Join Date: Dec 2002
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This is an aside on battery life:
You mentioned "put a switch in the line that turns the regulator on and off. This is so you can start the engine without the load of the alternator on it"
This suggests a strategy I have used in starting my airplane that has greatly prolonged battery life. I don''t know how your boat electrical starting system is wired, but on my plane, I have a battery switch and and alternator switch; together they are called the master switch. Normal operating procedures call for both switches ON for engine start. As the engine cranks, the sytem voltage is still well under the nominal 14 volts because the alternator won''t put out ''til at least 1200 RPM is reached. Therefore, "sensing" the lower-than-operating-voltage condition, the voltage regulator calls for more current from the battery. It will draw around 5 amps to no avail (and life-shortening to the battery). However, starting the engine on battery-only (analogous to switch you mention above) will effectively take the voltage regulator out of the picture. After, the engine reaches normal operating speed, the Alternator switch is put ON.
Though the 12-volt aircraft batteries are virtually the same as the lead-acid car batteries (slightly higher specific gravity), their life expectancy should at least be that of a car''s. The car battery is in a much more hostile environment than an aircraft battery, yet, the typical 5 year battery doesn''t last more than a couple of years. Perhaps marine batteries have similar challenges.
The best thing I have done to achieve (exceed) the design service life of the battery is not to let them get zapped at anytime and especially during initial charge. If you can do it, add the electrolyte yourself and apply the initial charge after the heat of mixing has dissipated and the solution is only slightly warm. Use a very low charging rate for an overnight charging (not the 0.5 to 2 hours typically done).
Operationally, I use the starting mode described. Also, I ensure the electrical master (and avionics master if you have one) is OFF. Also, all electrical loads, like radios and lights are off before I shut down and rechecked before start up (mostly to protect the radio from starting transients).
With normal battery maintenance, my battery lasted over 8.5 years with the engine operating an average of 150 hours per year (only 100 last 3 years).
Since marine batteries are probably similarly priced to aviation batteries (perhaps more), the increased life really, means a substantial savings.
I hope this helps you all, but of course, you should consult with the manufacturer and comply with any D.O.T., US Coast Guard, or other regulations that may apply concerning the suggestions I have made (this is to cover me).