Battery, Charging

Battery, Charging

Special Tools and Equipment
- Battery charger

The battery should be charged using a VAG battery charger, for example VAG1471, VAG1648 or VAS1974.


WARNING!
Battery plugs must always be threaded in so they seal properly for charging, voltage measurement and load measurement.

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.


NOTE:
- The battery must have a temperature of at least 10 °C.
- Batteries should only be quick-charged in exceptional cases (e.g. start help); quick-charging damages them.
- If severely discharged batteries are quick-charged, they do not take up any charge current, or indicate a "full" reading too early, due to "surface charging". They appear to be in good condition.


Procedure
- Switch off battery charger.


NOTE:
- Obtain radio code before disconnecting battery.
- Be sure to activate vehicle features (radio, clock, electric window regulator, engine) when the battery is re-connected.







- Remove cover above the battery (arrows).


NOTE: For vehicles without separate battery cover: Remove plenum cover.







- Disconnect Ground (GND) strap -1- at battery Ground (GND) terminal by loosening hex nut (size = 10 mm).
- Loosen B+ wire -2- at battery B+ terminal by loosening hex nut (size = 10 mm).







- Connect battery charger B+ wire to battery B+ terminal.
- Connect battery charger Ground (GND) wire to battery Ground (GND) terminal.
- 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.

Further information on 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. Measuring resting voltage. Open Circuit Voltage, Measuring

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 charge-current to approx. 5 % of the battery capacity, i.e. for a 60 Ah-battery the charge-current then amounts to approx. 3 A (ampere).

Performing battery charge.
The charge voltage (Umax) may only amount to a max. of 14.4 V (volt).

Severely discharged batteries should never be charged quickly.