FORD 2002 Explorer - Manual (Page 272)

BATTERY
Your vehicle is equipped with a
Motorcraft maintenance-free battery
which normally does not require
additional water during its life of
service.
However, for severe usage or in high temperature climates, check the
battery electrolyte level. Refer to the scheduled maintenance guide for
the service interval schedules.
Keep the electrolyte level in each cell up to the “level indicator”.
Do not overfill the battery cells.
If the electrolyte level in the battery is low, you can add plain tap water
to the battery, as long as you do not use hard water (water with a high
mineral or alkali content). If possible, however, try to only fill the battery
cells with distilled water. If the battery needs water often, have the
charging system checked.
If your battery has a cover/shield, make sure it is reinstalled
after the battery has been cleaned or replaced.
For longer, trouble-free operation, keep the top of the battery clean and
dry. Also, make certain the battery cables are always tightly fastened to
the battery terminals.
If you see any corrosion on the battery or terminals, remove the cables
from the terminals and clean with a wire brush. You can neutralize the
acid with a solution of baking soda and water.
Batteries normally produce explosive gases which can cause
personal injury. Therefore, do not allow flames, sparks or lighted
substances to come near the battery. When working near the battery,
always shield your face and protect your eyes. Always provide proper
ventilation.
Maintenance and care
272