Honda 2003 Civic Si Owner's Manual page 183

Battery
Check the condition of your car's
battery monthly. You should check
the color of the test indicator window,
and for corrosion on the terminals.
184
Maintenance
TEST INDICATOR WINDOW
Check the battery condition by
looking at the test indicator window
on the battery.
The label on the battery explains the
test indicator's colors.
Check the battery terminals for
corrosion (a white or yellowish
powder). To remove it, cover the
terminals with a solution of baking
soda and water. It will bubble up and
turn brown. When this stops, wash it
off with plain water. Dry off the
battery with a cloth or paper towel.
Coat the terminals with grease to
help prevent future corrosion.
WARNING: Battery posts,
terminals, and related accessories
contain lead and lead compounds.
Wash hands after handling.