In the practice of motorists, two methods of charging a battery (battery) are used - with a constant charging current and with a constant charging voltage. Each of the methods used has its own advantages and disadvantages, and the battery charging time is determined by a combination of factors. Before you start charging a new battery, just bought, or a discharged battery removed from the vehicle, it must be carefully prepared for charging.
In a new battery, it is necessary to fill in the electrolyte of a regulated density to the required level. With the battery removed from the vehicle, it is necessary to clean the oxidized terminals from dirt. The case of a maintenance-free battery should be wiped with a rag moistened with a solution of soda ash (better) or baking soda, or diluted ammonia.
If the battery is serviceable (battery banks are equipped with plugs for filling and topping up the electrolyte), then it is necessary to additionally thoroughly clean the top cover (with screwed plugs) so that when the plugs are unscrewed, no accidental dirt gets into the electrolyte. This will certainly lead to battery failure. After cleaning, you can turn out the plugs and measure the level and density of the electrolyte.
If necessary, add electrolyte or distilled water to the required level. The choice between adding electrolyte or water is based on the measured density of the electrolyte in the battery. After topping up the liquid, leave the plugs open so that the battery “breathes” during charging and does not burst with the gases released during charging. Also, through the filler holes, you will have to periodically check the temperature of the electrolyte in order to avoid overheating and boiling.
Next, connect a charger (charger) to the output contacts of the battery with the indispensable observance of the polarity (“plus” and “minus”). At the same time, the “crocodiles” of the charger wires are first connected to the battery terminals, then the power cord is connected to the mains, and only after that the charger is turned on. This is done to prevent the ignition of the oxygen-hydrogen mixture released from the battery or its explosion during sparking at the moment the crocodiles are connected.
For the same purpose, the procedure for disconnecting the battery is reversed: first, the memory is turned off, and only then the “crocodiles” are disconnected. An oxygen-hydrogen mixture is formed as a result of the combination of hydrogen released during battery operation with atmospheric oxygen.
Charging the battery with direct current
Under direct current in this case is understood the constancy of the magnitude of the charging current. This method is the most common of the two used. The temperature of the electrolyte in the battery prepared for charging should not reach 35 °C. The charging current of a new or discharged battery in amperes is set equal to 10% of its capacity in ampere-hours (example: with a capacity of 60 Ah, a current of 6 A is set). This current will either be automatically maintained by the charger, or it will have to be regulated by a switch on the charger panel or by a rheostat.
When charging, you should control the voltage at the output terminals of the battery, it will increase during charging, and when it reaches the value of 2.4 V for each bank (i.e. 14.4 V for the entire battery), the charging current should be halved for a new battery and two or three times for used. With this current, the battery is charged up to abundant gas formation in all battery banks. Two-stage charging allows you to speed up battery charging and reduce the intensity of gas emission that destroys the battery plates.
If the battery is slightly discharged, it is quite possible to charge it in a single-stage mode with a current equal to 10% of the battery capacity. A sign of the completion of charging is also abundant gas evolution. There are additional signs of the completion of the charge:
- invariability of electrolyte density within 3 hours;
- the voltage at the battery terminals reaches the value of 2.5-2.7 V per section (or 15.0-16.2 V for the battery as a whole) and this voltage remains unchanged for 3 hours.
To control the charging process, it is necessary to check the density, level and temperature of the electrolyte in the battery banks every 2-3 hours. The temperature should not rise above 45 °C. If the temperature limit value is exceeded, either stop charging for a while and wait for the electrolyte temperature to drop to 30-35 °C, then continue charging at the same current, or reduce the charging current by 2 times.
Based on the state of a new uncharged battery, its charge can last up to 20-25 hours. The charge time of a battery that has had time to work depends on the degree of destruction of its plates, the operating time and the degree of discharge, and can reach 14-16 hours or more when the battery is deeply discharged.
Charging the battery with constant voltage
In constant charge voltage mode, it is recommended to charge maintenance-free batteries. To do this, the voltage at the output terminals of the battery should not exceed 14.4 V, and the charge is completed when the charge current drops below 0.2 A. Charging the battery in this mode requires a charger maintaining a constant output voltage of 13.8-14.4 V.
In this mode, the charge current is not regulated, but the charger is set automatically depending on the degree of battery discharge (as well as electrolyte temperature, etc.). With a constant charging voltage of 13.8-14.4 V, the battery can be charged in any of its states without the risk of excessive gassing and overheating of the electrolyte. Even in the case of a completely discharged battery, the charge current does not exceed the value of its nominal capacity.
At a non-negative electrolyte temperature, the battery is charged up to 50-60% of its capacity in the first hour of charging, by another 15-20% in the second hour, and only by 6-8% in the third hour. In total, in 4-5 hours of charging, the battery is charged to 90-95% of its full capacity, although the charging time may be different. Signs of the completion of the charge are a decrease in the charging current below 0.2 A.
This method does not allow you to charge the battery to 100% of its capacity, since for this it is necessary to increase the voltage at the battery terminals (and, accordingly, the output voltage of the charger) to 16.2 A. This method has the following advantages:
- the battery charges faster than constant current charging;
- the method is easier to implement in practice, since there is no need to regulate the current during charging, in addition, the battery can be charged without removing it from the vehicle.
When the battery is used in a car, it is also charged in the constant charge voltage mode (which is provided by the car generator). In "field" conditions, it is possible to charge a "planted" battery from the mains of another car by agreement with its owner. In this case, the load will be lower than with the traditional method of "lighting up". The time of such a charge, necessary for the ability to start on its own, depends on the temperature of the environment and the depth of discharge of its own battery.
Charging requires not only a completely dead battery (it is not desirable to bring it to this point), but also a battery that is in operation. But recharge time they will have miscellaneous. Often this from 8 to 12 hours. Our online calculator will help how much to charge a car battery using direct current.
The first charge of a new (uncharged) battery can take a relatively long time: 25–50 hours (depending on the condition of the battery). How long a used battery takes to charge depends on its state of discharge, usage time and condition. A heavily discharged battery may take 14-16 hours or more.
When, how and with what current to charge
As a rule, the degree of charge of the battery is judged by the density of its electrolyte. The density of a fully charged battery should be 1.26-1.28 g / cm³, the voltage should be at least 12.5 V. Everything will depend on whether it was originally installed in a new battery in your region of residence, it can be either 12.7 V or 12 .9V. The lower the density, the more it is discharged. A decrease in density by 0.01 g/cm3 compared to the nominal one means that the battery is discharged by about 6-8%. The degree of charge must be determined by the bank with the lowest density.
| Charge degree (%) | Electrolyte density (g/cm³) | Discharge degree (%) | Battery voltage (V) | Charge time at 10% capacity (hours) |
|---|---|---|---|---|
| 100 | 1,277 | 0 | 12,73 | Not necessary |
| 90 | 1,258 | 10 | 12,62 | 2 |
| 80 | 1,238 | 20 | 12,50 | 4 |
| 70 | 1,217 | 30 | 12,37 | 6 |
| 60 | 1,195 | 40 | 12,24 | 8 |
| 50 | 1,172 | 50 | 12,10 | 10 |
| 40 | 1,148 | 60 | 11,96 | 13 |
| 30 | 1,124 | 70 | 11,81 | 16 |
| 20 | 1,098 | 80 | 11,66 | 20 |
| 10 | 1,073 | 90 | 11,51 | 24 |
| 0 | 1,06 | 100 | 11,4 | Sulfation |
A lead-acid battery that is more than 50% discharged in summer and only more than 25% in winter needs to be removed and recharged. Also, additional charging is required by the battery, the density in the banks of which differs by more than 0.02 g / cm³.
The optimal battery charging current is considered to be current equal to 0.05 from its capacity ( equalizing charge). So for a battery with a capacity of 55 Ah, this value is 2.75 A, and for 60 Ah it is already 3 amperes. The purpose of this method is to ensure complete recovery of active masses in all battery plates.
An equalizing charge is able to neutralize the effects of deep discharges. Recommended for the elimination of electrode sulfation caused by long-term operation of the battery at a charge of less than 70%.
Although the so-called forced charge and take another ratio - 10% of capacity. That is a standard car battery 55Ah charge current 2.75-5.5A, and for 60Ah battery charging current is set within from 3A to 6A. But, you need to know that the smaller the charging current, the deeper the charge, although it takes more time. Exactly the same situation with the supplied voltage - the more the faster, but it should not fall below 13.8 And exceed 14.5V). The charging voltage is raised up to 16.0-16.5V only when charging a maintenance-free battery.
Applying current above 1/10 of its capacity is harmful, but even below 1/20 will be useless when charging.
It should be noted that today there are several methods for recharging the battery:
- With direct current;
- At constant voltage;
- Combining in automatic mode (we will not consider it, since in this case the time calculator is not needed).
Stages of discharge of a car battery
Battery charging time at constant current
The formula for calculating the charging current is: I \u003d Q * k, where Q is the battery capacity, and k is a certain coefficient from the nominal value (its ideal value is in the range of 0.04 ... 0.06, and the optimal value is up to 0.1). Based on this recommendation, the calculation of the time it takes for a fully planted battery looks like this: T \u003d Q / I. Substituting your values, you will see that it takes a lot of time, but since it often does not require a full charge, but only the restoration of the lost capacity, then this figure will be two or one and a half times less.
For a rough estimate of the required time to charge a car battery direct current first you need to determine the degree of discharge of the battery (in percent), then determine the lost capacity (in Ah), and then, choosing the amount of charging current, calculate the time for full charge. The formula for calculating how long it takes to recharge a car battery looks like this:
Multiplying this ratio by 2 times is necessary due to the fact that the efficiency of the process is 40-50%, the rest is spent on heating, as well as related electrochemical processes.
The use of the calculation formula must necessarily be accompanied by monitoring the progress of the charging process, especially at its completion, so as not to miss the onset of rapid boiling.
When for an hour at the battery terminals, during charging, the voltage stops increasing, the battery is 100% charged.
The value of the final voltage depends on: the value of the charging current, temperature, internal resistance of the battery, the presence of impurities in the electrolyte and the composition of the lattice alloy.
How to use the calculator
To find out how long you need to charge your battery, you do not need to go into the details of all processes and calculation formulas, just use this calculator.
For online calculation, you must fill in all three fields:
- In the "Nominal capacity" field, enter the capacity of the rechargeable car battery.
- In the "Degree of discharge" field, you can enter both the percentage calculated from the table and the voltage measured with a voltmeter.
- In the "Charging current" cell, you need to specify what kind of current you plan to charge the battery from the charger.
In winter, topics related to car batteries are especially relevant, because a cold start can quickly discharge it. Many change old batteries (), buy new ones (the main thing) - however, most try to recharge them and use them further. Fortunately, modern batteries run for a long time (about 4 - 5 years), but this period can be much reduced! If you apply current incorrectly and calculate the wrong charge time, the battery can quickly fail. Therefore, today the detailed information is how long it takes to charge your battery ...
I would like to make a reservation right away - with a special charger, at an approximate temperature of 25 degrees Celsius, this is important, because if the temperature exceeds 35 degrees, then it is better not to start the process (here is the dependence of the temperature of the electrolyte and the ambient air)! The thing is that the electrolyte has a different density at different temperatures (by the way, you can see -). However, I propose to recall the principles of charge and discharge.
The principle of the battery
In order to charge it, you need to understand how it works - no, I will not decompose it into various components now, everyone already knows what the lead plates are inside. We need to understand - what is, for example - 55 Amp * hour and 12 Volts.
- Amp and clock – measured in ampere/hours. That is, if your battery (battery) is 60 Ah, then it can deliver 60 amperes for one hour. Accordingly, if the load drops, for example, to 30A, then it can already give two hours and so on. I think this is understandable.
- Voltage - it is generally accepted that the voltage is 12 volts, although this is not entirely correct. The normal value of the working option is 12.6 - 12.7V (there are options with more), this is 100% fully charged.
If the voltage is 12V, then we can state that the battery discharge is about 40 - 50%, but you can drive with such indicators. If your car is working properly and the generator gives a normal "charge", then the voltage will quickly recover. I would also like to note that an indicator of 11.5 - 11.6V indicates "", this is very "unpleasant" for the battery. The process of “sulfation” of lead plates inside begins, which simply reduces the capacity of the battery - it can be so much that the car simply does not start.
That is, we understand that normal indicators are 12.7V (charged), it is with this voltage that 60 amperes will be given for an hour, and then it will drop to 11.6V (discharged). Then charge and re-use.
Two battery structures
This is also an important line, the whole point is that you need to charge each of the types in different ways, or rather prepare for the charging process. SO:
First type These are the so-called maintenance-free batteries. Which have an electrolyte inside and it is, as it were, “sealed” inside, that is, it cannot evaporate. If it turns into steam, it further condenses on the walls and re-falls into the main electrolyte. This is the most trouble free type. No need to worry about level replenishment, density, etc.
Second type - (which is a thing of the past) - serviced. It does not have a sealed case, so the electrolyte (or rather the water from it) can evaporate, thereby lowering the level. This option is one of the most problematic, you need to be able to take care of it and charge it! For example, if the level is lowered, charging should not be done! You need the right preparation.
Battery preparation
Before charging the battery, it must be properly prepared, because if you remove it, then you need to check everything at once. As I wrote above, we will talk about a serviced battery.
- First you need to remove all condensation, oxide and dirt from the surface and contacts. To do this, simply take an ordinary rag, soak it in a solution of ordinary soda and wipe the upper part - the contacts. Thus, we achieve purity - this is important! After all, if your battery has screw caps on top, then dirt can get into them during dismantling - which is highly undesirable! After all, it can be the cause of battery failure, simply.
- You can open the covers. We check the electrolyte level, if it is extremely low - it does not close the plates, then it is necessary - MANDATORY, to add distilled water. Otherwise, you will simply "kill" your battery. Lead plates will heat up and crumble.
- Ideally, you need to measure the density of the electrolyte. Let me remind you for a working, normal battery, it is - 1.26 - 1.30 g / cm3.
After the preparatory work, you can proceed to charging. However, it is worth noting - that it comes in two versions - using direct current and using constant voltage, the time can vary greatly from these parameters. Unless of course you have a universal charger, there you have a minimum of settings.
DC charge time
I think it’s not worth explaining that you connect the negative terminal of the battery to the minus of the “charger” with the plus in the same way. Many adhere to this particular option, because the “Amperage” that we apply to the battery is a very important parameter - in no case should it be exceeded, and if it is greatly underestimated, the battery will take a long time to charge.
I also want to warn you that the voltage should be greater than the nominal voltage - that is, we get about 13.8 - 14V from the charger, about the same amount gives a car generator. Only then will the charge go, if the voltage is less than 12 (and even more so 11V), then nothing will happen, but most likely it will further aggravate the discharge.
SO : The optimal voltage is 10% of the total battery capacity, that is, if you have 75 Ah, then you need to charge with a current of 7.5A.
Thus - if your battery is completely discharged (voltage less than 11.7V), then it should recharge in 10 hours! However, the time may be shortened by the discharge level.
In the variant with a serviced battery, it is quite easy to determine this - as soon as bubbles appear from the surface of the electrolyte in the banks, this means that the charge has completely taken place.
From myself I want to add - in ancient times (about 20 years ago), my father very often charged the battery at home, especially in winter. He set the current to 2A on the 60Ah option and left it overnight, so the battery took the right amount of energy from this small current. It should be noted that the discharge was then not deep. Therefore, if you just want to “energize” your battery, for example, the voltage at the contacts is exactly 12V, set it to a current of 1 - 2A at night!
However, now there is another way that also requires a minimum of human intervention.
Constant voltage charging time
This option is gaining more and more popularity - it is this principle that is implemented on many Chinese devices, where there are practically no “VOLTAGE” and “AMPERAGE” indicators, but only luminous “dots” or a scale that signals the charge. Such a device is designed specifically for maintenance-free batteries, because you will not be able to watch the boiling of the electrolyte and the release of gas from it, because everything is sealed. Therefore, the first option is not very good. Voltage and amperage are automatically adjusted here.
SO A: The voltage can float between 13.8 and 14.5V, the higher the voltage, the faster the charge.
So in the first hour, the battery can absorb from 50 to 60% of the nominal capacity. THEN, if it is 60A, then 60X60% = 36A
In the second hour - the voltage drops, and the charge is slower, about 15 - 20%
The third hour is even lower, about 7 - 8%
Fourth - almost full capacity of 90 - 96%.
The next hours are not really needed, the current strength can “fall” to 0.2A, charging to 100% will take almost the same 10 hours.
During engine operation, the battery (), regardless of type (serviced or maintenance-free battery), is recharged from the car generator. To control the battery charge on the generator, a device called a relay-regulator is installed.
The very operation of the car in winter often involves short trips, the inclusion of a large number of energy-intensive equipment (heating mirrors, windows, seats, etc.). The load on the battery increases significantly. At the same time, the battery simply does not have time to charge from the generator and compensate for the losses spent on launches. In view of the foregoing, it is optimal to fully charge the battery with a charger up to 100% at least once a year before the onset of cold weather.
We add that in case of problems with starting the engine due to engine malfunctions (problems with fuel equipment, etc.), the owner has to turn the starter much longer and more intensively. In such cases, you will need to charge the battery with an external charger much more often.
Charging the battery with a charger
To know how to charge a maintenance-free car battery with a charger, as well as to charge a serviceable type battery, you must follow certain rules. The charger (charger, external charger, start charger) is actually a capacitor charger.
A car battery is a direct current source. When connecting the battery, be sure to observe the polarity. For this, the connection points for the plus and minus terminals are marked with a plus and minus sign ("+" and "-") on the battery. The terminals on the charger have the same markings, which allows you to correctly connect the battery to the charger. In other words, the “plus” of the battery is connected to the “+” terminal of the charger, the “minus” on the battery is connected to the “-” output of the charger.
Please note that an accidental polarity reversal will cause the battery to discharge instead of charging. It should also be taken into account that a deep discharge (the battery is completely planted) can in some cases disable the battery, as a result of which it may not be possible to charge such a battery using a charger.
It should also be borne in mind that before connecting to the charger, the battery must be removed from the car and thoroughly cleaned of possible contamination. Acid drips are well removed with a damp rag, which is wetted in a solution with soda. To prepare the solution, 15-20 grams of soda is enough for 150-200 grams of water. The presence of acid will be indicated by the foaming of the specified solution when applied to the battery case.
As for serviced batteries, the plugs on the "cans" for pouring acid should be unscrewed. The fact is that during charging, gases are formed in the battery, which must be provided with a free exit. The electrolyte level should also be checked. When the level drops below the norm, distilled water is topped up.
What voltage to charge a car battery
To begin with, charging the battery involves supplying it with such a current that the battery does not have enough for a full charge. Based on this statement, it is possible to answer the questions of how much current to charge the car battery, as well as how much to charge the car battery with a charger.
In the event that a battery with a capacity of 50 Amp-hours is 50% charged, then at the initial stage, a charging current of 25 A should be set, after which this current should be dynamically reduced. By the time the battery is fully charged, the current supply should stop. This principle of operation underlies automatic chargers, with the help of which a car battery is charged in an average of 4-6 hours. The only disadvantage of such memory is their high cost.
It is also worth highlighting semi-automatic type chargers and solutions that involve fully manual configuration. The latter are the most affordable and widely available for sale. Considering that the battery is usually 50% discharged, you can calculate how much to charge a maintenance-free car battery, as well as understand how much to charge the battery of a serviced type of car.
The basis for calculating the battery charge time is the battery capacity. Knowing this parameter, the charge time is calculated quite simply. If the battery has a capacity of 50 Ah, then for a full charge it is required to supply a current of no more than 30 Ah to such a battery. 3A is set on the charger, which will take ten hours to fully charge the battery with the charger.
In order to be 100% sure that the battery is fully charged, after 10 hours you can set the current to 0.5 A on the charger, and then continue charging the battery for another 5-10 hours. This method of charging does not pose a danger to car batteries, which have a large capacity. The downside can be considered the need to charge the battery for about a day.
To save time and quickly charge the battery, you can set it to 8 A charger, and then charge for about 3 hours. After this period, the charge current decreases to 6 A and the battery is charged with this current for another 1 hour. As a result, it will take 4 hours to charge. Note that this charging mode is not optimal, since it is desirable to charge the battery with a small current of up to 3 A.
Charging at high currents can overcharge and overheat the battery, resulting in a significantly shortened battery life. We also note that the use of battery charging methods that are aimed at minimizing the negative process of plate sulfation do not have noticeable positive results in practice.
Proper operation of the battery, depending on its type (serviced and maintenance-free), the exclusion of deep discharge and timely charging with the help of a charger, allow the acid battery to work properly from 3-7 years.
How to assess the condition and charge of a car battery
Proper charging and a number of conditions that must be observed during the operation of a car battery can ensure normal engine start even at extremely low temperatures. The main indicator of the state of the battery is the degree of its charge. Next, we will answer how to know if the car battery is charged.
To begin with, some battery models have a special color indicator on the battery itself, which indicates whether the battery is charged or discharged. It should be noted that this indicator is a very approximate indicator, according to which it is possible to determine with a certain degree of probability only the need for recharging. In other words, the charge indicator can show that the battery is charged, but at the same time, the starting current at low temperatures is not enough.
Another way to determine the degree of charge of the battery is to measure the voltage at the battery terminals. This method also allows a very approximate assessment of the state and degree of charge. To measure the battery, you will need to remove it from the car or disconnect it from the charger, after which you need to wait an additional 7 hours. The outside temperature is not of fundamental importance.
- 12.8V-100% charge;
- 12.6V-75% charge;
- 12.2V-50% charge;
- 12.0V-25% charge;
- A voltage drop of less than 11.8 V indicates a complete discharge of the battery.
You can also check the battery level without waiting. To do this, the voltage at the battery terminals must be measured by the load using the so-called load plugs. This method is more accurate and reliable. The specified plug is a voltmeter, a resistance is connected in parallel with the terminals of the voltmeter. The resistance value is 0.018-0.020 Ohm for a battery with a capacity rating of 40-60 Amp-hours.
The plug must be connected to the corresponding outputs on the battery, after which, after 6-8 seconds. record the readings displayed by the voltmeter. Next, you can evaluate the degree of charge of the battery by voltage using a load plug:
- 10.5 V - 100% charge;
- 9.9 V - 75% charge;
- 9.3 V - 50% charge;
- 8.7 V - 25% charge;
- Indicator less than 8.18 V - full discharge of the battery;
You can also take measurements in the absence of a load plug without removing the battery from the car. The battery must be connected to the vehicle's on-board network. Then you will need to put a load on the battery by turning on the dimensions and high beam of the head optics (for cars with standard halogen lamps). The headlight bulbs have a power of 50 W, the load is about 10 A. The voltage of a normally charged battery in this case should be about 11.2 V.
The next way to check the battery charge is to measure the voltage at the battery terminals at the moment when the internal combustion engine is started. These measurements can be considered reliable only under the condition of a normally working starter.
At the time of starting, the voltage indicator should not be lower than 9.5 V. A voltage drop below the specified mark means that the battery is very discharged. In this case, it needs to be charged with a charger. This test method also allows you to identify problems with the starter. A knowingly serviceable and 100% charged battery is installed on the car, after which a measurement is made. If the voltage at the battery terminals at the time of starting drops below 9.5 V, then problems with the starter are obvious.
Finally, we add that measurements in various ways involve fixing fluctuations in fractions of a volt. For this reason, increased requirements are put forward for the voltmeter. The accuracy of the device is extremely important, since the slightest error of even one or two percent will lead to an error in measuring the degree of charge of the battery by 10 -20%. For measurements, it is recommended to use instruments with a minimum error.
How to charge a completely dead car battery
A common cause of deep battery discharge is banal inattention. It is often enough to leave the car with the dimensions or headlights, interior lighting or radio on for 6-12 hours, after which the battery is completely discharged. For this reason, many car owners are interested in the question of whether it is possible to restore a completely discharged battery.
As you know, the complete discharge of the battery greatly affects the life of the battery, especially when it comes to a maintenance-free battery. Manufacturers of car batteries indicate that even one full discharge is enough for the battery to fail. In practice, relatively new batteries can be restored at least 1 or 2 times after they are completely discharged without a significant loss of operational properties.
First you need to determine how much the battery is discharged using one of the above methods. You can also immediately put the battery on charge. Further, a completely discharged battery must be charged in the mode recommended by the battery manufacturer. The standard is to supply a charge current value of 0.1 of the total battery capacity.
A fully planted battery is charged with this current for at least 14-16 hours. For example, consider charging a battery with a capacity of 60 Ah. In this case, the charge current should be between 3 A (slower) and 6 A (faster) on average. It is correct to charge a fully discharged car battery with the smallest current, and for as long as possible (about a day).
When the voltage at the battery terminals no longer increases within 60 minutes. (assuming the same charging current is supplied), then the battery is fully charged. Maintenance-free batteries when fully charged assume a voltage value of 16.2 ± 0.1 V. It should be borne in mind that this voltage value is a standard, but there is a dependence on the battery capacity indicator, charge current, electrolyte density in the battery, etc. Any voltmeter is suitable for measurement, regardless of the error of the device, since it is necessary to measure a constant, not an exact voltage.
How to charge a car battery if there is no charger
The easiest way to charge the battery is to start the car by "lighting up" from another car, after which you need to drive the car for about 20-30 minutes. For the efficiency of charging from the generator, either a dynamic ride in high gears or movement in the “lower classes” is assumed.
The main condition is to maintain the crankshaft speed at around 2900-3200 rpm. At the specified speed, the generator will provide the necessary current, which will allow you to recharge the battery. Note that this method is only suitable under the condition of a partial, and not a deep discharge of the battery. Also, after the trip, you still need to realize a full battery charge.
Quite often, motorists are interested in what else can charge a car battery, except for the charger. Most often, as a replacement, it is supposed to use chargers that charge mobile phones, tablets, laptops and other gadgets. We note right away that these solutions do not allow charging a car battery without a series of manipulations.
The fact is that the main condition for supplying current from the charger to the battery is that there must be a voltage at the charger output that will be greater than the voltage at the battery outputs. In other words, with a battery output voltage of 12 V, the charger output voltage should be 14 V. As for various devices, their battery voltage often does not exceed 7.0 V. Now imagine that you have a gadget charger at hand that has the required voltage of 12 Q. The problem will still be present, since the resistance of the car battery is measured in whole ohms.
It turns out that connecting charging from a mobile device to the battery outputs will actually be a short circuit of the outputs of the charging power supply. The protection will trip in the unit, as a result of which such a charger will not supply current to the battery. In the absence of protection, the probability of failure of the power supply from a significant load is high.
It is worth adding that the car battery should also not be charged from various power supplies that have a suitable output voltage, but they are structurally unable to adjust the amount of current supplied. Only a special charger for a car battery is a device that has at its output the required voltage and current to charge the battery. In parallel with this, it is possible to control a constant current value.
Homemade charger for car battery
Now let's move from theory to practice. Let's start with the fact that you can make a battery charger from a power supply from a third-party device with your own hands.
Please note that these actions represent a certain danger and are performed solely at your own peril and risk. The administration of the resource does not bear any responsibility, the information is presented for informational purposes only!
There are several ways to make memory. Let's take a quick look at the most common:
- Making a charger from a source that has a voltage of about 13-14 V at its output, and is also capable of providing a current of more than 1 Ampere. For this task, a laptop power supply is suitable.
- Charging from a regular household electrical outlet 220 volts. To do this, you need the presence of a semiconductor diode and an incandescent lamp, which are connected in series in a circuit.
It should be borne in mind that the use of such solutions means charging the battery through a current source. As a result, constant monitoring of the time and the end of the battery charge is required. This control is carried out by regularly measuring the voltage at the battery terminals or by counting the time for which the battery is charged.
Remember, overcharging the battery leads to an increase in the temperature inside the battery and the active release of hydrogen and oxygen. Boiling of the electrolyte in the "banks" of the battery causes the formation of an explosive mixture. If an electric spark or other sources of ignition are present, the battery may explode. Such an explosion can cause fires, burns and injury!
Now let's focus on the most common method of self-manufacturing a charger for a car battery. We are talking about charging from a laptop power supply. To implement the task, certain knowledge, skills and experience in the field of assembling simple electrical circuits are required. Otherwise, the best solution would be to contact specialists, purchase a ready-made charger or replace the battery with a new one.
The scheme for manufacturing the memory itself is quite simple. A ballast lamp is connected to the PSU, and the outputs of a home-made charger are connected to the battery outputs. As a "ballast" you will need a lamp with a small rating.
If you try to connect the PSU to the battery without using a ballast bulb in the electrical circuit, then you can quickly disable both the power supply itself and the battery.
You should step by step select the desired lamp, starting with the minimum ratings. To begin with, you can connect a low-power turn signal lamp, then a more powerful turn signal lamp, etc. Each lamp should be tested separately by connecting to a circuit. If the light is on, then you can proceed to connecting an analogue that is larger in power. This method will help not to damage the power supply. Finally, we add that the burning of a ballast lamp will indicate the charge of the battery from such a home-made device. In other words, if the battery is charging, then the lamp will be on, even if very dimly.
A new battery must be fully charged and functional, that is, it must be immediately installed on the car to start further operation. Before purchasing, it is necessary to check the battery for a number of parameters:
- body integrity;
- voltage measurement at the outputs;
- electrolyte density check;
- date of manufacture of the battery;
At the initial stage, it is necessary to remove the protective film and inspect the case for cracks, drips and other defects. In case of detection of the slightest deviations from the norm, it is recommended to replace the battery.
Then the voltage is measured at the terminals of the new battery. You can measure the voltage with a voltmeter, while the accuracy of the device does not matter. The voltage should not be lower than 12 volts. A voltage reading of 10.8 volts indicates that the battery is completely discharged. Such an indicator is unacceptable for a new battery.
The density of the electrolyte is measured using a special plug. Also, the density parameter indirectly indicates the battery charge level. The final stage of the test is to determine the release date of the battery. Batteries that were released 6 months. ago or more from the day of the planned purchase should not be purchased. The fact is that a ready-to-use battery has a tendency to self-discharge. For this reason, for long-term storage, the battery must be prepared in advance, but in this case, the battery can no longer be considered a new finished product.
It turns out that the answer to the question of whether it is necessary to charge a new battery for a car will be negative. There is no need to charge a new battery. If the battery you plan to buy is dead, then it may simply be old, used, or there is a manufacturing defect.
Other Questions Regarding Car Battery Charging
Very often, during operation, owners try to charge the battery without removing the battery from the car. In other words, the battery is charged without removing the terminals directly on the car, that is, the charging battery remains connected to the vehicle's network.
Please note that when charging the battery, the voltage indicator at the battery terminals can be around 16 V. This voltage indicator strongly depends on what type of charger is used when charging. We add that even turning off the ignition and removing the key from the lock does not mean that all devices in the car are de-energized. The security system or alarm system, head multimedia device, interior lighting and other solutions can remain switched on or be in standby mode.
Charging the battery without removing and disconnecting the terminals may result in too high voltage being supplied to the powered devices. The result is usually a breakdown of such devices. If your car has devices that cannot be completely de-energized after the ignition is turned off, then it is forbidden to charge the battery without disconnecting the terminals. Before charging, in this case, it is necessary to make a mandatory disconnection of the "negative" terminal.
Also, do not start disconnecting the battery from the "positive" terminal. The "minus" terminal on the battery is connected to the car's electrical network through a direct connection to the body. An attempt to turn off the "plus" first can have sad consequences. Inadvertent contact of a wrench or other tool with metal parts of the vehicle body/engine will result in a short circuit. This situation is quite common in those cases when, with the help of keys, the positive terminal is unscrewed from the battery terminal with the minus not removed.
As for charging the battery in the cold or indoors in winter without heating, the battery can be safely recharged in such conditions. During charging, the battery heats up, the temperature of the electrolyte in the "banks" will be positive. In parallel with this, it is required to bring the battery into heat for charging if the electrolyte inside the battery has frozen and the battery has been completely planted. It is necessary to charge such a battery strictly after the thawing of the frozen electrolyte occurs.
Everyone knows that the battery is charged from the car's alternator during operation. But sometimes this charge is not enough. Any battery needs to be recharged if its charge level has dropped by 50% in the summer, and by 25% in the winter.
The question of the required amount of time is relevant all the time. Car owners want to know the exact numbers so that they can plan their upcoming trips. But the unequivocal answer to the question "how much?" does not exist.
There are a lot of nuances on which the time spent on charging a car battery depends. First of all, you need to pay attention to what kind of battery is used in the car.
In order to properly charge the battery, you need to determine what type it belongs to. The most common now maintenance-free batteries. They are easier to use, as they do not require additional manipulations to control the electrolyte level.
The maintenance-free battery has a sealed case with no openings for adding distillate.
Serviced batteries, although they are a thing of the past, are still found. Their peculiarity is that for proper operation, it is periodically necessary to add distilled water to the electrolyte. For this, there are special openings with covers on the case.
Both types of batteries require periodic recharging. One make-up from a car generator is usually not enough for them, especially in winter. Therefore, in order not to remain a pedestrian, the car owner needs a charger.
Experts recommend! The Vympel-68 starter charger will be an excellent assistant for a car enthusiast. It is designed both to help the battery in starting the car, and to fully charge the battery. For emergency start, just connect the device to the car's cigarette lighter.
How to prepare the battery before charging?
Before you start charging your car battery, you need to prepare it.
Clean the case and output contacts from dirt and acid. This can be done with a soft cloth dipped in soda solution. Make sure that the solution does not get into the battery banks.
Carefully unscrew the caps and check the electrolyte level. If required, add distilled water. You don't need to close them. One has only to cover the holes with them, so that when boiling, the electrolyte does not splatter everything around.
When connecting the charger to the battery terminals, the polarity must be observed. The sequence is also important: first, the charger is connected to the battery, and only after that it is connected to the network.
Charging should take place in a well-ventilated area. If you charge the battery directly in the car, the hood must be open.
Important! If you have removed the battery in winter from a car that is frozen, do not start charging it immediately. The battery must be thawed and only after the battery has warmed up is it possible to prepare and charge.
How to charge the battery?
There are two ways to charge the battery.
This method is great for maintenance-free batteries, as there is no need to check how much electrolyte is left. The voltage is set to 13.8-14.5 V. In the first hour, the battery receives 50-60% of the full charge, then the current strength gradually begins to fall.
By the end of the fourth hour, the charge level will reach 90-96%, and the current will drop to 0.2 A. It is almost impossible to fully charge the battery in this way, because no matter how much you charge the battery with such a current, you will not reach 100%.
But even this level of charge is quite enough for the full operation of the car.
How long does this method take? Approximately 4-5 hours. It should be noted that the higher the voltage that is supplied by the charger to the terminals of the car battery, the faster the charge is.
This means that the battery will last longer. But do not set the voltage below 11V. No matter how much you charge your car battery when the voltage is too low, it will only lose charge.
DC charging
For this method, a current equal to 1/10 of the battery volume is set on the charger. It should be noted that the temperature of the electrolyte must be below 35 degrees. That is, if your battery is 60Ah, then you need to charge it with a current of 6A. In the process of charging, the electrolyte boils and begins to release gas.
Important! If during charging the battery has heated up to 50 degrees and above, then it is necessary to stop the process and let it cool down.
How long it takes to fully charge is calculated using a simple formula. The volume of the battery is divided by the current strength and multiplied by the correction factor - 1.2. With a simple calculation, we get a very specific value - 12 hours. If the battery is only slightly discharged, the charging time will be significantly reduced.
Advice! Reduce the current strength by 2-3 times as soon as the electrolyte begins to boil and bring the charge to a lower value. This will increase the time spent, but will reduce the boiling of the electrolytic fluid and thereby extend the life of your battery, which means that your car will not give you unpleasant surprises on the road.
It is also very often possible to find recommendations to charge the battery with a small current. At low current rates, the boiling of the electrolytic liquid is not so active and you can leave the charger overnight. Different sources have different data on how long a car battery can be charged. When fully discharged, it may take several days at low current.
When charging is complete, the battery needs time to release gas. 20-25 minutes will be enough. Check the electrolyte level again and add distilled water if necessary. Close the lids tightly when finished. The battery is now ready to be installed in the car.
If you carefully care for the battery, on time, and most importantly, charge it correctly, it will serve you for many years.
