How to charge a car battery?

During the operation of the engine, the battery (battery), regardless of the type (serviced or unattended), is recharged from the car generator. To control the battery charge on the generator, a device called a relay-regulator is installed. It allows you to supply the battery with such a voltage that is necessary to recharge the battery and is 14.1V. At the same time, a full charge of the battery assumes a voltage of 14.5 V. It is quite obvious that the charge from the generator is able to maintain the battery's performance, but this solution is not able to provide the maximum full charge of the battery. For this reason, it is necessary to charge the battery from time to time using charger (ZU).

*It is also possible to charge the battery using a special starting charger. But such solutions often provide only recharging a dead battery without the ability to fully charge the car battery.

In fact, in the process of charging, there is nothing complicated. To do this, you simply connect the device for charging to the battery itself, and then plug the charger into the network. The process of full charging takes approximately 10-12 hours, if the battery is not completely discharged, the charging time drops.

To find out that the battery is fully charged, you must either look at a special indicator that is on the battery itself, or measure the voltage at the battery terminals, which should be about 16,3-16,4 V.

How to charge a car battery with a charger?

Before you put the battery on charge, you need to perform some more steps. First you need to remove the battery from the car or at least disconnect it from the on-board network by disconnecting the negative wire. Next, clean the terminals of grease and oxide. It is advisable to wipe the surface of the battery with a cloth (dry or moistened with a 10% solution of ammonia or soda ash).

If the battery is serviced, then you additionally need to unscrew the plugs on the banks or open the cap, which will allow the vapors to escape. If there is not enough electrolyte in one of the jars, then add distilled water to it.

Choose a charging method. DC charging is more efficient, but requires supervision, and DC charging only charges the battery 80%. Ideally, the methods are combined using an automatic charger.

DC Charging

• The charging current should not exceed 10% of the rated battery capacity. This means that for a battery with a capacity of 72 Ampere-hour, a current of 7,2 amperes will be required.
• First stage of charging: bring the battery voltage to 14,4 V.
• The second stage: reduce the current by half and continue charging to a voltage of 15V.
• The third stage: again reduce the current by half and charge until the watt and ampere indicators on the charger stop changing.
• The gradual reduction of the current eliminates the risk that the car battery "boils".

DC voltage charging. In this case, you just need to set the voltage in the range of 14,4–14,5 V and wait. Unlike the first method, with which you can fully charge the battery in a few hours (about 10), charging with a constant voltage lasts about a day and allows you to replenish the battery capacity only up to 80%.

How to charge a car battery without a charger at home?

What to do if there is no charger at hand, but there is an outlet nearby? You can assemble the simplest charger from just a few elements.

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.

**Remember, overcharging the battery causes the temperature inside the battery to rise and actively release 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!

Option 1

Details for assembling a simple car battery charger:

1. Incandescent light bulb. An ordinary lamp with a nichrome filament with a power of 60 to 200 watts.
2. semiconductor diode. It is needed to convert the alternating voltage in the household AC mains into direct voltage to recharge our battery. The main thing to pay attention to its size - the larger it is, the more powerful. We do not need much power, but it is desirable that the diode withstand the applied loads with a margin.
3. Wires with terminals and a plug for connecting to a household power outlet.

When carrying out all subsequent ones, be careful, because they are carried out under high voltage and this is life-threatening. Do not forget to turn off the entire circuit from the network before touching its elements with your hands. Carefully insulate all contacts so that there are no bare conductors. ALL elements of the circuit are under high voltage relative to the ground, and if you touch the terminal and at the same moment touch the ground somewhere, you will be shocked.

When setting up the circuit, please note that the incandescent lamp is an indicator of the operation of the circuit - it should burn in the glow floor, since the diode cuts off only one half of the alternating current amplitude. If the light is off, then the circuit is not working. The light may not light if your battery is fully charged, but such cases have not been noticed, since the voltage at the terminals during charging is large, and the current is very small.

All components of the circuit are connected in series.

Incandescent lamp. The power of the light bulb determines what current will flow through the circuit, and hence the current that will charge the battery. You can get a current of 0.17 amps with a 100 watt lamp and take 10 hours to charge the battery for 2 amp hours (at a current of about 0,2 amps). You should not take a light bulb more than 200 watts: a semiconductor diode may burn out from overload or your battery boils.

It is usually recommended to charge the battery with a current equal to 1/10 of the capacity, i.e. 75Ah is charged with a current of 7,5A, or 90Ah with a current of 9 Amperes. The standard charger charges the battery with 1,46 amps, but it fluctuates depending on the degree of battery discharge.

Semiconductor diode polarity and marking. The main thing you need to consider when assembling the circuit is the polarity of the diode (respectively, the connection of the plus and minus terminals on the battery).

A diode only allows electricity to pass in one direction. Conventionally, we can say that the arrow on the marking always looks at the plus, but it is best to find the documentation for your diode, as some manufacturers may deviate from this standard.

You can also check the polarity on the terminals connected to the battery using a multimeter (if the plus and minus are correctly connected to the corresponding terminals, it shows + 99, otherwise it will show -99 Volts).

You can check the voltage at the battery terminals after 30-40 minutes of charging, it should increase by half a volt when it drops to 8 volts (battery discharge). Depending on the charge of the battery, the voltage may increase much more slowly, but you should still notice some changes.

Don't forget to unplug the charger from the outlet, otherwise after 10 hours, it may overcharge, boil and even deteriorate.

Option 2

A battery charger can be made from a power supply from a third-party device, such as a laptop. Please note that these actions represent a certain danger and are performed solely at your own peril and risk.

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.

How to quickly charge a car battery?

But what if you need to quickly charge a dead car battery and there are no 12 hours for a normal procedure? For example, if the battery is dead, but you need to go. Obviously, in such a situation, emergency recharging will help, after which the battery will be able to start the car engine, the rest will be completed by the generator.

To recharge quickly, the battery is not removed from its regular place. Only the terminals are disconnected. The procedure is as follows:

1. Switch off the car ignition.
2. Remove terminals
3. Connect the charger wires in this way: "plus" to the "plus" of the battery, "minus" to the "mass".
4. Connect the charger to 220 V.
5. Set the maximum current value.

After 20 (maximum 30) minutes, disconnect the device for charging. This time at maximum power should be enough to charge the battery to start the car engine. It is best to use this method only in cases where normal charging is not possible.