Checking relative density of electrolyte in all cells — AUDI

Warning:
When using sulphuric acid it is absolutely necessary that accident prevention procedures are observed. Suitable protective clothing must be worn.
When disposing of batteries it is absolutely necessary that disposal procedures for batteries and sulphuric acid are observed.
Ensure that following notes are observed otherwise correct check cannot be guaranteed.
In conjunction with "voltage under load" test, electrolyte density test gives a good indication of battery condition.

Special tools, testers and auxiliary items required

Commercially available hydrometer
Cleaning cloths

Notes:

A battery temperature of at least 10 oC is required when carrying out relative density tests.
The electrolyte density can be checked immediately after battery charging.

Remove all battery plugs (battery cell sealing plugs).

Immerse end of hydrometer in a cell and extract sufficient electrolyte so that float swims free in electrolyte. Repeat this test for all cells.
The greater the specific gravity (relative density) in kg/dm3 of the extracted electrolyte, the more the float rises. The relative density of electrolyte in kg/dm3 can be read off scale of hydrometer.

Differing relative density readings

Notes:

The difference between the relative density readings of individual cells must not be more than 0.04 kg/dm3.
The electrolyte density must be at least 1.24 kg/dm3.

Example of unacceptable deviations in relative density:

Differences in relative density (in kg/dm3) between cells
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

Relative density deviations in
example 1, cell 4 (1.10 kg/dm3), and
example 2, cell 4 (1.14 kg/dm3) and cell 5 (1.18 kg/dm3) are not acceptable. The batteries shown in examples are no longer usable and must be disposed of.

The following values must be attained:

Charge condition in normal climatic zones · Relative density (in kg/dm3)
discharged · 1.12
half charged · 1.20
well charged · 1.28

Charge level in tropical countries · Relative density (in kg/dm3)
discharged · 1.08
half charged · 1.16
well charged · 1.23

Warning:
It is essential that genuine and proper battery sealing plugs be used to ensure that differing battery cover systems are sealed correctly. Only use genuine sealing plugs of same construction if lost or damaged.
The plugs must be fitted with an O-ring seal.