How quickly does a car battery drain when idle?

Why does the car battery drain quickly when it is parked?

If the battery, fully charged the day before, suddenly refused to turn the starter, then keep in mind that a voracious consumer has entered the on-board network. Without the slightest idea about electricity, it is better to entrust its search to the service station masters. To avoid getting scammed, please note: a friendly technician will definitely ask a few questions about electrical equipment. For example, were the lights turned off at night, or was the radio changed? Well, those who are familiar with a multimeter can do it on their own, and the editors of Autostadt.su will tell you what and how.

Your car's battery suddenly runs out: are you sure you're not distracted?

A simple reason for losing all charge literally overnight could be elementary absent-mindedness. For example, when parking the car, the owner forgot to turn off the lights or the music. Therefore, rule No. 1 is to remember/check whether all electrical appliances connected bypassing the ignition switch were de-energized.

We recommend checking it out, especially if there are children in the family who are partial to the car. Sitting in the driver's seat as a child, there is a desire to twist everything that turns, including the buttons that turn on the consumers.

Well, and a cigarette lighter. It works in almost all cars, even when the keys are far from the ignition switch. This means that the navigator, recorder and other non-standard gadgets steal current from the battery when it is idle. Therefore, make it a habit to unplug all cords from the socket when parking your car for a long time.

Why did the new battery discharge to zero overnight after being installed in the car?

If you managed to blame everything on the old power source, then know that this is a grave mistake. Before replacing the battery with a new one, the owner is obliged to check the generator, leakage current, and diagnose the long-lived voltage. What should be the voltage on a car battery without load is the subject of the previous article.

Car radio. Trivial neglect of installation rules leads to high current consumption when switched off.
Signaling. Cheap equipment often malfunctions, and makeshift power supply negates the advantages of even reliable anti-theft models.

Are you confident in the impeccable competence of the installer of the new head unit? If not, then check the connection diagram of the car radio to the on-board electrical network. A classic mistake is to twist the control yellow and power red positive wires. In this situation, the battery is forced to power the radio processor even after it is turned off.

Is the wiring ok? Then study the typical reasons why a tape recorder exhibits increased appetite:

The output stage of the internal amplifier is active after switching off. As a result, the head unit “eats” about 1 A, and the manufacturer calmly attributes this fact to the design features. You can overcome this immodest need by integrating a disconnect button into the power supply wiring.
The external amplifier power control circuit is faulty. If there is one, then inspect the REM output. Using it, the car radio turns the amplifier on and off.
Radio malfunction. A short circuit and other troubles that may occur inside the head unit cannot be ruled out.

There are countless cars in which an abnormal alarm suddenly began to take on a life of its own. This is due to the “quality” of the equipment and its “good” connection to the on-board network. It’s best to find out what exactly is wrong with a private auto electrician. It could be a sensor or an incorrectly connected circuit.

Other reasons

The main note for gadget lovers: do not forget to turn off what you have connected.

This especially applies to the Bluetooth diagnostic scanner, which is connected to the OBD II port. Well, if you decide to open the factory wiring for the sake of installing, say, a radar detector, then remember - it is not recommended to power the equipment directly from “+”. Start at the ignition switch, build the fuse into the positive branch and there will be much fewer problems. It also happens that no one climbed anywhere, but the quiescent current increased sharply. This can be caused by a malfunction of any standard electrical equipment on board:

Short circuit in the window lift motor.
Bluetooth block.
Pilot systems for monitoring on-board electrical equipment with a single bus (if such a unit is on strike, then the symptoms are immediately visible - for example, some electrical device (headlights, etc.) turns on spontaneously).

How to find out the exact reason why your car battery drains quickly

It is necessary to move from assumptions to repair and adjustment work in tandem with a multimeter. This miracle device will indicate whether the current leakage exceeds the permissible figures. If yes, then with its help you can find out the exact reason why the battery discharges quickly when the car is stationary.

So, grab the multimeter, move the handle to the 200 mA position, remove the negative terminal, and place the probes in the gap between the wire and the battery negative. We fix the value.

Attention! The ignition must be turned off.

So, on a car without external signaling and music, the leakage current should be literally 70-80 mA.

Rejected? Then it’s not surprising that your car’s battery drains quickly. Rather, dive into the mounting block and pull the fuses one by one, while measuring the amperage. When the numbers drop noticeably, consider that the gluttonous chain has been found. If this is not observed, then the power circuits remain - the generator, starter and ignition system. First, inspect their contacts and wires. Oxidized terminals and poor insulation contribute to leakage.

Please note that we indicated the normal quiescent current for cars, as they say, from the assembly line. It’s hard to say how much the stuffed version should have. If only because some non-standard security systems in the “auto locked” state consume about 50 mA, while others consume 100 mA. If you want to see the quiescent current on a locked car, hold the hood switch and set the alarm to security mode.

Do not forget that driving short distances in traffic jams leads to chronic undercharging of the battery, especially in cold weather. From which one day the battery will be forced to give up the starter, requiring resuscitation from the mains charger. And not just any way! Each battery has its own charging technology: we have already explained what proper charging of an AGM battery and provided instructions for charging an EFB battery .

Doesn’t hold a charge: why does a car battery drain quickly when idle?

A defective radio, video recorder and alarm system powered in a makeshift way, a Bluetooth adapter forgotten in the diagnostic socket - all this can drain the battery to zero literally overnight. The situation will force you to throw the charger crocodiles on the “+” and “–” or use one of the models for rating portable starting chargers . But just waking up to take care of the battery is not enough. An integrated approach is needed.

Aging, undercharging and frost: why a car’s original battery discharges quickly after 3-5 years of use

Intensive discharge is usually attributed to the old battery, they say, it has served its intended period... The power source really does not last forever. Even in a state of rest and periodic recharging, it will serve faithfully for no more than 10 years. Approaching “death” is interpreted simply - the product has lost capacity.

What contributes to aging

You can explain from a scientific point of view why the battery quickly discharges and why it generally deteriorates using detailed theses:

Irreversible sulfation of plates. Lead sulfate, gradually sticking to the electrodes, reduces their active area, lowering the actual potential in A*h. This phenomenon is activated when stored in a discharged state or when the level of electrolyte in the jars is insufficient. Increasing the density of the electrolytic liquid, increasing its temperature and self-discharge contribute to this process.
Accelerated self-discharge. Globally, this is caused by dirt and dust accumulated on the box (the down conductors become shorted). Locally, this occurs in banks due to shedding of the active mass from the plates and destruction of the partitions between the electrodes. In new batteries, the process develops due to the presence of metal impurities in the separators, because metals are constantly split off and contribute to the flow of discharge currents.
Short circuit of positive and negative plates. This happens due to the coating falling off from them.
Destruction of positive electrodes in banks. This is the result of sloughing of the active mass and corrosion of the down conductors.
Cracks in the mastic and its peeling off from the plates during aging.

Constant undercharging

When the engine hums, the generator powers the vehicle's on-board equipment and battery. Priority is given to radios, headlights, heating and preheating, the remainder goes to the battery. Only experienced drivers add a voltmeter to the dashboard. And believe me, he is capable of terrifying. So, it is within his competence to explain why the car battery discharges quickly even after replacement:

At idle, figures of the order of 14.0-14.5 Volts are typical for an unloaded network. The beauty is that the generator is working properly and the battery is being restored successfully.
At XX with the lights and music on, the norm is 13.7-13.8 V. There are no comments on the “gene”, only the battery does not get enough current.

Long-term degradation is that chronic undercharging provokes sulfation. Over time, the battery begins to charge quickly and discharge just as quickly. The immediate effect is different. The battery simply does not restore capacity, but only wastes it. In city conditions this most often happens. To charge you need revolutions, but where can you get them in a traffic jam?

For your information . The energy expended by the starter to rotate the flywheel for 5 seconds is recovered from the generator in 20-30 minutes of continuous driving. The tachometer needle should not fall below 1,500 rpm.

You can directly encounter undercharging immediately after installing a new battery. A more capacious analogue attracts with an impressive A*h number on the label. In fact, the generator power is not enough to restore the charge to 100% within the usual time frame.

Frosty days

In cold weather, the battery loses capacity, causing discharge to occur faster. At temperatures below -15°C, a loss of 1 Ah per degree is completely normal. If you do not drive, the current source will run out and the electrolyte will freeze. Crystallization of the electrolytic liquid is dangerous because the body of the product may crack and the plates may become warped. The exception is AGM, in which the electrolyte is absorbed.

Current leaks: why even a new battery drains quickly when idle

The car radio, ECU and other equipment do not turn off completely. It goes into deep sleep mode and “eats” electricity even when the engine is turned off. In addition to them, there are active consumers in the form of an alarm system and an on-board control unit. The energy they consume when the ignition is off is called current leakage.

The total flow current at rest is no more than 50 mA. If everything is in good condition, the car’s battery will not run out in a week, or even a month of parking. You can check for leaks on any machine using a multimeter:

Disconnect the terminal from the battery.
Switch the tester to 10A measurement mode and connect the wires to the corresponding terminals on the device.
Touch the battery terminal with one probe, and the removed terminal with the other.

Attention! Work is carried out with the engine stopped and the on-board equipment turned off. 50 mA = 0.05 A.

If the value exceeds the specified value, we search for a “gluttonous” circuit. To do this, remove the fuses one by one and connect an ammeter instead. A serious consumer will be alerted to a jump in the device readings. The wiring of the multimedia system and alarm are at risk.

If you suspect a “head”, check out the characteristics of the device. It happens that the quiescent current of the amplifier is 1A. This appetite is due to the activity of the output stage even in the OFF position. The phenomenon is rare, but it does occur.

On a note . Remove the front panel of the radio and evaluate the quiescent current of the circuit. It will definitely be smaller, since in this position the player is completely de-energized.

Do not neglect the rules for installing a multimedia center. A typical mistake is to twist the yellow (control) and red (power) pluses. The low-current yellowish wire should connect to ACC+ on the ignition switch. Then the processor and memory of the device will be active only after turning the key.

What else should you do if the car battery loses an impressive current to power the rest of the audio system and therefore quickly discharges overnight? There are highly specialized problems here:

The REM output on the additional amplifier, through which the car radio controls its power supply, has failed.
One of the components inside the Hi-Fi device has shorted.
The fact of increased appetite has been noticed. You can install a button in the power circuit.

Signaling

When dealing with a “non-standard” signaling system, assessing it for the presence of “glitches” is goal No. 1. One of the symptoms is spontaneous unlocking/locking of doors. It is possible that the operation is correct, but one of the functions is not connected correctly. For example, auto start may not fully work due to the deactivated handbrake sensor, but the headlights or DRLs will turn on.

Possible problems with nutrition. To identify them, you can check the current leakage on a locked car:

Raise the hood.
Remove one of the terminals.
Connect the tester in ammeter mode (10A).
Pinch the hood position sensor.
Security the car using the key fob.
Take readings.

Third party equipment

Tips for properly powering the same DVR are written based on experience. Do not connect any unobtrusive device directly to “+”. Connect to the ignition switch and install a fuse in the circuit.

If the car is used, you need to check the main points, where the constant plus is usually taken from:

Interior lighting.
Cigarette lighter.
Positive battery terminal.

Another option is the ELM 327 adapter forgotten in the diagnostic socket. It consumes about 0.45 A, since it does not allow the ECU to go into sleep mode after turning off the ignition.

Glitches in standard systems

Each car has its own package of “surprises”. For example, the window lift motor may short out. From special cases - a Bluetooth unit or the head unit of a complete vehicle control system (sores of the Mitsubishi Outlander). Headlights turning on spontaneously is a very common complaint. Usually the dealer's flashing service helps out.

On a note

Daily discharges to zero kill the battery. It is better to prevent illness than to put up with the fact that the battery quickly loses its charge when driving a car. If a moment of intense discharge occurs, it is useful to identify it and refrain from cranking the starter again.

What to do to prevent the battery from draining quickly

Charging with a low current (about 1-2 A) prevents the initial sulfation of the plates. Connect the charger once a month at night and a regular battery will last 5-6 years without problems, and an AGM or EFB battery will last even longer.
Learn how to properly store your battery in the garage and at home. When parked in the cold for more than a day, remove the power source and bring it into a warm room (no more than +25°C).
Regularly clean the terminals on the car and the down conductors on the power source with a special brush for battery terminals (pictured) or a simple sandpaper. Oxides cause undercharging.

With the arrival of cold weather, recharge the product more often to 100% with normal current (10% of capacity).
Keep the outer surface of the battery clean. You can wipe with a 10% solution of ammonia and soda ash, then wipe dry.
If the battery is serviceable, clean the holes in the lids of the cans with a thin wire. Check the electrolyte level before charging. Standard: +10…15 mm from the safety shield. Compare the density of the electrolytic fluid with the voltage.
Periodically test the on-board network for current leaks.

How to find out if the battery is almost discharged

By load. methods for checking the battery upon purchase and ordinary observation are relevant

The starter barely turned the engine shaft.
When you turn on the heated seats/windows or headlights, the radio turns off.

Why does my car battery drain quickly?

The battery discharges quickly, which significantly complicates the process of operating the vehicle. After all, whether the driver can move unhindered depends on the performance of the power source. The battery is also used to power certain units and devices installed in the car.

Why does my battery drain quickly?

Experts identify 5 reasons why your car battery drains quickly. In order to correctly navigate and correct the situation, they must be studied in advance.

The battery life is completely exhausted

This is considered the most common reason why the battery in a car quickly runs out. This situation arises after 3-5 years, when the power source and its elements are worn out. After prolonged use, the battery loses not only its charge, but also its capacity.

The problems with lead acid batteries are related to the sulfation process. Its essence lies in the gradual accumulation of salts on the plates. This provokes a decrease in the working area at the terminals and deterioration of contact with the electrolytic composition.

In order to get rid of this problem, perform the following steps:

To prevent rapid battery discharge, a reduction in the number of short runs is required. After all, constantly starting the engine consumes a lot of energy. When moving a short distance, the expended energy is not fully restored.
The car battery is periodically charged using a charging unit. After all, the source deteriorates if it remains in a discharged state for a long time.
Deep discharge of the battery is prohibited. After all, this provokes a rapid loss of capacity and a reduction in working life.
Periodic check of electrolytic composition. Not only the composition level is monitored, but also the condition. Lead plates must be in an electrolytic composition.
Carrying out maintenance and prevention.

Such measures are effective for sources that have been in operation for 1-2 years. For a period of 3-4 years, a new battery is required.

Problems with the generator

It is not uncommon for a car battery to die because the generator is not functioning well. If the battery does not receive the required charge from the generator, it will be completely discharged within a short time after stopping.

What to do in this case? To test the functionality of the generator, use a multimeter. Next, the standard and additional equipment is launched. And only after that the voltage is established using a multimeter. Its value should be 13-14 V. If lower values are displayed on the multimeter monitor, then the required charge is not supplied to the source.

Reasons why the generator does not transfer charge to the battery:

The alternator belt has become deformed or broken.
Insufficient belt tension.
Violation of the integrity of electrical wiring and conductive contacts.
Poor functioning of the voltage regulator.
The diode bridge has failed.

To determine the exact cause of the deterioration in the performance of the generator and its elimination, specialists from a car service center are involved. Long-term use of a faulty generator leads to the fact that even a new battery is replaced.

Unacceptable temperature conditions

The question of why a vehicle battery is discharged often arises in winter. This is because the electrolytic composition becomes thicker at low temperatures. As a result, contact deteriorates.

In order to prevent such an outcome, the charge level of the car battery is monitored more carefully. To do this, evaluate the density of the electrolytic composition. There are tables online that give approximate values.

When operating vehicles in winter, follow the following rules:

You should not leave an uncharged battery.
The density of the electrolytic composition increases by 0.01-0.03 g/cm3.
The power supply is quickly supplied with a special case.
You should not leave the battery in the cold. Responsible drivers move the power source to a warm room.

Leakage current

Often the question of why the battery drains quickly also arises due to current losses. Current leaks occur due to:

Presence of oxides on conductive terminals.
Damage to the insulating layer, deterioration of electrical wiring.
Incorrect connection of electrical equipment.

Determination of leakage current is carried out in several stages:

Removing the ignition key.
Opening windows and closing doors. This is because the central locking is blocked while checking the power source.
Disabling equipment and devices that are connected to the electrical system.
Removing the negative conductive terminal.
Measuring leakage current using a multimeter.

The norm is 15-70 mA. If other parameters are displayed on the monitor, then you should involve a specialist.

What mistakes do drivers make?

Batteries run out due to the irresponsible attitude of drivers. Leaving the headlights and heating on all night leads to discharge.

You will have to correct the situation in domestic vehicles yourself. For new foreign cars, manufacturing companies have prepared devices that turn off headlights and heaters.

Reasons for battery discharge.

How to prevent battery drain?

To maintain a new or used battery in working condition, preventive measures are carried out.

1-2 times a year, the battery is recharged from a charger that is connected to the network. Experts recommend conducting training cycles.
After recharging the power source, check the density of the electrolytic composition and its level. Such actions are not performed if a maintenance-free device is installed in the vehicle.
Maintaining electrical wiring and devices in working order. Even minimal violations provoke current leakage and battery discharge.
Cleaning the battery case.
Cleaning terminals and other elements.

Causes of car battery boiling

Boiling of the power source provokes problems with electrical wiring and equipment, and starting the motor. If the battery gets very hot, then:

Lead plates and leads are gradually destroyed.
The likelihood of the lead plates shorting out and the source exploding increases.
Moving with a boiling power source provokes damage to wires and the vehicle body.
If the battery boils, the charging current also increases. This negatively affects the condition of the generator.

Why does my car battery boil?

1. Charging the battery at increased voltage and current

The result is overcharging of the power supply due to problems with the relay, which is designed to regulate the voltage.

The use of a current source for charging that is not regulated also leads to overcharging. This provokes a gradual boiling of the electrolytic composition, destruction of the plates, which should not be allowed.

Therefore, for recharging, drivers use only industrial-type chargers.

Occurs due to the fact that the battery is subjected to shaking and vibration. Gradually, the interplate zones are destroyed. The result is a short circuit and battery explosion.

Identifying a shorted power supply without testing is problematic. Therefore, novice drivers often use them. When a pulse is applied, the battery continues to heat up and the electrolyte boils.

To prevent this, inspections are recommended.

Plaque gradually forms on the lead plates that are part of the battery. It provokes a decrease in capacity, rapid discharge.

When charging the battery using a mains charger, the current increases. Therefore, the source can overheat and boil.

A dead battery cannot be recharged from a generator. After all, it can boil away.

4. Increasing load current

Simultaneous connection of several systems that consume energy leads to overload of the electrical network. If the used charge is not replenished, the battery heats up and the electrolyte boils.

Installing a battery in a vehicle that does not meet the standards leads to a reduction in technological and ventilation openings. The result is a boiled-out battery.

Boiling is also provoked by polarity reversal. After all, if the terminals are incorrectly positioned, large currents are supplied.

When the battery boils, perform the following actions:

Stop the engine and turn off the ignition.
Provide natural ventilation and open the hood.
Wait until the battery cools down.
Pour distilled water into the “jars” to increase the electrolyte level.
Check the voltage using a multimeter.

To prevent the boiling process, remove foreign objects from the power source. 1-2 times a month, check the condition of the electrolytic composition, voltage level, and evaluate the conductive terminals and housing.

Why buy a new battery when you can keep the old one in working condition? To do this, it is enough to follow a number of rules that have been tested in practice. It is periodically necessary to carry out preventive measures and maintenance of the battery, electrical devices, and wiring.

Video on the topic of fast battery discharge

Why does a car battery not hold a charge?

If a car engine is often compared to a heart, then the battery can be called a stomach, supplying the rest of the organs (that is, the components of the vehicle) with life-giving energy. The main part of the battery's work, taking into account energy costs, occurs when starting the engine. When it works, the generator takes over the functions of a source of electricity, but if its power is not enough to power all consumers, the battery comes to the rescue. Conversely, if the generator is not heavily loaded, the excess energy generated is used to recharge the battery. In principle, one average trip duration is enough to maintain the maximum charge level, but only if the battery is new and the on-board electrical circuit is fully operational. Alas, often one of these conditions is not met, and in this case a complete or partial discharge of the capacity is observed.

As a rule, battery aging is a process that extends over time, so the car owner has enough time to recognize the problem and prepare to solve it. But if the battery begins to drain abnormally quickly (for example, overnight or in a day), this is clear evidence that there is some external reason forcing it to give up its charge.

The most annoying thing is that such cases always happen unexpectedly and at the wrong moment, when the car is needed, but it is not possible to start it in the usual way.

It is impossible to say in advance whether it is possible to reanimate the battery. There are many reasons why a car battery discharges in just one night, and we will try to figure out how to correctly diagnose the current condition of the battery and what can be done to delay its death.

Why does the battery drain quickly?

A rapid discharge, especially on a new battery, is definitely an abnormal situation. And a similar problem can happen with the most expensive or budget product, since the reasons can be both internal and external.

Based on statistical data, an incomplete list of them, arranged in order of frequency of occurrence, will look like this:

The battery drains quickly due to its old age;
The battery does not charge while driving, or the charging current is insufficient;
there are current leaks in some part of the on-board electrical network;
the battery died due to electrical appliances not being turned off (multimedia center, heating, lighting);
leaving the car in the cold for a long time.

Let's consider the features of these factors.

Physical wear of the battery

Not only living beings, but also mechanisms are subject to aging. If we talk about the battery, this is the most common reason for losing the ability to hold a charge. The average service life of car batteries is 4-5 years. Old age can set in earlier if the battery is used intensively or if the manufacturer's recommendations are not followed. The fact that the battery will soon have to be replaced will be indicated by an ever-decreasing period between full discharges, which is accompanied by loss of capacity and sulfation of the plates.

This is an inevitable process - over time, lead sulfate, which is a by-product of chemical reactions, settles on the plates, gradually reducing the area of the active mass responsible for generating electricity through chemical interaction with the electrolyte.

Approximately in the fourth year of operation, the battery charge decreases by 30-40% of the nominal value, and this can already cause difficulty starting the power unit, especially in winter, at subzero temperatures.

To delay the onset of old age, you can put into practice the following simple techniques:

try to reduce engine starts to a minimum - if possible, let it run for a few minutes at idle speed rather than overload the battery;
remember that to restore the electrolyte capacity you will need to travel at least 10 kilometers. Otherwise, the battery will remain undercharged, and if you practice this every day, one day you simply will not be able to start your car. So try to avoid short trips, they are not enough to maintain the battery charge at the nominal level;
If you are not sure whether your car battery is sufficiently charged during your trips, periodically charge the device from the network using a charger. Even a partially discharged state is harmful for the battery, since in this case the rate of sulfation increases;
Deep discharge of the battery is considered even more harmful. For example, when you make multiple unsuccessful attempts to start the power unit. Maintenance-free calcium batteries suffer especially badly. This is also one of the common reasons why a car’s battery drains literally overnight, although everything was fine the day before;
check the electrolyte level as often as the engine oil level - this will allow you to notice in time the exposed plates that are being destroyed by exposure to air, and add the right amount of fluid;
Carry out work related to the prevention of plate sulfation at least once a year.

However, for 4-5 year old batteries, such measures may be ineffective, since they have already served their purpose. No resuscitation measures will help in this case, except for purchasing a new device. By the way, it is better not to throw away the old battery, since now there is a trade-in program - you hand over a non-working battery and purchase a new one at a discount.

The generator does not provide charging

This problem is much less common, but it can affect the battery regardless of its age and current condition. In this case, a long trip will not be beneficial, since the battery will not charge, but will give up its energy. As a result, in the morning you will probably experience problems starting the engine.

The difficulty is that without instrumental measurements, only a very experienced car owner can understand that the generator is not able to provide the required charge, and even then not immediately.

Meanwhile, a multimeter is enough for such a check. The procedure itself is also simple:

start the engine;
at idle we turn on as many consumers as possible - headlights, radio, heated rear window and/or seats;
measure the voltage level at the battery terminals. The nominal value is 12.014.4 V.

A lower value indicates that the above problem exists, and the battery charge level will gradually decrease until it is completely discharged. If the voltage level is higher than the specified value, this will cause activation of the hydrolysis process, as a result of which water will intensively evaporate from the electrolyte.

Undercharging from the generator can be caused by the following reasons:

during operation, the alternator belt lost its integrity;
the belt may simply loosen and slip;
The generator voltage regulator does not function;
there is damage to the electrical wiring in the area between the generator and the battery;
The diode bridge has failed.

If, as a result of measurements, you find that the battery on your car quickly runs out due to the fact that the generator does not provide its normal charging, you should look for the cause and eliminate it - otherwise you will soon have to part with the battery, as with all subsequent ones.

Leakage current

Another common reason why your car battery can die overnight. Most often it appears on cars with a significant mileage. Current leakage is akin to a consumer that is always on, so a quick and causeless discharge of the battery should alert you.

In order to make sure that this is where the problem lies, you need to take the appropriate measurements using a universal multimeter. This is done like this:

with the ignition key removed, provide access to the interior if the doors are locked with the central locking (you can, for example, fully open the front windows);
make sure that all consumers are disconnected from the power supply, including when the ignition is turned off;
lift the hood and disconnect the negative terminal from the battery;
connect the multimeter connectors to the disconnected terminal and the negative pole;
turn on the device to measure the leakage current. The nominal value is in the range of 15.0-70.0 mA.

If the leakage current is greater, you should look for the location where the problem exists. It can be:

worn wires with characteristic damage to the insulation layer;
oxidized contacts;
incorrect connection of new or installed after repair electrical appliances.

Loss of electrolyte rated performance

Rapid discharge can be caused by a decrease in the density of the electrolyte, as well as evaporation of water due to excessive charging provided by the generator.

Both problems can be solved, but provided that you monitor the condition of the battery and, if necessary, carry out maintenance activities.

In particular, the electrolyte level can be checked by unscrewing the filler plugs. The normal value is approximately 1-1.5 centimeters above the level of the electrodes.

Boiling of water can occur not only during recharging - this phenomenon is also typical for hot weather, at extremely high air temperatures.

The density of the electrolyte is also measured quite simply - by dipping a hydrometer into the liquid. If it is higher than normal, you should dilute the electrolyte by adding a small amount of distilled water (you can buy it at any pharmacy).

If the electrolyte level is normal, the battery is charged, but the density is low, in order to correct the situation, you will have to tinker. To do this, use a small rubber bulb with a long tip to remove a small amount of old electrolyte and fill in a new one instead. After waiting some time to allow the electrolyte to mix and settle, repeat density measurements are taken. If it lies within 1.27÷1.29 grams/cubic. cm, the procedure should be considered completed. Otherwise, we repeat the process until the desired result is achieved.

The battery is shorting

The cause of a battery short circuit may lie either in the plane of improper operating conditions of the battery, or due to the presence of a manufacturing defect.

A short circuit occurs when battery plates of different polarities begin to touch. This happens for the following reasons:

as a result of warping of the lattice of plates,
if the separator begins to collapse;
when a growth appears on the electrodes, increasing in size over time;
when sludge accumulates at the bottom of the battery case, reaching the plates;
if a foreign object gets into the battery during its maintenance.

It is not difficult to recognize a short circuit: in this case, the electrolyte begins to boil quite intensely, which leads to a drop in voltage at the battery terminals. At the same time, the capacity of the car battery is reduced accordingly.

In old-style batteries that had a serviceable housing, a short circuit was not an irreparable problem. The electrodes and the can were cleaned, and the faulty element was simply replaced with a new one.

In modern devices, such operations cannot be performed.

There is a method for eliminating short circuits for maintenance-free batteries. It consists of passing a large current through the plates, which burns out the contact points of the electrodes, destroying them. The disadvantage of this procedure is the need for special equipment and appropriate skills, that is, for most car owners this option is unacceptable. In this case, there is only one way out - installing a new battery.

Unsuitable operating conditions

We are talking about those cars that are parked in open areas in winter, in severe frost. In principle, negative temperatures are bad for any battery, since the electrolyte capacity depends on temperature. This dependence is especially strong if the thermometer drops below minus 15°C. In this case, each degree below this value provokes a decrease in battery capacity by 1 mAh. And if the battery is completely discharged, there is a risk of electrolyte freezing.

That is why it is recommended to store the battery in a heated room during severe frosts.

It is also important in winter to constantly monitor the state of charge of the car battery by measuring the density of the electrolyte.

We provide a table from which you can evaluate the relationship between the freezing temperature of the liquid and other parameters of the electrolyte and battery:

The story of how the alarm system drained its battery

It would seem that modern hybrid (Ca/Sb) and calcium (Ca/Ca) batteries are practically protected from self-discharge. This means that a car with such a battery is insured against failure to start after a long period of inactivity. Whatever the case! Even a serviceable battery in the warm season can be completely discharged while the car is in “standby mode”. We'll talk about the reasons below.

Insidious electronics

A modern car is literally crammed with electronics. On-board computer, radio, alarm, various sensors and regulators (for example, door closing sensor). Each of these consumers, at first glance, needs crumbs of energy, and certainly cannot discharge the battery. How is it really going?

The car alarm is permanently connected. Otherwise, either the battery will be removed, or even stolen for spare parts, to those regions where the “swallow” will no longer be found. How much does the signaling system consume per day? Let's calculate in ampere hours, although it is correct to indicate consumption in watts. It’s just that A/h is an established and constant unit for all systems with 12-volt batteries. So, the alarm system consumes about 2 A/h per day. With a working antenna - about 2.7 A/h. Thus, twenty days or a month is enough for a static “signal” alone to drain a fully charged battery. And if the siren went off, even less.

Everything is clear with the alarm system, but what about the other consumers? The on-board computer, even with the engine turned off, in rest mode, continues to “pull” charging. The same story with the radio turned off, if the panel is not removed. In total, only these two devices are capable of “robbing” a battery by 0.2 A/h per day - much less than an alarm, but still significant.

An incompletely closed door, a malfunctioning voltage regulator, leaks due to damaged wiring - all this can finally “drink the juice” from the poor “Akebashka”. Add to this the increased self-discharge of the battery in winter, the possible loss of energy from the resistance at the oxidized terminals... As you can see, it is not at all difficult to find yourself with a completely discharged battery after a long period of inactivity.

How to make sure it doesn't run out?

A few simple rules will help:

If necessity forces you to leave your car for a month or more without the supervision of vigilant neighbors, or even far from home, do not skimp on reliable parking, and there you can already disconnect the terminals from the battery (first “minus”, then “plus”). The method, of course, is “square-nest”, but you will definitely be able to drive the car after it has been idle for a long time.
Do not try to recharge the battery by setting the car to autostart. At first glance, it should keep the battery in good shape. But this is not true: starting the engine is extremely energy-intensive. After starting, the internal combustion engine will spin the generator for about twenty minutes, and to compensate for the lost currents, the engine needs an hour of idling. Conclusion: a waste of both fuel and battery power.
Set up the alarm so that it does not react to every rustle. The less it turns on from all sorts of little things, the less energy it will “gobble up”.
Check the wear and tear of the power source if you are using a stand-alone alarm system . A battery built into the “alarm” can drain the battery under the hood quite a lot.
Some alarms have a “parking” mode. If you activate it, battery losses will be minimized. If there is none, and disconnecting the battery is scary, you can simply turn off the shock sensor.
And, of course, keep an eye on the health of your battery and electrical equipment. Almost all cases of emergency “death” of the battery are associated either with a short circuit to the car body due to damage to the wiring, or due to a malfunction of the battery/charging sensor.