during charging.
While many more variations and issues exist within the battery and charger markets, here's the take-home message from manufacturers contacted: Learn about and manage your onboard power needs. This ain't your father's fishin' boat.