Minimum voltage car battery

The only source of current at the start of the car is the battery. With its help, the engine is started, which in turn starts the generator. From this point on, the battery ceases to be a source of current and becomes its consumer. During operation of the motor, the voltage of a charged car battery rises and returns to normal.

However, during frequent short trips the battery does not have time to charge, there is a constant and regular decrease in charge. In this case, you need to restore the current level using external devices. Consider how it is done to what level, and how much time is spent on such a process.


  • 1 low battery
  • 2 Normal parameters for battery
  • 3 Proper battery charging
  • 4 Safety Rules

Low battery

Most of the situations in which the car battery is discharged, happen through the fault of drivers. Less often, the reason lies in the design features or factory marriage. A battery often reduces its charge if there is an insufficient level of tension on the generator belt. Due to this, belt slippage and insufficiently effective operation of the generator occurs.

What could be the charge voltage of a car battery

The same problem occurs when the door is not tightly closed or the trunk is not fully closed until the end. The blame in this case will serve working light bulbs. For several hours they can significantly reduce the level of charge.

Normal parameters for battery

Существует ряд параметров, которым должен соответствовать нормально работающий аккумулятор. Рассмотрим, up to what voltage can the car battery be discharged, но при этом надо знать, что слишком сильный уровень разряда способствует скорому ухудшению характеристик АКБ.

A battery is considered to be operable with the following indicators:

  • with open circuit - 12.6-12.8 V;
  • when the engine is running, the “high beam” is on and the engine speed is about 1500 rpm 13.8-14.2 V;
  • on serviced batteries electrolyte density at +20C will be 1.28 g / ml.

What should be the voltage of a charged car battery

There are also indicators for which you need to raise the voltage in the battery:

  • with the terminals open, the charge voltage of the car battery is less 12.6 V;
  • the electrolyte density in the battery being serviced is significantly lower 1.26 g / ml;
  • the difference in density between banks is battery over 0.2 g / ml.
See also: How to make a stroboscope for cars with their own hands

The level of electrolyte density is measured under normal conditions, which are characterized by an atmospheric pressure of 760 mm RS and +20C. At negative temperatures, it is desirable to increase the density of this liquid. Normal parameter for -20C is considered to be a density of 1.4 g / ml, since 1.2 g / ml begins to freeze under such conditions.

Proper battery charging

If measured with a voltmeter or multimeter shows the minimum voltage of the car battery, then charge. For this operation, you need to configure the charging device to produce a current in the range from 0.05 to 0.1 numerical value of the capacitance. Accordingly, for the 55 Ah battery, an amperage of 2.75-5.5 A is used. The most gentle mode will be with smaller values.

up to what voltage can the car battery be discharged

The output voltage for this operation should be 14.4-14.6 V. It is desirable that the device be able to set a static value. When a 55 Ah battery is completely discharged, it is necessary to withstand 10 hours with a current of 5.5 A.

A sign of the end of this procedure can be the unchanged voltage at the terminals within 1-2 hours after the establishment of the specified parameters.

Light signs of boiling with slight flatulence are also possible. On automated chargers, shutdown occurs automatically. The current and voltage supply is regulated in the same way.

Safety regulations

You need to know that acid is the basis for the electrolyte, so you must be extremely careful when handling the battery. It is necessary to avoid getting liquid on the hands, while protecting the skin with rubber gloves.

what is the minimum voltage of the car battery

During boiling inside the battery poisonous gases are emitted. They can not be inhaled, so the charging process should be organized in a room with good ventilation, preferably forced. It is also possible the release of explosive hydrogen, therefore it is necessary to exclude the use of open fire and sparking. You should not leave homemade chargers unattended for a long time.