How to rebuild a car battery? Car battery restoration

How to Fix a Car Battery

Car override: explained step by step

You want to reanimate a car? No problem: In our instructions, you’ll learn how to jump-start a car without damaging the onboard electronics.

When a car breaks down, the battery is most likely the cause. According to, around 40 percent of all breakdowns are due to problems with the power storage unit. Often, bridging is then the simplest solution.

For diesel vehicles, it is mandatory to use cables with a cross-section of at least 25 mm². Make sure the cables are flexible and the pole clamps are insulated except for the tips of the clamps.

Refer to the car owner’s manuals for possible special requirements for jumpering.

Jumpering a car battery: step-by-step instructions

1. before jumpering

If you have broken down on a busy road, secure the spot with a warning triangle and put on a high-visibility vest. This will help other road users to see the danger zone in good time.

Important: Make sure that the voltage of both the donor and the recipient vehicle is the same (twelve or 24 volts, newer cars increasingly have a 48-volt electrical system).

2. power up and shut down the engine

Make sure both cars are not drawing power before you start bypassing the battery. Check to make sure everything that needs power is turned off:

  • Lights
  • Music system
  • Air conditioning

3. identify plus and minus poles

Now identify the plus and minus poles on the batteries of both vehicles. This is important because if the wrong poles are connected, it can damage the electrical system. The result would be an expensive repair.

The respective symbols are usually molded directly into the plastic of the battery.

4. connect the cables

Then connect the jumper cables. First, connect the positive terminals of the two batteries to the red cable.

Then attach the black cable to the negative terminal of the donor car’s full battery. On the other hand, do not connect the other end of the cable to the negative terminal of the empty battery of the receiver car. Instead, select a so-called ground point. A metal point on the engine block is suitable for this.

Make sure that the clamps on the cable ends grip securely and that the cables do not touch the radiator fan or the V-belt. Otherwise, these components could be damaged when bridged.

Important: Never connect the black cable to the negative terminal of the empty battery! Otherwise sparks may be produced.

5. start the car

Then start the donor vehicle. Wait a few minutes and then start the receiver car. If it does not start, then wait a minute and try again.

But be careful: after three unsuccessful attempts at starting, there is a risk of damage to the battery. In such a case, get expert help.

Let both cars run for a few minutes.

6. switch on power consumers

Before you remove the jumper cables, you should take one more precaution: make sure that the broken-down car consumes a lot of electricity. For example, turn on the rear window heater or the fan.

This will prevent voltage spikes in the electrical system when you remove the cables.

7. removing the jumper cables

Now carefully disconnect the jumper cables, making sure to follow the sequence. First remove the black negative cable, then the red positive cable.

Then switch off the power consumers. 8.

8. what to do now?

Now drive the car for a longer distance – about 20 to 30 minutes. This will recharge the battery via the alternator. If error messages light up in the car display during this process, then call for professional help.

How long does a car battery last?

Battery failures are generally due to previous damage or the age of the component. After about four to five years, a battery has reached the end of its life. If the power storage unit is old or broken, then the only option is to replace it with a new battery.


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