AUDI A4 2000 B5 / 1.G Battery Workshop Manual

27-1


Battery
The battery is one of the most important
electrical components in the vehicle. If it
functions properly, the battery will make a
significant contribution to customer satisfaction.
To ensure a long service life, the battery must be
checked, serviced and maintained as described
in this section.
In addition to starting the engine, the battery has
additional functions as a buffer and supplier of
electrical power for the entire vehicle electrical
system.
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27-2


Warnings and safety precautions for lead-acid batteries
1 - Follow the recommendations on the battery, in this Repair Manual
and in the Owners Manual.
2 - Danger of acid burns:
Battery acid is extremely caustic, therefore wear protective gloves
and eye protection.
Do not tip battery. Acid may escape from battery vents.
3 - Keep open flame, sparks, unenclosed light bulbs and lit smoking
materials away from battery.
Guard against creating sparks when working with cables and
electrical equipment.
- Avoid short-circuits.
4 - Wear eye protection
5 - Keep children away from acid and batteries.
6 - Proper disposal:
Waste batteries must be brought to appropriate waste disposal site.
Dispose of old batteries in compliance with applicable Federal,
State and local laws regarding hazardous waste disposal.
7 - Never discard old batteries in the household trash!
8 - Explosive hazard:
Highly explosive gas is produced when batteries are charged.
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27-3

Battery handling instructions


Notes:

Battery terminals should no longer be coated
with grease.
To avoid damage to the battery case, place the
cable clamps on the terminals by hand without
using force.
The battery terminal clamp tightening torque is
6 Nm (53 in. lb).
Once the battery is reconnected, check and
activate the vehicle's electrical equipment
(radio, clock, comfort and convenience
features, etc.) as described in the Repair
Manual or the Owner's Manual.
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27-4

Battery, removing and installing


CAUTION!

Disconnect the battery Ground (GND) strap
before working on the electrical system.

Notes:

Before disconnecting the battery, determine the
correct coding for the anti-theft radio.
Once the battery is reconnected, check and
activate the vehicle's electrical equipment
(radio, clock, comfort and convenience
features, etc.) as described in the Repair
Manual or the Owner's Manual.

Removing

- Disconnect battery Ground (GND) strap from negative terminal by
loosening nut -1-.
Tightening torque: 6 Nm (53 in. lb)
- Disconnect battery positive cable from positive terminal by loosening
nut -2-.
Tightening torque: 6 Nm (53 in. lb)
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27-5


Installing
Notes: - Remove bolt -3- and remove hold-down clamp -2-.
Tightening torque: 15 Nm (11 ft lb)
- Lift battery -1- out of battery tray.
The newest generation of batteries is equipped with a central gas vent
and flame trap by means of a "baffle." Function: the gas produced during charging escapes at one place
through an opening in the top of the cover. The flame trap (which
prevents the flammable gas located in the battery from igniting) is also
integrated in this unit. For proper venting of the battery via the diffuser and the hose, it is
important that the hose attached to the central gas vent does not
become pinched off during installation. The diffuser consists of a small round glass fiber mat having a
diameter of approximately 15 mm and a thickness of 2 mm. It
functions similar to a valve, i.e., it allows the gas formed in the battery
to flow out.
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27-6

Note:

When installing the battery (if the battery has a central gas vent), make
absolutely certain that the hose is not pinched off. This allows the battery
be freely vented via the diffuser and the hose. If the battery does not have
a hose, make sure that the opening on the top of the battery's cover is not
plugged.
Make sure battery is securely mounted
If the battery is not secured properly, there is a risk that the following
might occur: - Install in reverse order of removal.
Shortened service life due to damage caused by vibrationBattery cell and plate damageDamage to battery case by the hold-down clamp (possible release of
electrolyte resulting in costly damage). Poor collision safety
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27-7

Visual inspection


WARNING!

When charging, measuring the voltage or
load testing a battery, the cell caps must
always be screwed in tightly.
Before performing tests such as no-load voltage,
specific gravity or the battery load tests, a visual
check should be made of the battery.

The purpose of this check is to determine

If the case of the battery has been damaged.
Damage to the case can cause acid to leak.
If the terminals have been damaged. Damaged
terminals make it impossible to assure a good
contact at the terminal. This can lead to a cable
fire and damage to the electrical system.
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27-8

Electrolyte level, checking


CAUTION!

To ensure that the various battery cover
systems do not leak, the original cell caps
that come with the battery must always be
screwed in. If they are lost or damaged, use
only genuine cell caps for the same model
battery. The cell caps must be equipped with
an O-ring seal.

Notes:

Maintaining the correct electrolyte level is
important for long battery life.
If the battery has visible minimum and
maximum lines on the case, the electrolyte level
can be checked from outside the battery.
The electrolyte level must be between the
minimum and maximum lines.
If the external minimum and maximum lines are
hard to see or if it is difficult to see the
electrolyte level due to opacity of the battery
case, the cell caps will have to be removed.
After that it will be possible to visually check the
electrolyte level from the interior of the battery.
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The electrolyte level must reach the internal
electrolyte level indicator (lip of plastic flange).
This corresponds to the external maximum line
on the battery case.
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27-9

Electrolyte level too low

Special tools, test equipment and auxiliary
items
VAS5045 battery cell filler

Note:
If the electrolyte level is too low, the plates will
dry out causing a loss of capacity (power loss) in
the battery. If the plates are not surrounded by
electrolyte (sulfuric acid), the plates, plate straps
and the cell connectors will corrode. The result of
this corrosion is that battery function can no
longer be assured. The battery is made useless.

Notes: - If electrolyte level is too low, add distilled water up to maximum mark
using VAS5045 battery cell filler.
The design of the filler nozzle of the VAS5045 battery cell filler
prevents overfilling the battery cell and loss of battery acid. When the
maximum fill level is reached, the flow of distilled water into the battery
cell is stopped. To avoid contaminating the electrolyte, add only distilled water to the
battery (contaminated water will lead to increased self-discharge).
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