Caution: If the wiring connections are not strictly followed, there is a risk of burns from battery electrolyte discharge. In addition, injuries or damage may occur due to battery explosion. In addition, the vehicle's electrical system may be damaged.
The cross-section of the jumper cable for petrol engines with a displacement of up to approximately 2.5 litres must be at least 16 mm² (diameter approximately 5 mm). For diesel engines and petrol engines with a displacement of over approximately 2.5 litres, the cross-section of the cable must be at least 25 mm². The displacements are specified for a vehicle engine with a discharged battery. The cross-section of the cable is usually indicated on its packaging. When purchasing a new cable, it is recommended to purchase an auxiliary jumper cable with insulated clamps and a cross-section of 25 mm², as it is also suitable for engines with a smaller displacement.
Both batteries must be rated for 12V.
A discharged battery can freeze at temperatures as low as -10°C. Before connecting the auxiliary jump lead, the frozen battery must be thawed.
The discharged battery must be properly connected to the vehicle's electrical system.
Check the electrolyte level in the discharged battery and top up with distilled water if necessary.
The cars should be placed at a distance that excludes contact with their metal parts. Otherwise, current may flow when the positive pole is connected.
Put both cars on the handbrake. Set the gear selector to neutral, if there is an automatic transmission, set the mode selector lever to position P.
Turn off all power consumers.
During the starting process, the engine of the vehicle supplying the current must be idling. This helps to avoid possible damage to the generator due to voltage peaks during the starting process.
During the starting process, avoid open flames or burning cigarettes near the battery, as flammable gases may be released from it.
Make sure that the jumper cable is not damaged by rotating parts such as the radiator fan.
Connect auxiliary wires in the following sequence:
- 1. Connect the red wire (+) to the positive pole of the discharged battery "A".
- 2. Connect the other end of the red wire (+) to the positive pole of the battery "B" that supplies current.
- 3. Connect the black wire (-) to the negative pole "3" of the battery that supplies current.
- 4. Connect the other end of the black wire (-) to the body of the vehicle receiving the current using the "X" clamp. A metal part firmly screwed to the engine is best suited for this. Under unfavorable circumstances, when connecting the wire to the negative pole of a discharged battery, it may explode due to sparking and the formation of detonating gas in it.
Check the tightness of the jumper cable connections again.
Caution: The terminals of the connected jumper cable must not come into contact with each other, nor must the positive terminals come into contact with any part of the chassis (body or frame).
Start the engine of the vehicle receiving the current (with a discharged battery) and let it idle. When starting, do not keep the starter continuously running for more than 10 seconds, since the clamps and wires heat up due to the high starting current. The pause between two consecutive starting attempts should be at least 1/2 minute.
Do not lean over batteries - risk of electrolyte burns!
After starting, disconnect the wires in the reverse order: first disconnect the black wire (-) from the car receiving the current, and then from the car giving the current. First disconnect the red wire from the car giving the current, and then from the receiving one.