Car enthusiasts quite often encounter the problem of battery discharge. For reasons unknown to many car owners, the battery can be discharged in a matter of days. And even long trips do not fully charge the battery. Let's consider the possible reasons for battery discharge:
Old battery
90% of batteries on the Russian market are maintenance-free, so a “load plug” (a special device for testing battery power) is perhaps the only tool with which an auto electrician can check the performance of a battery. If the problem of battery discharge is an exhausted resource, then further diagnostics electrical system no car required. The service life of maintenance-free batteries is usually no more than three years. In other cases, the battery can be reanimated by replacing the electrolyte, flushing the battery and then charging. Also, rapid battery wear can be caused by climates with sudden temperature changes. In the climatic conditions of Russia, such fluctuations exceed seventy degrees, which is detrimental to any battery, regardless of its cost and country of origin.
In case of battery failure, it may well help. An auto electrician will either help you get to your destination, or replace the battery with a new one at the site of the breakdown.
Signaling
The cause of battery discharge can be car alarms, especially satellite ones. If the car is not used, the satellite alarm will drain any battery within two weeks. Also create problems with fast discharge The battery may be due to an incorrectly installed alarm system. In such cases, the anti-theft system is dismantled by an auto electrician to further check the electrical circuit. An experienced electrician will quickly determine where the current leak is occurring. If diagnostics reveal that the alarm system itself has defects, then it is most advisable to replace it with a new one. Nowadays, many car services offer to repair faulty car alarms, but such an offer must be accepted carefully and only from trusted car repair shops. Otherwise, you may be disappointed a second time. The most common case after car alarm repair is a radio frequency failure, the consequence of which is the loss of the signal, and, accordingly, the alarm control.
If you have problems with your car alarm - you can’t turn it on/off, get into the car or start the engine, no need to rush and order a service. You should first consult with a technical assistance specialist - perhaps the fault can actually be fixed on the spot, saving time, money and nerves.
Non-original speaker systems
When tuning car audio, rarely does anyone think about the colossal load of installed acoustics on all electrical components of the car. A standard car audio tuning kit includes: a storage device, an amplifier, a subwoofer, a radio, sometimes a TV, a set of speakers, sometimes a TV and copper wiring that can withstand the power of a full-fledged power plant. With such a set of generated energy there is simply not enough, the generator is not able to supply the car with the required amount of electricity, as a result of which the battery discharges. When installing speaker systems, it is better to consult with an experienced auto electrician, since with the help of small mathematical calculations you can determine what load your generator will withstand, or solve the problem by installing a more powerful generator and an additional battery.
Auto repairmen do not carry out such work on site, but offer to order a tow truck to transport the car to the workshop.
Generator
Generator failure is one of the most common reasons rapid discharge of the battery, and this trouble is not amenable to statistics and can overtake you when leaving the car dealership in a newly purchased car. This cause of discharge is usually determined only after diagnosing the vehicle's electrical wiring. Don't be too upset about a generator failure. This damage is not that significant. The generator can be repaired, bought a similar used one, or purchased a new one at the nearest specialized auto parts store. The most common cause of generator failure is the failure of the voltage regulator relay. Quite often, the graphite brushes on generators wear out, in some cases the bearings break, and the diode bridge fails. This can happen even on a new car due to faulty wiring.
Repairing a generator is, in most cases, a service job, so in such situations, the dispatcher of the on-site technical assistance service, as a rule, offers to transport the faulty car on a tow truck to a car repair shop.
Malfunction of electrical components
In rare cases, a breakdown related to the car’s electrical system cannot be found immediately. Modern cars have a complex electrical wiring system, and troubleshooting can take days. Very often, some electronic elements that work in conjunction with similar ones, but are responsible for completely different functions, fail, and if one fails, not so important element, all others responsible for the entire electronics of the car may fail. Sometimes such a breakdown is especially difficult to find. Many auto electricians have had to deal with the simple oxidation of just one contact located on the engine control unit, but blocking the entire operation of the car. In such cases, computer diagnostics of the car are powerless and the fault must be identified visually and repaired manually. If there is a need for auto electrical repairs, it is better to contact professional technicians who have been specializing in such work for several years.
On most cars, standard electrical breakdowns occur, accompanied by the same malfunctions, and in the case of a common breakdown, almost any professional auto electrician who comes to the call can make a diagnosis in a matter of minutes with further elimination of the problem or an offer to transport the car on a tow truck to a car service center, if troubleshooting requires conditions auto repair shop and service equipment.
The battery is one of the most insidious sources of problems in a car. The suspension will warn you in advance about its breakdown, the engine will burn oil, the wheel hubs will buzz, and so on. But the battery usually “gets sick” suddenly. It would seem that it started up just yesterday, but today it doesn’t. The battery itself does not always need to be blamed for this; it is often hostage to a combination of circumstances or mistakes of the car owner. Our task is to understand where these circumstances and errors come from.
Battery age
But the first reason is still related to the battery. Everything, including batteries, has its own service life. It is difficult to predict how long a battery will last; for some they “die” in 2-3 years, for others they can last for ten years. On average, today 5-6 years is considered normal. Battery aging is understandable from a chemical point of view. At this age, the battery begins to be particularly affected by a process called sulfation. Simply put, this is the accumulation of lead sulfate on the plates, due to which the “working” area of the plates is reduced and the battery capacity decreases. It is believed that in old age the battery loses up to a third of its former capacity. And if so, then you can recharge it even every day, by the next morning there will still not be enough charge.
It is impossible to completely overcome the overgrowth of plates with lead; this process is inevitable, but you can influence its speed by following the operating recommendations.
1. Avoid short runs. Of course, when you have a car, it’s stupid to put its “needs” above your own, but there is nothing extraordinary in avoiding frequent starts and short trips whenever possible. If you need to go to a store 500 meters from your home, is it really necessary to go there by car? To start the engine you will spend batteries, which then it will not be able to replenish from the generator due to a very short operating time. The more often you repeat this, the more the battery plates become overgrown with lead.
2. Avoid deep discharges. This is already 100% the driver’s fault. I forgot to turn off the headlights, the tape recorder and even the emergency lights (if for a long time) and the battery was discharged to zero. This in itself is a cause of discharge and an excellent catalyst for sulfation. Of course, the battery can be recharged, and it will still work, maybe even work for a long time, but its potential resource has already been damaged. Especially if the battery is maintenance-free.
3. Avoid long periods of downtime. The optimal mode for a battery is when it is used more or less regularly, but downtime almost inevitably leads to discharge and sulfation. If for some reason it is not possible to operate the car, then you can simply periodically recharge the battery in the network charger. This will avoid discharge.
4. For owners, maintenance batteries need to be checked regularly amount of electrolyte and add it as needed to prevent contact of the plates with air.
This is advice for the future, so to speak, but is it possible to do something if the battery plates are already overgrown with lead? Can. The operation is called desulfation. For owners of serviced batteries, both chemical and electrical methods are available. The chemical method is based on the use of the drug Trilon B and is very simple - you need to pour the old electrolyte out of the jars, pour in the Trilon B solution, wait an hour, drain the solution, rinse a couple of times with distilled water, and pour in fresh electrolyte. Trilon B makes insoluble metal salts soluble, so lead is literally washed off from the plates - the battery capacity is restored. Trilon B itself costs about 300 rubles per 500 grams of powder, is highly soluble in water and can be useful in the automotive industry not only for desulfation - it is also used to flush the cooling system. If you have a serviceable battery, this is a real and inexpensive way to extend its life.
If the battery is maintenance-free, then all that remains is to use the electrical method, which is based on charge-discharge cycles. The process is very simple, but takes a lot of time. You need to charge the battery with a weak current, approximately 0.8-1 ampere and a voltage of 14 volts. Charging lasts 8 hours, after which there is a break for 12 hours. Then charging again, but with a current of 2-2.5 amperes. And again a break. Now the battery needs to be discharged - significantly, but not to zero. A high beam lamp turned on for 6-8 hours is good for this purpose. Then the procedure needs to be repeated 2-3 times, you can control the amount by voltage. The battery capacity should then increase. Sometimes everything takes up to two weeks, especially if you have another battery and you can drive a car with another battery.
Of course, there are special devices that can operate in charge-discharge mode, without manipulating the lamp, but they themselves are expensive - around 7,000 rubles, it’s cheaper to buy a new battery. It pays off only if there are many cars in the family or with long-term use.
Problems with battery charging
One more possible reason It is not related to the battery itself, but to the vehicle’s electrical system. If the battery is not recharged properly, it will not last long. Normal is at least 13 volts with consumers turned on. If it is less, then you need to look for the reason. We have already devoted a lot of material to this topic, in which we outlined possible generator breakdowns and methods for repairing it. In order not to repeat ourselves, we will simply provide a link to.
Leakage current
Another insidious point that can creep up suddenly. It seems that the battery is new, and the charging is excellent, but the car will still turn into “real estate” if the current runs out while the car is stationary. There is always a small expense for clocks, alarms and other equipment, the viability of which must be maintained even when the ignition is turned off. Another question is the size of the leak.
If you suddenly find a car with an “empty” battery, and there seems to be nothing to indicate this, then we’ll get it checked. It's easy to do.
1. On a car with the ignition off, turn off all obvious consumers (headlights, tape recorder, ...).
2. Remove the negative terminal from the battery.
3. Using a multimeter in current measurement mode, we measure between the battery negative and the terminal.
If the resulting value is less than 70 mA, then you don’t have to worry about the leak, but if it’s more, then you need to look for the culprit and the cause. It’s easier to deal with the culprit; there is one tricky way - keep the multimeter turned on between the terminal and the “minus” of the battery, ask a friend to pull out the fuses one by one. In theory, removing one of the fuses should sharply reduce the value on the multimeter dial. All that remains is to use the reference book to determine what exactly this fuse is responsible for.
The cause of the leak is more difficult, even if there is an understanding of who is causing it. The reasons are usually divided into two parts - poor connection and problems in the device itself. The terminals could oxidize, the wire insulation could be damaged, or unsoldered strands could crumble. The consumer may have a short circuit or a problem with setup and control. In most modern cars, when the ignition is turned on, the current supply to consumers stops, however, additional equipment (music, alarms, rear view cameras) is often mounted with a direct connection. Yes, this is convenient during operation (you can listen to the same music without a key in the ignition, but it leads to problems if the “counterparty” starts acting up. So you need to deal with leaks, firstly, by checking and changing the wiring to the problematic unit, -secondly, diagnosing him himself.
Switched on electrical appliance
A fairly obvious reason, but for the sake of completeness it cannot be ignored - if you forget to turn off the headlights, or leave the car for a long time with the hazard lights or multimedia system on, then the battery was somehow not healthy, it will still be discharged. Here the driver can only fight his own absent-mindedness. If this does not help, install a relay with automatic shutdown using a timer.
Temperature conditions
Finally, it might just be cold. It is estimated that when the temperature drops by 1 degree, the capacity drops by 1 mAh, at night at -30°C and below, even young and full of energy The battery may not survive. If you need to go somewhere in the morning, then it’s better not to tempt fate and take the battery to a warmer place for the night. If low frosts are a feature of your region, then there is another option - buy or sew a special case yourself with which you can cover the battery (alternatively, use). This, of course, is not a panacea, but even the heat that the case retains may be enough so that the battery does not discharge so quickly.
According to statistics, the battery life on models last generations increased. If previously batteries rarely survived more than three or four years, today many car owners talk about five, seven and even nine years of operation. But for this, the car owner himself needs to be careful - to operate the car correctly, not to allow a discharge due to his mistakes, and to promptly respond to breakdowns of “adjacent” devices - the generator or consumers. Then there is practically no chance that the battery will suddenly discharge.
I leave the house in the morning, press the central locking button and... nothing. The car does not respond. No problem, we open it with the key. We turn the ignition key, but the lights don’t even light up, there’s a slight squeak from under the panel. Everything is clear - the battery is dead. Even if everything was fine yesterday, due to a number of reasons, the battery can be discharged in just one night. Most often, this violation is detected only in the morning, and leads to being late for work.
The consequences of such a situation can be extremely disastrous: the plates can crumble irreversibly. If this happens in the cold, the electrolyte may freeze and expand, damaging the battery case.
Reasons for rapid battery discharge
A dead battery in the morning is a consequence of an emergency situation. If the car battery is discharged to zero, it means that a fairly high power consumer was turned on.
How to find the reason
The algorithm of actions when searching for a problem depends on the urgency and the need for further movement.
Attention! To save time and cash When making diagnostics, use the rule from simple to complex, from cheap to expensive. For example, there is no need to change an expensive generator if the cause of the discharge is damaged wiring.
First, you need to visually inspect the ignition switch, battery and alternator, as well as all visible wiring. What to pay attention to:
If nothing critical is found, you can “light it” from another car or install a known-charged battery. When connecting wires, pay attention to the spark. A jumping spark indicates current consumption, which should not exist when the ignition is turned off. Often this is precisely the reason why the car battery quickly discharges.
Checking the operation of the generator
A separate point needs to be placed on the operation of the generator. 
If there is no spark, start the car and check the operation of the generator. Apply the gas, if the belt makes a whistle, you need to tighten it. If everything is in order with the belt, we turn on all electrical consumers - headlights, lights, fan, and so on.
Lastly, turn on the wiper blades and monitor their speed. With increased energy consumption, a non-working generator is not able to provide energy to the wipers - they will move noticeably slower than usual. The voltage at the battery terminals will also be low - less than 12.8 volts. If this is the case, the cause of the dead battery should be associated with a malfunction of the generator.
A faulty generator cannot provide the car with electricity, this is one of the reasons why even a new battery in a car quickly discharges.
Looking for a current leak
Current leakage in a car is determined using an ammeter. It is found in most modern multimeters. We will need a measurement range from 0 to 20 Amps. 
- We put a known-good charged battery in the car, connect the negative terminal, and connect the ammeter to the gap between the positive wire and the battery terminal.
- If the readings are higher than 0.2 - 0.4 amperes (there are always constant consumers - computer, clock, alarm, radio), then there is a current leak.
- We are looking for an unauthorized consumer by turning off the fuses. If the numbers on the ammeter drop when the fuse is removed, then there is a breakdown in this circuit.
- Disturbances in the wiring occur due to soured starter solenoids, a shorted temperature sensor on the radiator, or a short circuit in the generator windings.
- Damage to the generator field wire inside the braid can cause the generator to be excited and draw a lot of current.
If no current leakage is observed, it is worth analyzing the operation of the alarm. It is constantly connected to the battery and is the most likely current consumer.
Can the alarm drain the battery?
Standard alarm consumes 0.08 ampere/hour. Complex alarms with remote notification waste 30% more. This is not much; a 60 Amp/hour battery will discharge after about a month of inactivity. 
The alarm works like this: when armed, it goes into “sleep” mode. Current consumption is minimal. When a contact in the sensor circuit is closed, the unit is triggered, sending a signal to the headlights and siren, as well as an alert to the key fob. Modern alarms are able to respond to loud sounds, vibrations and even excessive proximity to the car. Such systems consume more current because they use the radar principle or photocells.
Reasons why alarms consume more current.
- Presence of a radio warning module. It requires more energy to operate than the alarm itself.
- Marriage signaling schemes.
- Incorrectly installed or too sensitive sensors The alarm goes off; if the siren is broken, this leads to an increased discharge.
- Immobilizer activation. In this case, the battery will work, but the ignition will not turn on.
- Faulty autostart tried to start the engine. The starter quickly drains the battery.
- The autonomous type alarm system has its own battery. If it wears out, the relay tries to charge it and “pulls” energy from the main one. Therefore, it is better to install a dependent alarm or check the battery of the main one.
Attention! Install and repair alarms in a specialized workshop from an experienced auto electrician. Incorrect connections or exposed wires may cause fire or serious damage.
It is quite difficult to check the serviceability of the alarm, since the discharge may be short in time and impossible to track. The test is simple:
- The alarm is turned off and the car is operated without it. If the battery does not discharge, it is worth diagnosing or installing a new unit.
- The hood rises, the sensor end is clamped. We measure the alarm current consumption. We provoke accidents - we knock on the fenders, we shake the car. The alarm consumes more current during activation, but after set time should turn off and not consume unnecessary energy. If the alarm does not turn off, it can easily “drink” an entire battery overnight.
Useful video
This video clearly shows how to determine why the battery discharges overnight:
Conclusion
To avoid unpleasant moments in the morning, you should take care of your car. This applies not only appearance or the cleanliness of the interior, first of all you need to periodically undergo maintenance, carefully monitor extraneous noises, look under the hood. The battery and generator brushes are consumables that need to be changed in accordance with technical regulations. Outside interference in the car's wiring, installation of low-quality alarm systems with “crooked” hands are generally dangerous and can cause a fire.
Operate your car correctly, study the life of a motorist, and you won’t have such problems in the morning.
Of course, the battery is one of the most important parts of the car. With the help of the battery, which powers the starter, the engine starts and the generator is supported if it cannot cope with the load. In addition, a working battery ensures the operation of the central locking system, alarm system, headlights and other components powered by electricity. Modern car batteries are designed for an average service life of 3–5 years, after which most of them become unusable. Very often the battery can be discharged in very important life situations.
For blondes: this is what a car battery looks like
Appearance of the battery on Lifan Solano: reverse polarity
No matter how powerful and high-quality the battery is, sooner or later it will weak points will appear. Therefore, you should not be surprised that after several years of use, the battery in the car will discharge overnight. There are several good reasons for this:
- The battery has completed its full cycle.
- The engine does not charge.
- There is a current leakage ().
- Electrical appliances in cars are constantly turned on even when the engine is turned off.
- The battery closes ().
Also one more probable cause discharge is that the car is parked with the engine turned off in the cold for a long time. If the battery is discharged for this reason, it must be taken into a warm room and allowed to warm up, after which it can be charged and used further.
If it’s winter outside, then this material will be useful to you:
How to tell if your battery is dead
To avoid getting into an awkward and even dangerous situation when the battery dies in the middle of the road, you need to carefully monitor the condition of the battery. It is recommended to check the electrolyte density level at least once every three months. This service will be provided by any car service that has a hydrometer, a special device similar to a pipette with a float and scale, which is needed to measure the density of the electrolyte.
So, a charged battery has a density of at least 1.12 g/ml, a half-charged battery has a density of 1.2 g/ml to 1.15 g/ml, a fully discharged battery has a density of electrolytes of 1.28 g/ml .
If a car has a maintenance-free battery, manufacturers install a special warning lamp. When the battery is charged, the lamp lights up green. A red light from the lamp will indicate that the battery is low.
How to open a car with a dead battery
But what to do if the battery is already discharged? If the lock does not respond to signals from the remote control, then only a regular car key and the lock cylinder can save you.
It often happens that the battery runs out in a car with electronic key. If the battery is dead and there is no way to get into the cabin, then there is no need to panic.
Ask other drivers for permission to use their battery.
The easiest way is to find a ready-made charged battery and several wires 1 to 2 meters long. After this, the car must be placed on a jack so that part of the crater protection can be removed.
You need to independently connect the plus to the most positive terminal of the starter and generator, and the negative wire to any other part that runs on electricity. After connection and successful installation of all wiring, it is recommended to open the car only with the key fob.
How to jumpstart a dead battery from another car
If it is not possible and time to charge the battery in the car in the traditional way, you can start the car using the cigarette lighter. This method is popularly called “lighting”. To “light up” you need to place two cars with the hood facing each other. Next, you need to connect the batteries of both cars in parallel (plus-plus, minus-minus). After this, you need to light the engine of the other car and wait about 10 minutes so that the dead battery is charged, at least for a short time. After this operation, you can start the car with a newly charged battery.
Start the engine using towing
This method of starting the engine with a discharged battery is suitable only for those cars with a manual transmission.
Towing: one of the most common ways to start a car in an emergency
To charge the battery in a car using a tow, you need to perform some actions: the car accelerates in neutral gear, after which you need to turn on the ignition and press the clutch. When the engine is started, you need to depress the clutch, disengage the gear and stop towing a little.
Old battery: what to do?
If the battery has been in use for more than five years, then it is likely that with the onset of the first frosts, interruptions in the operation of the battery will begin. If the battery is completely discharged in the cold, it is better to immediately go for diagnostics.
If the old battery is classified as serviceable, then it can be “reanimated” by adding electrolyte and charging the battery.
Battery leakage
When the battery discharges overnight, you need to check why this is happening. It is not difficult to determine that there is still a current leak if you know basic physics and basic skills in working with an ammeter. It is much more difficult to find the exact location of the area where the leak is observed.
To do this, you need to remove the negative terminal from the battery and use an ammeter to measure the current between the negative terminal of the battery and the removed terminal. If the ammeter shows that the leakage level is above 80 mA, then this is a very big problem and at the same time a signal to everyone that it is necessary to do maintenance for a long time.
Forgotten appliances left on
It often happens that when you turn off the engine, you automatically forget that you also need to turn off the side lights, the radio, and other devices.
Electrical consumers with their constant operation lead to the fact that the battery begins to discharge at a rapid pace. If this is an unfortunate exception rather than an unfortunate rule, there is nothing irreparable in this regard. To restore the battery's performance, you just need to recharge it so that it works in its usual mode again.
