1. Making repeated unsuccessful attempts to start the engine, or leaving the lights on for a long time with the engine not running;
2. Malfunction of the charging system (the alternator drive belt is loose or broken, the electrical wiring is damaged, or the alternator itself is faulty);
3. 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:
- Do not attempt 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 use a battery booster charger to jump start the vehicle;
- 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 also turned off;
- Wear protective gloves and glasses;
- Make sure that the auxiliary battery output voltage matches the set 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 (manual transmission) or in position "P" (automatic transmission);
- Remove the ventilation caps from the discharged battery and cover the holes with a rag.
1. Connect the end of one wire (usually red in color) to the positive terminal of the dead battery or to the positive terminal in the engine compartment. Connect the other end of this wire to the positive terminal of the auxiliary battery.
2. One end of the second wire (usually black in color) connect to the negative terminal of the auxiliary battery or to a ground point (upper front strut mount or cylinder block). Connect the other end of the black wire to a reliable ground point on the block of the engine being started (bolt or bracket), as far away from the battery as possible.
3. 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.).
4. While maintaining the donor vehicle's crankshaft speed at 2000 rpm, perform the standard procedure for starting the engine of a vehicle with a discharged battery, then let it run for several minutes at high speed.
5. To prevent voltage surges when disconnecting the wiring, turn on the rear window defroster and heater fan, then disconnect the wires in the reverse order of their connection. Do not forget to install the removed vent caps on the battery.
(The original text can be read on the website «bmwman.ru»)