A car battery can lose its ability to start the engine for a number of reasons: for example because it has discharged due to extremely cold weather, because it has reached the end of its life, or because the vehicle's lights are still on. all night long. In any case, regardless of the reason that caused the problem, you can start your broken down car by connecting the battery to that of a working vehicle using the appropriate cables. Make sure that both batteries have the same characteristics (voltage, amperage, etc.), then position the connecting cables correctly. At this point, the broken down battery should be receiving enough energy to start the car's engine.
Steps
Part 1 of 3: Locating and Preparing the Batteries
Step 1. Park the vehicles so that the two batteries are next to each other
Place the working vehicle next to the broken one. Normally a car battery is installed inside the engine compartment, so park the vehicle next to each other or facing each other. But be careful that the two vehicles do not touch each other.
Check the vehicle owner's manual if you are having difficulty locating the battery bay
The location of the battery and how to access it is clearly indicated in the manual.
Step 2. Apply the handbrake of both vehicles
The parking brake will ensure that none of the vehicles can move during the preparation and connection of the batteries. If your vehicle is equipped with an automatic transmission, move the lever to the "P" position. Alternatively, you can put the gear in neutral by moving the lever to the "N" position. If your vehicle has a manual transmission, put it in neutral, then activate the handbrake.
The handbrake is normally located near the gear lever and in modern vehicles it has been replaced by a simple button
Step 3. Turn off the vehicle and remove the keys from the ignition
Make sure the running vehicle is completely shut down before connecting. Check that the engine is not making any sound and that the radio does not turn on, to make sure the car is completely off and the power supply is cut off. Also remove the keys from the ignition of the broken vehicle, so that it cannot be accidentally started while you are connecting the cables.
In this case the engine of both vehicles is protected from a possible energy spike, thus reducing the risk of an electric shock
Step 4. Check the vehicle batteries to make sure they have the same voltage
The voltage supplied by the battery is clearly indicated on the label located on the upper side of the device (usually white or yellow). The label should have an entry similar to "12 V" in the case of a normal car (large vehicles such as SUVs or pick-ups may adopt batteries capable of delivering a higher voltage). The battery of the working vehicle must necessarily have the same characteristics as that of the broken down vehicle, because if it were more powerful it would send an excessive amount of current that could seriously damage the electrical system of the other car.
- Batteries that have a similar voltage are also similar in size. To avoid the risk of causing damage to vehicles, check the voltage printed directly on the label affixed to both batteries.
- If you are unsure whether the battery in the working car is compatible with the battery in the broken down vehicle, do not take unnecessary risks. Look for another vehicle or purchase a jump starter (this is a handy portable rechargeable battery).
Step 5. Locate the positive and negative poles of each vehicle's battery
The electric cable that is connected to the positive pole of the battery is normally red, while the one that connects to the negative pole is black. However, if you have any doubts, the battery should have the "+" and "-" symbols that denote the positive and negative poles respectively. The red cable must be connected to the positive pole "+" of the battery, while the black cable must be connected to the negative "-".
Before connecting the cables, check that there are no signs of corrosion on the battery poles. The residues left by corrosion are characterized by a white, green and blue powder. Clean the battery poles using a rag or a brush with iron bristles
Part 2 of 3: Connect the Cables
Step 1. Separate the two connection cables and their respective terminals by placing them gently on the ground at a certain distance
Lay both cables on the ground between the two vehicles. Leave enough space between the cable terminals so that they cannot accidentally touch each other. Failure to do so could result in a short circuit which could damage the electrical system of both vehicles.
Normally the connection cables are sold coupled, but with a different length, precisely to prevent the terminals from accidentally coming into contact with each other. Furthermore, the latter are externally coated with a protective insulating sheath. If the cables are paired and have the same length, carefully check for damage or signs of tampering
Step 2. Connect one of the two clamps of the red cable to the positive pole of the battery of the broken down vehicle
Leave the other end of the wire grounded as you connect. Before connecting the clamp to the battery, check again the "+" and "-" symbols on the battery to make sure you are using the correct pole. Press the grip of the clamp firmly to open it, then place it firmly around the battery pole and let go.
- On some vehicles the positive pole of the battery is protected by a red plastic cover; in this case you will need to remove it before you can connect. Normally this is done by simply turning it carefully counterclockwise with one hand.
- Connect the cable clamps one at a time. Carry out operations calmly and without haste to avoid making mistakes that could seriously damage both vehicles.
Step 3. Connect the other clamp of the red cable to the positive pole of the working vehicle's battery
Bring the cable closer to the second vehicle so that it can be plugged into the right position. Make sure the clamp is firmly anchored to the positive pole of the battery so it can't accidentally disconnect when you start the car's engine.
Remember that the red cable must connect the positive poles of both batteries, also marked by the red color and the "+" symbol
Step 4. Connect one end of the black cable to the negative post of the working vehicle's battery
Grasp the indicated cable clamp and bring it close to the charged battery. Firmly press the grip of the clamp and secure it firmly to the negative pole of the battery. Make sure that the cables connected to the working car do not touch each other and that the terminals are properly attached to the respective poles of the battery, then continue reading the next step.
If one of the terminals is not connected correctly, stop before starting the engine. Disconnect the cables and repeat the connection procedure by moving only one clamp at a time, preventing it from coming into contact with the others or with the other cable
Step 5. Connect the other clamp of the black cable to a bare (unpainted) metal part of the broken down vehicle
The free end of the black cable should not be connected to the negative pole of the broken-down car battery. In this case, find a metal spot, for example one of the bolts on the engine block, and connect the clamp to it. Alternatively, you can opt to use an unpainted part of the car frame that is accessible from the engine compartment.
- Avoid connecting the clamp directly to the negative pole of the dead battery unless you have no other choice. In this case the risk of a spark being generated when the car is started is very high, so the hydrogen fumes that are released from the battery could ignite.
- Don't go too deep inside the engine compartment to find a metal spot to connect the black cable clamp to. In the lower part of the car passes the pipe that carries the fuel from the tank to the engine which should remain at a safe distance from the clamp of the connection cable.
- Make sure that the connecting cables cannot come into contact with the moving parts of the engine once it is started.
Part 3 of 3: Starting the Vehicles
Step 1. Start the engine of the running car and let it idle for a few minutes
To start the vehicle normally use the ignition key. The electrical system of the broken car will resume working as soon as the energy begins to flow to the battery, so elements such as the lights or the radio will be functional again. Wait at least 30 seconds before trying to start the second car so that the battery has time to recharge.
- Depending on the condition and age of the broken car's battery, you may have to wait longer to allow it to accumulate enough charge to start the engine.
- If you need to make more current flow to the battery to be recharged, press the accelerator pedal of the vehicle in motion, to get the engine rpm to 3000 RPM.
Step 2. Start the engine of the broken down car
Turn the ignition key to start the vehicle's engine. At this point the electrical system should activate immediately. If the warning lights in the instrument cluster, passenger compartment lights, radio and other electronic devices in the car do not come on, it means that the battery may need more time to accumulate a minimum amount of energy sufficient to power the electrical system of the car. vehicle. Turn the ignition key to the "Off" or "0" position, make sure the cables are properly connected to both batteries, then increase the engine RPM of the running vehicle to increase the current flow to the battery under charge.
- If the broken down vehicle does not start after a few attempts, it is very likely that the problem is not the flat battery. The cause could be a blown fuse that needs to be changed.
- If the instrument warning lights and car lights come on, but the engine does not start, the battery is not the cause of the problem. When you try to start the engine you should hear the starter turning. Conversely, if you hear no noise or just a simple "click", the cause of the problem may be a malfunctioning or replacement starter motor.
Step 3. Disconnect the cables from the battery in the reverse order, starting with the black cable
Remove each cable clamp in the exact reverse order you used to make the connection. Start by unplugging the black ground wire clamp, the one you connected to a metal part of the broken down vehicle. At this point, remove the clamp of the black cable and that of the red cable connected to the battery of the working vehicle. Conclude the procedure by disconnecting the clamp of the red cable from the broken down battery which is now working perfectly.
- Leave the car running for several minutes so that the battery can fully charge because otherwise it will not have accumulated enough charge to start the engine and you will have to repeat the whole procedure from the beginning.
- Be very careful when disconnecting the cables from the battery so that the clamps do not touch each other until you have removed them from both vehicles.
Advice
- Some vehicles are equipped with a plastic cover to hide (and isolate) the battery from view. In this case you will need to remove the protective cover first in order to connect the cables. Normally it is press-fit, but in some cases it is fixed by some screws that you will have to remove by hand or with a screwdriver.
- After starting the car with the cables, keep it running for at least 15 minutes so that the battery can fully recharge.
- In some vehicles, the battery is not located inside the engine compartment but is located under the rear seat of the passenger compartment or even in the trunk. In these cases there should be a connection point inside the engine compartment that allows access to the positive pole of the battery. It is usually characterized by a red cover and a "+" symbol. After removing the protective panel, connect the red cable to the point indicated.
- Short connecting cables allow you to do a better job, as the electric current will have to travel a shorter distance. On the contrary, using very long cables causes a loss of energy and an increase in charging times.
- Get a portable battery to start a broken down car so you don't need to use a second vehicle. Make sure to fully charge it using the USB port or its power supply, connect it to the jump leads included in the package at the time of purchase and connect it to the car battery to start, as you normally would if you had a second vehicle available.
Warnings
- Avoid powering a frozen battery with cables, as it may explode. If you have the opportunity to inspect the inside of the battery, make sure that the liquid in it has not frozen. However, if the sides of the battery are deformed and appear rounded outwards, it is very likely that the liquid inside has completely frozen.
- Car batteries release a highly flammable hydrogen-based gas, so try not to smoke in their vicinity. Also make sure not to connect the black ground wire to the negative pole of the broken battery.
