Why the car battery does not charge well from the generator

The only source of current during the start of the ignition of the car is the battery. With its help, it is possible to start the engine. After this, the load falls on the generator, and the battery switches to the mode of power consumption.

Однако, так случается с полностью работоспособной системой электропитания в транспортном средстве. Когда возникают неполадки, то приходится искать причины, выясняя, Why is the battery not charging?, и как восстановить работоспособность.


  • 1 When the battery does not charge
  • 2 Simple causes and methods of "treatment"
    • 2.1 The internal state of the battery
    • 2.2 Terminals
    • 2.3 Generator belt
  • 3 Control of the remaining elements of the charging system
  • 4 Generator check
  • 5 Conclusion

When the battery does not charge

The absence of a charging process may be indicated by the indicator light on the dashboard. Often it is depicted in battery icons, and with satisfactory work, electrics with a running motor do not glow. It will be possible to examine it on the dashboard after turning the key in the ignition lock to the first position. If the icon continues to glow, it means that the battery is not charging from the generator.

Why is the battery not charging? в автомобиле

The reasons may be different for each car. In some cases, the culprit is the battery itself, and besides its replacement, the problem cannot be solved anymore. It happens, the situation arose because of the generator node. Other causes are less common.

Simple causes and methods of "treatment"

If there is such an opportunity, then you can go the easiest way and put a neighbor in place of your battery, moreover, the second one will be guaranteed to work. When the charging process goes, the experiment can be considered successful, and you will need to replace your own battery.

The internal state of the battery

Usually the reason that a battery does not charge well is due to sulphation, when the surface of the plates is partially or completely coated with salts that impede the process. With a low degree of coverage, you can restore everything partially or completely, and with irreversible processes of destruction of the plates, you will only need to replace the entire battery.

Recovery from sulfation may take more than one day., and the result is not always guaranteed. This means that a new battery will definitely be needed soon. Resuscitation is usually started in the event that there are no signs of bloating, visible cracks or any suspicious chips.

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Why is the battery badly charged?

But the outermost state is no guarantee that the result will be successful. Inside the cans, chipping off pieces of plates occur, which lead to a short circuit. Such a battery will only be disposed of.


In some situations, the indicator may light up while driving. Inexperienced drivers can panic, figuring out what to do if the battery is not charging. It is enough to drive off the road and open the hood. Most likely, a loose contact with a terminal has flown on an uneven road. It is enough to bring it back and tighten it with a screwdriver.

Terminal troubles also appear when their surfaces are oxidized at the junction with the contact. You will need fine sandpaper or a small round file to clean the contact from oxides.

for whatever reason the battery is not charging from the generator

You need to know that when working with a file you should be careful, as the soft lead part of the contact is easily cut off.

If you cut with a file more than you need, then the contact will be bad to hold and constantly fall down on the bumps.

Generator belt

Finding out why the car battery is not charging from the generator, it is worth checking the condition of the belt drive. Weak tension leads to belt slippage on the pulleys, and the generator at this time does not produce electricity into the system. There is a switch to the battery, which passes from the consumer to the voltage source, gradually discharging.

You can check the belt tension with the engine off. At the same time, if necessary, it can be tightened. However, the wear of the belt profile also leads to slippage. This is not restored, and is solved only by buying a new belt.

Wet or wet pulley does not transmit rotation. The belt slides over the surface without effort. It is enough to dry it and get rid of the source of moisture.

Why is the battery not charging?

Slipping is harder to notice, but a broken belt can happen. In this case, it is enough to replace it. The detail is popular, and on popular car models it can be found in almost any auto shop.

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The generator oxidizes the wires at the junctions. A noticeable white coating is easily cleaned with sandpaper. It is necessary to check the wires visually for breaks or burnt contacts. Often the blown wire can be heard from the characteristic smell of burnt insulation.

Control of the remaining elements of the charging system

If the visual control did not give any results, then you need to use a multi-meter and measure the battery voltage in several states. A check at the terminals with the motor turned off and the contacts open should give a result in the range 12.5-12.7 V. This is a state of a normally charged battery.

why the battery is not charging from the generator

After that, control is carried out on the engine. Normal data must be in the interval 13.5-14 V. At lower rates, we raise the momentum and identify the dynamics of voltage changes. Reducing the value indicates problems with the diodes in the regulator relay or the brushes. The latter should be checked for erasing or breaking the chain.

The identified inoperability of the regulator relay can be eliminated by replacing it completely or by self-soldering the diodes in the bridge. Such work requires a powerful soldering iron and high-temperature solder. It is necessary to select the most close to the technical parameters of the diodes so that they do not overheat during operation, as in this case the current will go above the nominal.

Generator check

Lack of battery charging may occur due to internal state in the generator. In cars with high mileage happens the development of the rotor, the wear of rotating surfaces. Due to this, skewing and absence of rotation occur. The jammed generator must be replaced completely.

what to do if the battery is not charging

There are breaks in the circuit exciting the generator. It is unlikely that this problem can be solved on its own, and therefore it is also solved by visiting a car shop and buying a generator.


Many problems with weak charging the battery or its complete absence can be solved independently without the help of auto service specialists. It should be attentive to the light indicator, indicating a weak charge, in time to rectify the situation.