Volkswagen Golf / Golf GTI / Jetta. Manual — part 1070

27-23

Specific gravity, checking

WARNING!

Prior to handling or servicing batteries, read,
understand and observe the Warning and
Safety Measures for lead-acid batteries

Page 27-4

.

Dispose of electrolyte (sulfuric acid)
properly! Waste electrolyte must only be
disposed of in appropriate waste disposal
sites. Refer to local regulations pertaining to
electrolyte disposal.

The following notes and procedures must be
followed to ensure correct measurements.

Special tools and auxiliary items needed

Commercially available hydrometer

Shop rags

Battery, checking

13/2/2005

27-24

Notes:

Checking specific gravity shortly after topping

up with distilled water will result in erroneous
readings. Charge battery after topping up with
distilled water, then check specific gravity.

Minimum battery temperature of 10 C (50

F) is required when carrying out specific gravity
tests.

Specific gravity of all cells must be checked.

CAUTION!

Before beginning repairs on the electrical
system

Switch off all electrical consumers.

Switch ignition off and remove ignition
key.

- Remove all battery cell caps.

- Dip end of hydrometer into cell and extract

sufficient electrolyte to allow indicator float to
swim freely (the greater the electrolyte density in
kg/dm

3

, the higher the indicator float position).

Note each cell's specific gravity reading from
float -arrow-. Repeat sequence until all cells are
checked.

Battery, checking

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27-25

- Review noted values and compare with values

in table below:

Charge condition
(normal climate)

Specific gravity in

kg/dm

3

Discharged

1.15

Half charged

1.22

Fully charged

1.28

Electrolyte density must be at least

1.24kg/dm

3

- If specific density is too low, charge battery and

recheck specific density afterwards.

Electrolyte density must not vary more than

0.04kg/dm

3

between cells.

Examples of unacceptable variations in

specific gravity:

Specific gravity variations per cell in kg/dm

3

Cell
Number:

1

2

3

4

5

6

Example
1:

1.24 1.25 1.25 1.10 1.24 1.25

Example
2:

1.26 1.26 1.25 1.14 1.18 1.24

Example 1: Specific gravity in cell 4 (1.10) is too

low.

Example 2: Specific gravity in cells 4 (1.10) and 5

(1.18) are too low and variation between cells
exceeds 0.04kg/dm

3

.

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If specific gravity specifications are not met,

replace battery.

If specific gravity specifications are met,

reinstall cell caps.

CAUTION!

Only the use of genuine VW battery cell
caps ensures the different battery cover
systems are sealed correctly. Only use
genuine cell caps of the same
construction if lost or damaged. All cell
caps must be equipped with an O-ring
seal.

Battery, checking

13/2/2005