You cannot directly connect the laptop power supply to the battery terminals. The output voltage is about 19 V, and the current is about 6 A. The current is enough to charge a 60 A/h battery, but what about the voltage? There are options here.

A charger from a laptop power supply can be implemented in two completely different ways.+

• No modification of the power supply. It is necessary to connect a powerful light bulb from the headlight in series with the car battery. In this case, such a light bulb will serve as a current limiter. The solution is very simple and affordable.
• With modification of the power supply. Here it is necessary to reduce the voltage of the laptop power supply for normal charging to 14 - 14.5 V.

We'll take a more interesting route and briefly tell you how easy it is to lower the voltage of a laptop's power supply. The experimental block will be universal charger to a laptop called Great Wall.

First of all, we disassemble the case, try not to fray it too much, we still have to use it.

As you can see, the unit produces a voltage of 19 V.

The board is built on TEA1751+TEA1761.

To better understand the matter, one of the Chinese sites had a diagram of a very similar block.

The only difference is in the ratings of some parts.

To reduce the output voltage, we are looking for a resistor that connects the sixth leg of the TEA1761 and the plus from the output of the power supply (marked in red in the photo).

In the diagram, this resistor consists of two (they are also circled in red).

For convenience, we present the purpose and location of the legs from the TEA1761 datasheet.

We unsolder this resistor and measure its resistance - 18 kOhm.

We take out a 22 kOhm variable or tuning resistor from the bins and set it to 18 kOhm. We solder it in place of the previous one.

Gradually reducing the resistance we achieve a reading of 14 - 14.5 V at the output of the power supply.

Having received required voltage you can unsolder it from the board and measure the current resistance - it was 12.37 kOhm.

After all, you need to select a constant resistor with a value as close to this value as possible. For us it will be a pair of 10 kOhm and 2.6 kOhm. Alas, nothing like this was found in the SMD version; the ends of the resistors had to be placed in a thermal casing.

We solder these resistors.

We test the operation of the unit - 14.25 V at the output. The voltage for charging a car battery is just right.

We assemble the power supply and connect the crocodiles at the end of the cord. (It is necessary to carefully check the polarity at the output of the cord; in some power supplies, “-” is the center wire, and “+” is the braid).

The charger from the laptop power supply works as expected, the current in the middle of the charging process is about 2-3 A. When the charging current drops to 0.5-0.2 A, the charging process can be considered complete.

For convenience, the charger can be equipped with an ammeter screwed to the case, or a control LED, which will signal the end of the charge. As an additional precaution, it is advisable to use at least some kind of protection against polarity reversals.

Charger protection circuit

Let's take a closer look at the polarity reversal protection circuit on a field-effect transistor. The voltage loss on the field-effect transistor is minimal, and the response time is no more than 1 μsec. +

The scheme works like this. At correct connection The field effect transistor is open, and all the current flows to the output of the circuit. At short circuit, overload, or polarity reversal, the voltage drop on the shunt and field-effect transistor is enough to trigger a low-power bipolar transistor. When the transistor fires, it closes the gate field effect transistor to the ground, covering it completely.

Based on materials from the INTERNET.

Ways to charge a car battery without a charger

Any car owner is familiar with the situation of a dead battery. I need to drive, but the car won’t start. Everyone knows that you need to charge the battery and the problem will be solved. But what to do if this is not possible? That is, Charger(memory) is missing. This can happen for various reasons. The charger could have broken down, been left in a garage far from you, or simply not been there. What to do in this case? How to charge a car battery without a charger? In this article we will look at several examples of charging a battery without a charger.

Here we should reason as follows. What do we need to charge? A car battery with a nominal voltage of 12 volts and an average capacity of 50-70 Ah. This means that you need a power supply with an output voltage of more than 14 volts, which produces a current of at least 1 ampere. Although 1 ampere is not enough to charge the average car battery. It is better if the power supply provides 3-4 amperes.

Some ballast will also be required. This could be a light bulb or a resistor that will be included in the circuit when charging the battery. Do not neglect the ballast load, since without it the power supply or car battery may fail.

And of course you will need controls electrical parameters when charging. These are an ammeter and a voltmeter. It is easier and more convenient to use a multimeter, which has voltmeter and ammeter modes, as well as much more.

In addition to the above, you will need copper wires, soldering iron with solder (if you are making a homemade charger for permanent use), insulating tape.

Now let's look at several options for how to charge a car battery without a charger.

Ways to charge a car battery without a charger

Before we begin, I would like to say a few words about safety. If you do not have experience with electricity, then it is better not to engage in the actions described below at all (with the exception of the option with portable batteries). It is better to purchase a battery charger from a car store and charge it in a civilized way. If your experience in handling cars is not enough for this, then it is better to contact a battery service station.

When performing work, observe all safety precautions required when working with electricity. When charging a battery with a homemade charger, there is one significant problem. There is no control over the end of charging. In most factory chargers, the process stops automatically, but in the case of a homemade charger, you will have to monitor this yourself.

When the battery is recharged, the process of active release of hydrogen and oxygen on the electrodes begins. Together they form an explosive mixture that can explode very violently when struck by a spark. Therefore, you need to charge the battery in a well-ventilated area, with no open flames or sparks nearby.

Charge the battery using a portable charger

Nowadays there are enough such portable batteries on sale. Most of them can be classified as starting-charging. That is, with their help you can start the car engine, as well as simply recharge the battery. More often they are used as starting devices somewhere in the field.

Portable chargers are made on the basis of lithium batteries. Some advanced models even install small containers. Often such devices have “crocodiles” for connecting to the terminals and also an adapter for the cigarette lighter. It is better to take exactly such models so that recharging of the car battery through the cigarette lighter is available. The battery of such devices can be charged from the mains via an adapter or from on-board network car when the engine is running.

Based on functionality, such chargers can be divided into three groups:

• Household;
• Professional;
• Combined.

The design of portable starting and charging devices usually includes a diode bridge, a transformer (rectifier) ​​and an ammeter. More expensive devices have different kinds protection, as well as the ability to adjust current and voltage. Professional models have more power than others (40-50 watts). In addition, they have the ability to charge several car batteries at once.

enjoy portable charger Even an inexperienced car owner can do it. Simply connect the device terminals to the outputs car battery observing the polarity and wait a while. Let’s say right away that it will not be possible to fully charge the battery from a portable charger. Most likely, you won’t be able to charge even 50% (this depends on the capacity). But you can give the battery the charge necessary to start the engine. After this, the battery will be recharged from the generator.

Using a laptop charger

Now let’s talk about how to charge a car battery without a charger using a laptop charger. To do this, you will need a laptop charger, a light bulb or resistor, and copper wires. The image below schematically shows a homemade charger using laptop charging.

To assemble the circuit, you need to bring out two wires from the laptop charging, plus and minus. The plus is inside, the minus is outside. After this, connect the negative wire to the negative terminal of the battery. And then connect a car light bulb or trimming resistor into the gap. The option with a resistor is preferable, since the resistance value can be changed. Connect the second terminal of the resistor to the positive terminal of the car battery. Below is how the whole circuit looks in reality.

The circuit shows a resistance of 10 ohms just for example, based on a current of 2 amperes. If you want to charge the battery faster, reduce the resistance. This is why a tuning resistor is convenient.

This way you can fully charge your car battery. You just need to control the end of the process. To do this, you can measure the voltage at the terminals. If it is above 14 volts and does not change, and the electrolyte is actively “boiling,” then the process can be stopped. This, of course, is all approximate, but in such conditions it will be suitable.

Many modern chargers for car batteries, incl. Generator voltage regulators installed on cars operate according to the following algorithm:

First, the battery is charged with maximum current, the voltage on the battery increases to a value of 14.4 V (2.4 V per cell), then the battery is charged constant voltage 14.4 V (at the same time, the charging current gradually decreases and is close to 0 at 100% charge)

This mode is optimal for acid and gel batteries. Its advantages are:

• fast battery charge up to 70 - 80% of battery capacity
• overcharging of the battery is eliminated (the battery can be connected to the charger indefinitely)

Charger for batteries from laptop ACER ADP 90 SB BB

This power supply is almost ideal for use as a charger.

Its output parameters:
• Output voltage: 19 V;
• Maximum output current: 4.74 A.

This power supply supports output voltage 19 V, and in case of overload, the voltage at its output is reduced so much that the output current does not exceed 4.74 A.

Everything you need in this device- change the stabilization voltage. In order for the output voltage of the power supply to become equal to 14.4 V, it is necessary to reduce the resistance R133. You can replace R133 with a value of 25.5 kOhm with a resistor of 18.42 kOhm or solder a resistor of 68 kOhm in parallel with the existing R133 25.5 kOhm. In the second case, the output voltage will be about 14.5 V

Remove capacitor C136. Otherwise, when the output current exceeds 4.74 A, the power supply is repeatedly restarted, the circuit operates in protection mode, but it should be in current limiting mode.

The power supply can be used in two modes:
• Power supply 19 V 4.74 A;
• Charger for 14.4 V 4.74 A batteries.

To do this, it is enough to provide a mode switch with which you can select the value of R133.

Replacing diode assembly D131 on the green and red LEDs you can control (current stabilization / voltage stabilization) the operating mode of the charger.

Resistor R105 acts as a shunt across which the voltage drop is measured. When starting up for the first time, you should pay attention to the heating of this element.

PS: check this diagram in practice, I failed due to the lack of this power supply. Therefore, I draw your attention to the possible heating of resistor R105.

Diagram for checking voltage regulators:
MOTOROLA 9RC2054
MOBILETRON VR-VW010
TRANSPO M511
HUCO 13 0696
GER04

The VALEO SG15L027 155A generator is installed on RENAULT SCENIC 2 cars with a 1.9 dci 120 hp engine. F9Q.

A water-cooled generator is used to heat the windshield using heating elements

How to charge a car battery using a laptop power supply.
Power supply parameters Uout 18.5 V Iout 3.5 A
I found a 12 V 55 W low beam lamp to limit the charging current.
Connected in series:
+ power supply output
+ lamps
- lamps

Many modern chargers for car batteries operate according to the following algorithm:

• Battery charge DC, the battery voltage increases to 14.4 V (2.4 V per cell)
• Charging the battery with a constant voltage of 14.4 V (in this case, the charging current gradually decreases and is close to 0 at 100% charge)

Many people purchasing a new computer equipment, throw their old one in the trash system unit. It's pretty short-sighted, because it may still contain functional components, which can be used for other purposes. In particular, we are talking about the computer power supply, from which you can.

It is worth noting that the cost of making it yourself is minimal, which allows you to significantly save your money.

The computer power supply is a voltage converter, respectively +5, +12, -12, -5 V. Through certain manipulations, you can make a completely working charger for your car from such a power supply with your own hands. In general, there are two types of chargers:

Chargers with many options (engine starting, training, recharging, etc.).

A device for recharging the battery - such charges are needed for cars that have low mileage between runs.

We are interested in the second type of chargers, because most vehicles are used for short distances, i.e. the car was started, driven a certain distance, and then turned off. Such exploitation leads to the fact that battery The car runs out of charge quite quickly, which is especially typical in winter. Therefore, such stationary units are in demand, with the help of which you can very quickly charge the battery, returning it to working condition. The charging itself is carried out using a current of about 5 Amps, and the voltage at the terminals ranges from 14 to 14.3 V. The charging power, which is calculated by multiplying the voltage and current values, can be provided from the computer power supply, because its average power is about 300 -350 W.

Converting a computer power supply into a charger