Porsche 911 CARRERA - 2003 Manual page 216

Battery care
[>
Ensure that battery is securely mounted.
[>
Keep terminals and connections clean and
properly tightened.
Corrosion can be prevented by coating the
terminals and connections with petroleum jelly
or silicone spray.
[>
Ensure that vent caps are securely tightened
to prevent spillage.
216
Practical Tips, Emergency Service
Checking the electrolyte fluid level
Generally, the electrolyte level must be checked
more often in summer than in the winter, and
more often when driving long distances.
[>
When adding water, use only clean vessels.
In no case may alcohol (e.g. window cleaner
residues) be permitted to enter the battery.
[> Unscrew and open the filler vent caps of each
cell.
With the car horizontal, the fluid level should
meet the indicator mark in each cell.
[> If necessary, top up with distilled water.
Do not use
acid.
Only fill up to the mark, otherwise the electro-
lyte will overflow when the battery is being
charged and cause damage.
Battery charging
Automotive batteries loose their efficiency when
not in use.
The charge available in your battery can be
measured with a battery hydrometer.
We recommend that the battery voltage be
tested by your Porsche dealer who has the ap-
propriate equipment.
If the car is not driven for prolonged periods,
the battery must be charged at least every 6
weeks.
A discharged battery allows rapid formation of
sulfates, leading to premature deterioration of
the plates.