Electrolyte specific gravity, measuring - batteries with sealing plugs

Special tools, testers and auxiliary items required

Fig 1: Refractometer T10007

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Fig 2: Identifying Commercially Available Hydrometer

Courtesy of VOLKSWAGEN UNITED STATES, INC.

CAUTION:

Observe accident prevention directions when handling battery acid Electrolyte: .
Appropriate safety clothing is required Eye protection and protective clothing: .
Maintenance-free batteries must not be opened for checking the acid density, otherwise warranty expires.
When disposing of batteries, disposal regulations for batteries and for sulfuric acid must always be observed.

NOTE:

The electrolyte density test, in combination with the battery load test, provides information about the condition of the battery.
The temperature of the battery acid must be at least 10 ° C.
The electrolyte density can be checked directly after the battery is charged.

Fig 3: Hydrometer Specific Gravity Reading

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Work procedure

Remove all sealing plugs of battery cells.
Dip hydrometer into battery cell and siphon off enough electrolyte until float floats freely in electrolyte.

The larger the specified weight of the siphoned battery acid, the higher the float will float.
The acid density of the electrolyte can be read off in kg/dm ³ on the hydrometer scale (specified density of the battery acid).

Read off measured value at hydrometer and compare to indicated values in the table:

Charge condition in normal climates	Electrolyte density in kg/dm ³
Discharged	1.12
Half-charged	1.20
Good charge	1.28

Charge condition in tropical climates	Electrolyte density in kg/dm ³
Discharged	1.08
Half-charged	1.16
Good charge	1.23

Specified acid density must be at least 1.24 kg/dm ³ in moderate climate zones. If the acid density in all battery cells is too low:

Example 1

Battery cell	1	2	3	4	5	6
Electrolyte density per cell in kg/dm ³	1.24	1.25	1.25	1.10 ¹⁾	1.24	1.25
¹⁾ Acid density in cell 4 is too low (deviation greater than 0.03 kg/dm ³ ).

Example 2

Battery cell	1	2	3	4	5	6
Electrolyte density per cell in kg/dm ³	1.26	1.26	1.25	1.14 ¹⁾	1.18 ¹⁾	1.24
¹⁾ Acid density in cells 4 and 5 too low (deviation greater than 0.03 kg/dm ³ ).

If specified values are not obtained:

NOTE:

The measured values for the acid density for individual battery cells may not deviate more than 0.03 kg/dm ³ from each other, otherwise replace battery.

If specified values are obtained:

CAUTION:

To ensure proper sealing of the different battery cover systems, the original battery plugs must be threaded into the battery openings. In case of loss or damage, only original sealing plugs of the same type may be used.
The plugs must be equipped with an O-ring seal.