How many accessories can you add to an outboard-powered center-console? The answer would seem to be: an endless number. But as more anglers add trolling motors, trim tabs, Power-Poles, radars, autopilots, jackplates, dual multifunction displays, electric downriggers, underwater lights, anchor windlasses and other goodies to their normal electric load of lights, pumps and hydraulics, they amplify the burden on their alternator(s) and batteries.
The impressive expansion of marine electronics and accessories has even prompted outboard manufacturers to install higher-output alternators in their engines. But that's just one small piece of the electrical web.
With all these extra toys comes a learning curve that can be as simple as understanding basic battery and onboard charger functions or as intricate as calculating amp loads and designing the ultimate charging and conditioning system. Let's just start with an overview.
Most outboard boats should carry a 12-volt starting battery and one or more 12-volt deep-cycle batteries. Starting batteries are specifically designed for cranking engines. The outboard's alternator then quickly recharges the battery. If discharged too deeply by other accessories, a starting battery simply won't recharge.
Deep-cycle batteries can withstand deeper discharging, but battery companies warn that excessive discharging - more than 50 percent - can drastically shorten the three- to five-year life of a deep-cycle battery. Some companies, like Optima (888-8OPTIMA; www.optimabatteries.com), make a combination starter and deep-cycle battery that blend the qualities of both.
Optima makes absorbed glass mat (AGM) batteries, which more efficiently accept a charge and usually offer superior run times. Gel-cell batteries can be more forgiving of improper charging systems but are more sensitive to damage from overcharging. AGM and gel-cell batteries come sealed and require no manual maintenance, unlike wet-cell batteries.
Commonly, an angler whose boat hosts a lot of accessories might want a starting or combination starting/deep-cycle battery and a second deep-cycle battery - both hooked to a battery switch and both rechargeable on the fly by the outboard's alternator.
To add a trolling motor to the mix, however, anglers must create a 24- or 36-volt system with two to three deep-cycle batteries connected in series. That system is separate and isolated from the starting and house batteries and is not recharged by the alternator.
Trolling motors draw a fairly substantial amp load (30 or more amps at full speed), especially compared with other electronics like some multifunction displays (1 to 3 amps). They can also interfere electrically with sonar, GPS and other accessories.
To optimize battery usage and life, Daryl Brockman, senior sales application engineer for Optima, has these suggestions:
1. Whenever batteries are in series (for example, the method for combining two 12-volt batteries to equal a 24-volt system) or in parallel (the method for combining two 12-volt batteries into one more powerful 12-volt system), the batteries should be the same size, type and age.
2. Keep batteries as close to fully charged as possible. Charge batteries as soon as you get home from a fishing trip.
3. Choose the proper charger for your battery type, and use it properly.