Charge battery

Special tools, testers and auxiliary items required

Fig 1: Battery Charging Unit VAS 5095 A

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Fig 2: Battery Charging Unit VAS 5900

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Fig 3: Battery Charging Unit VAS 5903

Courtesy of VOLKSWAGEN UNITED STATES, INC.

CAUTION: Valve-regulated lead-acid batteries and AGM batteries must be protected from overvoltage.

NOTE:

Battery chargers VAS 5095A, VAS 5900 and VAS 5903 charge without current and voltage peaks. Batteries can therefore also be charged when installed. When doing this, heed the safety instructions. The devices provide an assistance mode in which they provide supply for the circuits.
When working on the electrical equipment with components temporarily switched on, and for "Guided Fault Finding", the battery must be charged with a battery charger with assistance mode to prevent damage to the battery.

CAUTION:

It is recommended that the battery is charged when installed and connected. Only in this way it is guaranteed that the charge current is included in the capacity of the Energy Management Control Module J644.
Battery plugs must always be threaded in so they seal properly for charging, voltage measurement and load measurement.
Battery must not be quick-charged.

CAUTION:

Provide sufficient ventilation.
There should be no open lights or smoking in rooms where batteries are being charged. The reason for this is that gas builds up during the battery charging process, which can easily ignite.
Heed the safety regulations of the battery and battery charger manufacturers.

Work procedure

Sedan:

Fig 4: Identifying Luggage Compartment Cargo Floor And Spare Wheel Cover

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Avant:

Remove luggage compartment storage area floor - 1 - and cover for spare wheel - 2 -.

Fig 5: Identifying Cover, Ground Pin, Battery Charger Pliers, And Ground Wire Pliers

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Vehicles with ground (GND) pin in luggage compartment:

Remove cover - 2 - above battery positive terminal.
Clamp battery charger pliers - 1 - of positive wire to batterys B+ terminal.
Clamp ground (GND) wire pliers - 3 - of battery charger to ground pin - arrow - of Energy Management Control Module J644.

Vehicles with ground (GND) pin in engine compartment:

Open cover - arrow - above battery positive terminal.
Clamp positive wire clamp of battery charger to B+ terminal tap, and clamp ground (GND) wire pliers of battery charger to negative terminal tap.

All:

Adjust charge current at battery charger according to battery capacity. It should amount to approx. 10 % of the battery capacity. For a 60 Ah-battery, approx. 6 A.
Switch on battery charger.
Keep lid open while charging.
Perform battery test after charging process → Charge battery ..

Severely discharged batteries

Batteries which have not been used in driving operation for a long time, for example in stored vehicles, discharge themselves.
A battery is severely discharged, when the resting voltage has dropped below 11.6 volts. With voltage between 12.2 and 11.6 V, the battery is pre-damaged. Measuring open-circuit voltage → No load voltage, checking .
In severely discharged batteries the electrolyte (a mixture of sulfuric acid and water) consists almost entirely of water, since the proportion of sulfuric acid is strongly reduced. At minus temperatures, the battery can freeze and the casing can crack.
Severely discharged batteries can sulfatize, i.e. the complete plate-surfaces of the batteries can harden. The battery acid is not clear, it has a slightly white color.

If severely discharged batteries are recharged again shortly after having been severely discharged, the sulfation forms again.
If these batteries are not recharged, the plates continue to harden and the charge-retention ability becomes limited. The consequence is reduced battery performance.

Procedure for charging severely discharged batteries, which are sulfatized

Severely discharged batteries which are sulfatized must be charged with a small charge-current as follows:

Adjust charging current to approx. 5 % of the battery capacity, i.e. for a 60 Ah battery, the charging current is then to approx. 3 Ampere.
Charge battery → Charge battery . The charge voltage (U max) may only amount to a max. of 14.4 V (volt).

NOTE: