Starting the engine from an auxiliary power source (Audi A4 B7)

Using an auxiliary power source will help start the engine in an emergency, but then you should find out and fix the cause of the battery discharge. The most common causes include:

• making repeated unsuccessful attempts to start the engine, or leaving the lights on for a long time with the engine not running;
• malfunction of the charging system (the alternator drive belt is loose or broken, the electrical wiring is damaged, or the alternator itself is faulty);
• malfunction of the battery itself (the electrolyte level has dropped or the battery's service life has expired).

When performing engine jump starting, some special precautions should be taken:

• you should not try to start the engine from a frozen battery - warm it up first;
• starting the engine from an auxiliary power source should only be done when the power unit and catalytic converter are cold;
• do not start the engine using a battery booster charger;
• before connecting the auxiliary battery, make sure the ignition is off;
• use only cables with sufficient cross-section and insulated terminals;
• make sure that all electricity consumers (lighting and heating devices, windshield wipers, etc.) were turned off;
• wear protective gloves and glasses;
• make sure that the auxiliary battery matches the battery installed in the faulty vehicle in terms of its output voltage;
• if a battery installed in another vehicle is used as an auxiliary power source, ensure that the vehicles do not touch each other;
• the donor car's engine must be running at idle speed;
• make sure the transmission is in neutral;
• remove the ventilation caps from the discharged battery and cover the holes with a rag.

Connect the end of one wire (usually red in color) to the positive terminal of the discharged battery. Connect the other end of this wire to the positive terminal of the auxiliary battery (see illustration 12). One end of the second wire (usually black in color) connect to the negative terminal of the auxiliary battery or to a ground point (for example, to the cylinder block) donor car.





Connect the other end of the black wire to a reliable ground point on the vehicle with the dead battery (not to the battery itself!). A special nut in the engine compartment should be used as a mass point.

Make sure that the connecting wires do not come into contact with moving components in the engine compartments of both vehicles (fan impeller, drive belts, etc.). Start the donor car's engine and run it at high speed for a few minutes. Follow the normal procedure for starting a car with a dead battery, then run it at high speed for a few minutes.

Disconnect the wires in the reverse order. Do not forget to install the removed ventilation caps on the battery.