The battery is self-discharging (VW Transporter T3)

If you suspect that there is a leakage current, you need to check the on-board electrical system.

Use a charged battery to check.

Set the ammeter with a measurement range of 0-200 A to the upper scale. Disconnect the ground from the battery. Connect the ammeter between the negative pole of the battery and the ground. Connect the "+" clamp of the ammeter to the ground, and the ammeter clamp to the minus pole of the battery.

Turn off all current consumers, remove the terminals from the clock, close the doors.

Switch the ammeter to ever smaller measurement ranges until it becomes possible to read its readings (1-3 mA is acceptable).

Disconnect various electrical circuits by pulling out one fuse after another. If the ammeter readings drop to zero when disconnecting any k target, the fault should be sought in that circuit. The sources of the fault may be: rusty or dirty contacts, worn conductors, internal short circuits in 8 different units.

If the fault is not found in the circuits provided with fuses, it is necessary to disconnect the conductors from the remaining devices. Such devices are: generator, starter, ignition system, control panel devices, connect the battery to ground.