You’ve probably noticed that I’ve been writing a lot about car batteries lately, I just opened a new section on the site and I want to cover all the “hot questions” - read a lot of useful stuff. Another very pressing topic is battery overcharging. Today I will try to tell you what the reasons may be, as well as the consequences of this phenomenon, why overcharging a battery is just as bad as undercharging it. Read on...

I have already pointed out more than once that the battery contains a small amount of electrolyte; for each model it depends on the power differently. It is this electrolyte that contributes to the accumulation of energy, without it there would be no effect of the battery (rechargeable battery). But this liquid is very capricious; it needs to create necessary conditions- so that it does not freeze, and also so that it does not boil over. If so, then “boiling” of the battery may be caused by overcharging, and this is already serious. Something needs to be done.

What is recharge?

If you explain it in words, this is a fairly simple process - the battery is already charged, the generator continues to charge and charge. The electrolyte contains a proportion of water, which is quite large, about 65% (the rest of the composition is sulfuric acid 35%), under normal circumstances the battery gains a charge (raises the density to the desired level) and turns off, so its voltage is 12.7 Volts , this is the average 100% voltage across many batteries.

If you continue to charge the battery, the water inside the electrolyte will begin to disintegrate into its constituent gases, and these are hydrogen and oxygen - the electrolyte will boil or boil, and accordingly the water level will drop (evaporate) - the more current you apply, the more intense it will be - This is classic battery recharging.

Accompanied by intense boiling and a decrease in the electrolyte level. In fact, this phenomenon is much more dangerous than, say, “undercharging.”

If the battery is not fully charged, you simply will not start your car, but if you overcharge, the battery may simply explode.

Reasons for this phenomenon

Guys, I’ll say a few words about “special” recharging from a charger - many people do this on purpose! REMEMBER! Thus - to the required level - in our band it is approximately 1.27 g/cm 3, if the density is lower (already with a charged battery), then the battery may freeze at sub-zero values. We need to raise it! How to do this? It’s very simple - you need to evaporate a small amount of water from the electrolyte, thus the acid concentration will increase and the density will increase.

Therefore, many car enthusiasts “boil” the battery at a low current, from the charger, but only up to a certain density value. After this, charging is turned off. Otherwise, you will simply ruin the battery. It is especially important to prevent the plates from being exposed.

Now “non-special” overcharging, as they say under the hood of the car, its main reasons:

• The generator charge regulator relay has failed . This relay “sees” charging, and when it reaches 12.7 Volts, it turns off the power supply from the generator. If this relay fails, then the generator will constantly charge the battery, and its currents are considerable, it will boil very quickly! This is the most common reason. Fortunately, this relay costs a penny. A short video, let's watch.

• The generator itself has failed , this also happens. For example, we changed the relay, but nothing helps, it’s constantly charging! The generator needs to be repaired or replaced; here the repair is more complicated and more expensive.

• ON some vehicles, for example on trucks, also on some UAZ, costs a voltmeter , it shows the voltage from the generator to the battery, that is, how it charges it. Usually it should not exceed 14 Volts, but often the readings are 15 - 17 Volts, which is a lot. I had such a case in practice - they replaced both the relay and the generator, everything is new, but the voltmeter shows 17 Volts, we were already confused about what to do! It turns out that the sensor itself had failed, they changed the display and everything was fine, the voltage leveled out at 14 Volts. So the moral is this - sometimes the sensor itself fails - there is no overcharging, it just shows “false” readings.

These are the most common reasons why the charge goes beyond the norm, in fact, there is nothing else to break, unless you have some kind of Lexus in which there are just a lot of sensors, there may be something else, although it seems to me that it’s unlikely - whether.

Fortunately, in new cars, two indicators on the panel will light up, this and also the battery icon.

Many will say - so what, it’s reloading, and screw it, what will happen? But don’t tell me guys, we’re reading about the consequences.

Consequences of overcharging

So, for those who believe that all this is not serious and you can ride with it, I’ll dedicate it to you, I’ll break it down point by point:

• Overcharging causes the electrolyte to boil, it splashes onto the surface of the battery, and then flows onto many parts under the hood, for example: - terminals, pipes, body metal, radiator, wires, etc. Since there is acid present here (even if not concentrated), it can still corrode everything that I have listed for you, even if not immediately, but it will do it.

• Terminal oxidation. Since acid gets on the terminals, they will oxidize very quickly and a green coating will appear.

• The electrolyte level drops, the lead plates are exposed, but the charge continues! Thus, they will heat up, which has a negative effect on them - if you do not dehydrate them for a long time, they will “crumble”, the banks may short out, or the battery will die altogether. Just throw away the battery.
• Since the electrolyte evaporates, and these are essentially explosive gases (oxygen and hydrogen), the battery itself can explode, and it won’t seem like much. All engine compartment will be in acid.

The car battery voltage is a leading indicator on the basis of which a competent driver should draw conclusions about the condition of the battery, whether it needs charging or replacement. It is known that there is a direct relationship between voltage and charge level car battery. First, we will consider the question of what voltage indicators can be used to draw a conclusion about the performance of the battery, why the battery loses U and what the voltage standard means. After this, we will try to determine the battery charge by voltage: a table on the basis of which certain conclusions about the state of the battery are drawn will be attached at the end of the article.

The battery loses voltage: what is the reason?

If a charged power source quickly discharges, there may be several reasons for this “behavior” of the battery. The battery charge level can quickly drop due to a natural reason: the battery has simply exhausted its resource in the usual way and needs to be replaced.

The generator, which charges the battery while driving, may also fail, helping it maintain the required level of operating condition. If the battery is not yet old and the alternator is in order, the car probably has serious problems with current in the form of constant leakage.

In addition, the car’s on-board network may be faulty - for example, the radio or some other device takes too much current, and the battery simply cannot cope with this load.

In order to eliminate the voltage drop, sometimes it is enough to correct the problem by technical inspection, identifying the cause, eliminating it and re-measuring the voltage at the battery terminals after several hours of operation. It is important to evaluate indicators such as level, as well as measure voltage under and without load.

What does normal battery voltage mean?

For normal battery operation, its voltage should fluctuate between 12.6-12.7 volts, no less. This norm should be learned by novice drivers, like a multiplication table - in order not to miss the critical level of battery charge drop and not to find yourself in a position where the car suddenly “stops”.

You should also know that, depending on the characteristics of the battery and vehicle, as well as other related conditions, the norm may vary - up to 13 volts and slightly higher. This is exactly what some battery manufacturers say, and this factor also needs to be taken into account. How many volts should ideally be is a relative figure. But you should always focus on readings from 12.6 to 13.3 volts - depending on the type and country of origin of the battery.

If the voltage in the battery drops below 12 volts, it is at least half discharged, and when it drops below 11.6 volts, the battery urgently needs charging.

So, the norm of the voltage indicator for the most part car batteries- from 12.6 to 12.7 volts, and if a non-standard battery model is used, the U norm may be slightly higher: 13 volts, but a maximum of 13.3. Some novice motorists ask what the ideal U-value should be. Of course, there are no ideal numbers, since the current level in the car’s network, weather conditions, and energy consumption can change. separate elements on-board network car.

In order not to miss the moment when the battery charge begins to drop to a critical level, there is a so-called battery charge table. If you measured U at the terminals of your battery, you can determine the battery charge by voltage: the table will help you navigate this. It shows a directly proportional dependence of U on the charge level of the battery as a percentage.

The table also shows the density of the electrolyte and the temperature at which it can freeze in the cold season - also depending on the charge level and U in the battery.

Battery charge level table

Electrolyte density, g/cm³	Voltage without load	Voltage under load 100 amperes	Battery charge level, %	Electrolyte freezing point, °C
1,11	11,7	8,4	0	-7
1,12	11,76	8,54	6	-8
1,13	11,82	8,68	12,56	-9
1,14	11,88	8,84	19	-11
1,15	11,94	9	25	-13
1,16	12	9,14	31	-14
1,17	12,06	9,3	37,5	-16
1,18	12,12	9,46	44	-18
1,19	12,18	9,6	50	-24
1,2	12,24	9,74	56	-27
1,21	12,3	9,9	62,5	-32
1,22	12,36	10,06	69	-37
1,23	12,42	10,2	75	-42
1,24	12,48	10,34	81	-46
1,25	12,54	10,5	87,5	-50
1,26	12,6	10,66	94	-55
1,27	12,66	10,8	100	-60

A discharged battery does not always require purchasing a new one; often it is enough to charge the old one; the procedure is inevitable with frequent cold starts and short trips. The most affordable chargers have manual control, the owner must know what voltage to charge the car battery.

Requires direct current, voltage up to 16.5 Volts. Charging occurs in one of two modes: at constant current or constant voltage.

Charging the Bosch battery

The charger sets the current strength to 10% of rated capacity. For example, a 12 Volt battery with a capacity of 55Ah requires a current of 5.5A, for a 60Ah battery - 6A. In this case, the current strength must be regularly monitored and adjusted, as it tends to go astray.

If the current is maintained at 10% at the end of the charging process, strong gas evolution occurs. Therefore, when reaching 14.4 Volts, the current strength is reduced by 2 times. U maintenance-free batteries it is halved again when the voltage shows 15 volts.

Find out the charging time of your battery

A 12 Volt car battery is charged when its voltage and current do not change for 2 hours. For full operation, it is enough to save the parameters for 1 hour. This usually occurs at 16.3(±0.1) Volts.

Voltage-saving charging

A 12 Volt battery will be charged in a day:

For a heavily discharged battery, the current at the beginning of charging can reach high values, which can lead to battery failure, so the indicator is limited to 20A.

As charging progresses, the current decreases and eventually approaches zero. This method does not require constant monitoring by the owner. You can control the process a day after the start by measuring the voltage at the terminals. If it is 14.4(±0.1) Volts, charging is complete. Maintenance free batteries It usually takes more than a day to achieve this indicator. On devices equipped with an indication, a signal will light up indicating completion.

Charging calcium batteries

Old dry-charged batteries are charged with a 10% current; a voltage of up to 16 Volts is permissible for them. New 12 Volt Ca/Ca batteries quickly fail due to such high voltage.

The maximum permissible value for them is 14.4 Volts at a current of 10% of the capacity. Such charging requires more time, but does not shorten the life of the battery.

Charging 6 Volt batteries

6 Volt batteries are often used in:

• motorcycles, scooters;
• boats;
• trade, warehouse, industrial equipment;
• children's cars;
• wheelchairs.

Given the widespread use of 6 Volt batteries, they are produced in a wide range of capacities, they can have either 1.2Ah or 16Ah, or any value in between. Charging such batteries with a car charger is problematic. Close monitoring and constant adjustment of the current will be required. The risk of overheating is high.

The most suitable charger for a 6 Volt battery is the Imax B6 charger or similar. Current 10% of capacity, voltage up to 7.3V.

Charging lithium polymer batteries

Lipo 3.8 V are charged with the devices that come with them, or with chargers like the Imax B6.

The batteries are charged with current from 20 to 100% of the rated capacity. For batteries, smaller values ​​are preferable. The main question is, what voltage does a charged battery show? Having reached 70-80%, charging begins at constant voltage and decreasing current.

Special devices for Lipo 3.8 V signal the end of charging when reaching 70-80% capacity. A further increase in density ensures less frequent charging, but shortens the life of the battery as a whole.

When charging 3.8 Volt lithium polymer batteries, the charger should show 4.2 Volts. If you can set it to 4.1 Volts, it will take a little longer to charge, but the battery will last much longer.

Charging the battery without removing it from the car

The methods described above involve charging from a wall outlet, which usually requires removing the battery. However, charging can also occur under the hood. Modern portable devices, such as CTEK, have compact dimensions and allow you to charge a 12V battery under the hood. They can be left overnight so that the battery is in working order in the morning. Such chargers are especially relevant for car owners with calcium batteries.

Charging the battery with a generator

For vehicles with an engine internal combustion The battery works in conjunction with a generator. When traveling, the generator recharges the battery, which subsequently provides a charge to start the car.

If the battery capacity exceeds the recommended one, it will require significantly more time to charge from a standard generator. Often in such cases, the battery does not have time to recharge to the required level and begins to quickly discharge to the point of deep discharge.

When installing a battery with a capacity less than recommended, the generator current turns out to be too high for it, it quickly overheats and may boil.

The service life of the battery in both described cases is sharply reduced.

What voltage a charged battery should display depends largely on its type. We examined the main ones in detail. Gentle charging extends battery life. With timely maintenance, they can last up to 5 years or more.

Towards the end of autumn, motorists often have questions about how to properly charge their battery. How to do this to achieve the best result?

Lead batteries are charged from a source of “rectified” (direct) current. Any device that allows you to regulate the charging current or voltage is suitable for this, provided that it provides an increase in the charging voltage to 16.0-16.5 volts. Otherwise, it will not be possible to fully charge a modern 12-volt battery to 100 percent of its capacity.

To charge, the positive terminal of the charger is connected to the (+) terminal of the battery, and the negative terminal is connected to the (-) terminal.

There are two charging modes: constant current mode and constant voltage mode. These modes are equivalent in their impact on battery life.

Charging in constant current mode.

The battery is charged at a current of one tenth of the rated capacity after a twenty-hour discharge. That is, for a battery with a capacity of 60 A/h (amps per hour), a charging current of 6A is needed. The disadvantage of this charging mode is the need to repeatedly (every 1-2 hours) control the current value and regulate it, as well as the strong release of gases at the end of the process.

In order to reduce gas emissions and ensure a more fully charged battery, it is useful to gradually reduce the current as the charging voltage increases. When the voltage reaches 14.4 volts, the charging current must be reduced by half to 3 amperes (for a battery with a capacity of 60 A/h) and continue charging until gas evolution begins.

In modern batteries that are not equipped with holes for adding water, after increasing the charging voltage to 15 volts, it is useful to once again reduce the charging current by half - to 1.5 amperes (for a battery with a capacity of 60 A/h).

For so-called maintenance-free batteries, the state of full charge occurs at a voltage value of 16.3-16.4 volts (the difference depends on the quality of the electrolyte and the composition of the alloys from which the grids are made).

Charging in constant voltage mode.

With this method, the charge level of the battery at the end of the process depends on the amount of charging voltage supplied by the charger. So after continuous 24-hour charging at a voltage of 14.4 volts, a 12-volt battery will be charged to 75-85% of its capacity, at a voltage of 15 volts - up to 85-90%, and at 16 volts - up to 95-97 %. Completely within 20-24 hours. The battery is charged when a voltage of 16.3-16.4 volts is applied to it.

Depending on the capacity and internal resistance of the battery at the moment charging begins, the current passing through it can exceed 50 amperes. Therefore, in order to avoid its failure, the chargers limit the maximum current to 20-25 amperes.

During the charging process, the voltage at the battery terminals gradually reaches the value of the charger voltage, and the charging current decreases almost to zero (provided that the charging voltage is less than the voltage at which gas evolution begins). In this way, charging can be done without constant human attention. An indicator of the end of charging here is considered to be an increase in the voltage at the battery terminals to 14.3-14.5 volts. At this time, a green light signal usually turns on, indicating the moment the required voltage is reached and the charging process is completed.

In practice, for normal charging (up to 90-95% capacity) of maintenance-free batteries with modern chargers with a maximum voltage of 14.4-14.5 volts, a time of more than 24 hours is usually required.

Charging the battery on a car.

In a car, the battery is recharged at a constant voltage while the engine is running. By agreement with battery manufacturers, automakers set the charging voltage in generators to 13.8-14.3 volts - less than the voltage at which intense gas evolution occurs.

As air temperature decreases, it increases internal resistance battery, due to which the efficiency of its charging in constant voltage mode decreases. For this reason, it is not always possible to fully charge the battery on a car, and in winter when the voltage at the terminals is 13.9-14.3 volts and the lights are on high beam The battery charge does not exceed 70-75%. In this regard, in winter, in conditions low temperatures, short driving distances and frequent starts of a cold engine, it is useful to charge the battery indoors at least once a month using a charger.

Electrolyte density control.

For a newly charged battery, the density of the electrolyte in each jar should be in the range of 1.27-1.29 g/cm 3 . As the charge is consumed, the density gradually decreases and for a half-discharged battery it is 1.19-1.21 g/cm 3 . When fully discharged, the density of the electrolyte reaches 1.09-1.11 g/cm 3 .

A normally charged battery that does not have internal short circuits, the density of the electrolyte in all cans is approximately the same with a discrepancy of no more than 0.02 g/cm 3. If an internal short circuit occurs in any of the cans, the density of the electrolyte in it will be lower than in the others by 0.10-0.15 g/cm 3 .

The density of electrolyte and other liquids is measured with a device called a hydrometer. For various liquids, the hydrometer has interchangeable densitometers (from the Latin word densum - density, thickness, viscosity).

When measuring density, the hydrometer should, if possible, be held so that the float does not touch the wall of the tube. At the same time, the temperature of the electrolyte is measured, and the density is calculated on the basis that its temperature is +25°C. To do this, the hydrometer reading increases or decreases by a value taken from the table given in the relevant literature.

CLIMATE AND SEASONS WHEN MEASUREMENT ELECTROLYTE DENSITY		DENSITY (g/cm3)
		Battery charged	Battery discharged
			by 25%	by 50%
Very cold(temperature in January from -50°C to -30°C)	WINTER	1,30	1,26	1,22
	SUMMER	1,28	1,24	1,20
Cold(temperature in January from -30°C to -15°C)		1,28	1,24	1,20
Moderate(temperature in January from -15°C to -8°C)		1,28	1,24	1,20
Warm humid(temperature in January from 0°C to +4°C)		1,23	1,19	1,15
Hot dry(temperature in January from -15°C to +4°C)		1,23	1,19	1,15

If the operating cycle voltage on the battery is less than 12.6 volts and the electrolyte density is less than 1.24 g/cm 3, you should check the voltage at the terminals with the engine running and charge the battery.

By regularly performing these simple steps, you can achieve long-term and trouble-free battery operation at any time of the year.