Remarks concerning totally discharged batteries

WARNING: This page does not describe the selected car, but rather 27 other vehicles, including the 2002 Volkswagen Cabrio, 2001 Volkswagen Cabrio, 2000 Volkswagen Cabrio, 1999 Volkswagen Jetta, and 1999 Volkswagen Golf. However, it is still accessible from the selected car via links, so may be relevant.

Batteries that have not been used for a long time (e.g. vehicles that have been stored) self-discharge.
A battery is totally discharged when the no load voltage has dropped below 11.6 V. Measuring no load voltage. Refer to NO LOAD VOLTAGE MEASUREMENT .
On totally discharged batteries the electrolyte (sulfuric acid/water mixture) is almost all water; the sulfuric acid part is heavily reduced.

Totally discharged batteries sulfate, causing the total plate surface of the battery to harden.
If a totally discharged battery is charged again shortly after totally discharging the sulfation dissipates.
If these batteries are not recharged the plates continue to harden and the ability to recharge is reduced. A reduction in the battery output is the result.

Totally discharged batteries must be charged with a small charging current as follows:

The charge current must be set at a maximum of 10 % of the battery capacity, therefore for a 60 Ah battery the charge current is a maximum 6A (ampere).
Charging battery. Refer to BATTERY CHARGING .
The charge period must be at least 24 hours.
Totally discharged batteries must never be charged quickly.

NOTE: After reconnecting battery:

Activate vehicle equipment such as radio, clock and power windows as per Repair Manual and/or Owner's Manual.
On vehicles equipped with OBD II, activate readiness code

Refer to appropriate ON BOARD DIAGNOSTIC (OBD) article