First thing that anglers should learn, especially those who depend heavily upon electric trolling motors while moving from one spot to another: There's a big difference between an automotive and a marine battery.
Probably most of us at one time or another have used our car, truck, or RV battery to supply power for an electric trolling motor and then cussed when the automotive unit failed to hold a charge following two or three outings.
The reason is automotive batteries are designed to supply a short burst of cranking power at approximately 300 to 500 amperes until an alternator can take over. They are simply more suited for starting power than for staying power.
Trolling motors pull 5 to 25 amperes whenever they're used to move your boat. As a result, after hours of fishing, the power is nearly exhausted.
Therefore, an important feature of batteries used to supply all the power to operate a trolling motor is its ability to come back.
A good marine battery is designed to be charged and recharged again and again to full power, whereas an automotive battery is designed for an entirely different purpose.
Marine battery plates are 15 percent thicker and the active material denser than those used in an automotive battery.
Because an automotive car battery needs a fast energy flow, its plates are thin and the active material is quite porous. Unfortunately, this also causes car or truck batteries to deteriorate rapidly when repeatedly discharged since the active material drops from the grids, eventually destroying the battery.
Marine battery plates are also reinforced with an interlocking web of glass fibers to hold the active material on for extra durability.
Like automotive batteries, marine units come in several sizes. When selecting a marine battery, the first thing you should do is decide what your average discharge rate will be.
For example, an electric trolling motor will average 10 to 15 amps at medium speed.
Assuming that you'd average 12 amps with our trolling motor while on the water, how long could we expect a small and a large marine battery to continue delivering power?
A small deep-cycle battery would probably provide about 5.3 hours of continuous power, while a larger one will probably perform continuously for about 7 hours.
Both automotive and marine batteries will give you longer, more dependable and trouble-free service with proper care.
To get longer life from a marine battery, you might follow these simple maintenance procedures:
1. Check the level of electrolyte frequently and add tap water to cover the plates. Avoid overfilling. If the electrolyte level drops below the top of the plates causing them to dry out, capacity of the battery is significantly reduced.
2. Keep terminal connections and cables free from corrosion which, if it builds up, will reduce or even block the flow of power. Clean battery terminals with a wire brush and then coat them with a heavy-bodied mineral grease.
3. Fully charge your marine battery after each use. If the battery is allowed to stand discharged for long periods of time or in a partially discharged state, the plates harden to a point where it is difficult to recharge the battery completely.
4. When not in use, store your marine battery--fully charged--in a cool, dry place. If the battery must be stored for several months, you should recharge it every 60-90 days. Choose a battery charger carefully. One that is too small will require too much time to fully recharge the unit. A 10-amp charger will do the job twice as fast as a 5-amp.
5. And, finally, don't overcharge your marine battery. Prolonged periods of overcharging will cause damage by destroying the plates and "boiling off" the water. Use a hydrometer for accurately determining the percentage of charge in the battery.
Copyright (c) 1996 Herb Allen. All rights reserved.
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