Volkswagen Jetta / Bora: Electrical System Manual - part 2

Checking battery

WARNING

Danger of injury! Observe warning notices and safety regula‐

tions 

⇒ page 2

 !

Caution

To prevent damage to the battery and vehicle, the following

should be observed concerning types of battery 

⇒ page 1

 .

2.1

Procedure when checking the battery

Carry out procedure in sequence as follows:
1.

Visual check 

⇒ page 5

 .

2.

Checking battery with a magic eye 

⇒ page 6

 or checking

a low maintenance battery 

⇒ page 7

 .

3.

Check no load voltage of battery 

⇒ page 10

 .

4.

Perform a battery load test using battery tester with printer

-VAS 5097 A- 

⇒ page 12

 .

2.2

Visual check

WARNING

Danger of injury! Observe warning notices and safety regula‐

tions 

⇒ page 2

 !

It is essential first to check the external condition, the terminals of

the battery and that the battery is seated securely visually before

performing more extensive tests.

Caution

♦ The battery will be damaged if the battery is not secured

correctly.

♦ Vibrations shorten the life of the battery, there is a danger

of an explosion, the cell plates may be damaged and the

securing plate may damage the battery housing.

♦ Check battery is securely seated, if necessary tighten se‐

curing bolt to specified torque setting. 

⇒ page 36

♦ Whether the battery housing is damaged: Check whether the

battery housing is damaged. Electrolyte can leak out if the

housing is damaged. If battery acid leaks out, serious damage

to the vehicle could be caused. Treat areas of the vehicle af‐

fected by leaked battery acid immediately with acid neutraliser

or a soap solution.

♦ Whether the battery terminals (battery wiring/cable connec‐

tions) are damaged. Check whether the battery terminals (bat‐

tery wire connections) are damaged. The necessary contact

at the terminal clamps cannot be guaranteed if the terminals

are damaged. When connecting clamps to the terminals, tight‐

Jetta 2005 ➤ , Bora 2006 ➤

2. Checking battery    

5

If the clamps are not correctly seated and tightened, the wiring

could burn, which could result in electrical system malfunc‐

tions. Which will cause malfunctions in the electrical system.

Therefore it can no longer be guaranteed that the vehicle will

function correctly.

2.3

Checking battery with magic eye

WARNING

Danger of injury! Observe warning notices and safety regula‐

tions 

⇒ page 2

 !

The magic eye (condition indicator) provides information on the

electrolyte level and condition (charge state) of the battery.
Batteries with a magic eye are produced in two versions:
♦ Low maintenance 

⇒ page 1

♦ Maintenance-free 

⇒ page 1

Note

Because the magic eye is located in only one cell, the display

applies only to this cell. An exact determination of battery's con‐

dition is only possible through a load test 

⇒ page 12

 .

– Before performing a visual check, tap the magic eye lightly and

carefully with the handle of a screwdriver.

The air bubbles, which can influence the display, will dissipate

when doing this. The colour display of the magic eye will therefore

be more accurate.

Note

♦

Air bubbles can form below the magic eye particularly when

the battery is being charged, including during normal vehicle

operation. These falsify the colour display of the magic eye.

♦

The magic eye can be located at various positions on the bat‐

tery.

Three different colour displays are possible:
♦ “Green”, battery is charged sufficiently.
♦ “Black”, Battery partly discharged, charge state < 65 % or

completely discharged.

♦ “Colourless or yellow”, battery must be renewed.

Note

♦

Charging battery with battery charger -VAS 5095 A-

⇒ page 15

 .

♦

Charging battery with battery charger -VAS 5900-

⇒ page 19

 .

Jetta 2005 ➤ , Bora 2006 ➤

6

Checking low maintenance battery

WARNING

Danger of injury! Observe warning notices and safety regula‐

tions 

⇒ page 2

 !

This battery is “low maintenance” this means the electrolyte level

must be checked and occasionally topped-up with distilled water

as required.

2.4.1

Checking electrolyte level of battery

Check electrolyte level on housing:
– Check electrolyte level via -min./ max.- marking on the battery

housing.

The electrolyte level is OK when the fluid level is at the max.

marking.
If the electrolyte level is below the -max.- marking:
– Replenished with distilled water 

⇒ page 7

 .

Check electrolyte level in the cells:
– Switch off the ignition and all electrical consumers.
– If fitted, remove the protective foil on the cell sealing plug.

Note

The foil with the warning notices must remain on the battery.

– Remove cell sealing plugs.
– Check the electrolyte level of the battery cells.

The electrolyte level is OK when the fluid level -1- is the same

height as the plastic peg.

Note

The plastic peg corresponds to the max. marking.

If electrolyte level is OK:
– Check the cell sealing plugs and the O-ring seals for damage.

Damaged parts must be replaced.

– Seal the cells with the cell sealing plugs.
If the electrolyte level is under the plastic peg:
– Replenished with distilled water 

⇒ page 7

 .

2.4.2

Topping up with distilled water

Special tools and workshop equipment required

Jetta 2005 ➤ , Bora 2006 ➤

2. Checking battery    

7

Caution

♦ When filling up with undistilled water or electrolyte the bat‐

tery will be damaged. Top up with distilled water only.

♦ The battery may be damaged when the cells are overfilled.

When topping up use only the battery filling bottle -VAS

5045/- . The construction of the filler neck prevents an

overfilling of the battery cells.

– Check the electrolyte level of the battery 

⇒ page 7

 .

– Switch off the ignition and all electrical consumers.
– If fitted, remove the protective foil on the cell sealing plug.

Note

The foil with the warning notices must remain on the battery.

– Remove cell sealing plugs.
– Replenish with distilled water using battery filling bottle -VAS

5045/- . When the max. level is reached the flow is interrupted

automatically.

– Check the cell sealing plugs and the O-ring seals for damage.

Damaged parts must be replaced.

– Seal the cells with the cell sealing plugs.
– Check no load voltage of battery 

⇒ page 10

 .

– Perform battery load/discharge test 

⇒ page 12

 .

2.4.3

Check electrolyte density

Special tools and workshop equipment required

Jetta 2005 ➤ , Bora 2006 ➤

8