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What
is the open-circuit voltage of a 12-volt battery, and how can you test
for it? V.L., via e-mail
Open-circuit
voltage is what is measured when a battery is not delivering or receiving
power. For a fully charged 12-volt battery, the reading should be 12.66
volts, or 2.11 volts per cell.
To check
the open-circuit voltage of your battery, first disconnect the battery
cables so that no power is coming in or going out. Set your multimeter
to read “DC volts” (for meters without auto ranging, set the
scale to 20 volts), and touch the red (positive) probe to the positive
battery terminal and the black (negative) probe to the negative terminal
as shown here. If the reading is below 12.66 and the battery has been
fully charged, one or more cells may be damaged or may have excessive
sulfite buildup on its plates. A hydrometer test for each cell will determine
which, if any, is bad. Placing the battery under an equalizing charge
can remove sulfite buildup on the plates. Check with your battery manufacturer
for the correct way to perform this procedure.
While
getting ready to transport our tender’s outboard, it slipped into
the water. We retrieved it quickly but are worried about possible damage
from the saltwater submersion. What is the procedure for cleaning it up?
J.H., via e-mail
First,
rinse the outside of the outboard with clean, fresh water. Then remove
the cover and rinse off the engine. If you have access to compressed air,
blow the water off all exterior surfaces; if not, thoroughly wipe down
the engine.
Now
use the compressed air—in this case, canned air will do—to
blow off water and residue from around the plug(s). Disconnect the plug
wire(s) by twisting the boot back and forth while pulling; pulling on
the wire instead of the boot may cause internal damage to the wire. If
the plug is difficult to remove, apply penetrating oil—Liquid Wrench
or WD-40—around the plug threads, and let it soak for about ten
minutes.
Remove
the plug(s) with an appropriate socket wrench. Upon reassembly you should
replace them with new ones of the correct heat range and gap. Drain as
much water as possible from the power head by placing the outboard in
a horizontal position and manually rotating the flywheel with the spark
plug hole(s) facing downward. Next, pour rubbing alcohol into the carburetor
throat(s) to displace any water in the intake system. Manually rotate
the flywheel at least one full turn, then position the engine so you can
pour more rubbing alcohol into the spark plug hole(s). Manually rotate
the flywheel another full turn. You can now install the new spark plug(s).
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