diesel engine maintenance and powerboat seamanship 163
Th e second battery, called a domestic or house battery, runs all lights
and navigation electronics. For this you need a deep-cycle battery, which
is capable of being discharged and recharged time and again (whereas
automotive-type starting batteries will weaken if subjected to multiple
deep discharges). House batteries must be capable of handling whatever
electronics you have with plenty of juice to spare.
- Battery connections and ventilation. Clean corrosion from terminals
and make sure connections are tight. Keep batteries in a well-ventilated
compartment outside the cabin. (Batteries can discharge hydrogen and
oxygen with explosive potential, and should never be stored inside a cabin.)
SKIPPER TIP
X A battery selector switch allows power to be drawn from or
recharged to one battery or the other, or both batteries at once.
You must protect your starter battery from deep discharge. In other
words, when you are underway, do not run electronics or lights
with the starter battery. Use the house battery. And do not turn the
battery selector switch from Battery #1 to Battery #2 through the
OFF position while the engine is running. If you do this, you may
very well fry your alternator diodes.SKIPPER TIP
X Don’t forget your underwater appendages. Salt, stray electrical
currents, and incompatible metals pit, corrode, or crumble other
metals if ignored long enough. Install one or more sacrifi cial zincs
next to your propeller, shaft, and through-hulls to make sure corrosion
attacks the zinc instead of these critical components. Once the zinc
disintegrates, the corrosion starts up again. Change out zincs once
a year. If you don’t haul the boat, hire a diver. Spend a bit now to
save a bunch later. Some engines use pencil zincs (long, thin zincs
attached to a threaded screw) that screw into a hole in the engine
body. As with any sacrifi cial zinc, you must change these every so
often. Check the owner’s manual or call your manufacturer to locate
these on your engine.