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Simple universal automatic charger

I tried to put in the title of this article all the advantages of this scheme, which we will consider and of course I did not quite get it. So let's now consider all the advantages in order. The main advantage of the charger is that it is fully automatic. The circuit monitors and stabilizes the desired battery charging current, controls the battery voltage and how it reaches the desired level - reduces the current to zero.

Which batteries can be charged?

Virtually everything: lithium-ion , nickel-cadmium, lead and others. The scope of application is limited only by the charge current and voltage. For all household needs this will be enough. For example, if you have broken the built-in charge controller, then you can replace it with this circuit.Cordless screwdrivers, vacuum cleaners, flashlights and other devices can be charged with this automatic charger, even car and motorcycle batteries.

Where else can you apply the circuit?

In addition to the charger you can apply this circuit as a controller charging for alternative energy sources, such as solar panels. Also, the circuit can be used as an adjustable power supply for laboratory purposes with short circuit protection.

Main advantages:

  • - Simplicity: scheme contains Only 4 fairly common components.
  • - Complete autonomy: control of current and voltage.
  • - The LM317 chips have built-in protection against short circuits and overheating.
  • - Small dimensions of the end device.
  • - Large operating voltage range 1.2-37 V.
Disadvantages:
  • - Charging current up to 1.5 A. This is most likely not a disadvantage, but a characteristic, but I will define this parameter here.
  • - At a current greater than 0.5 A, it requires installation on a radiator. Also consider the difference between input and output voltage. Than this difference will be biggerthe more the microcircuits get warm.

Automatic charger circuit

Simple universal automatic charger
The diagram does not show the power source, but only the adjustment unit. The power source can be a transformer with a rectifier bridge, a power supply from a laptop (19 V), a power supply from the phone (5 V). It all depends on what goals you are pursuing. The scheme can be divided into two parts, each of which functions separately. The first LM317 assembled current stabilizer. The stabilization resistor is simply calculated: “1.25 / 1 = 1.25 Ohm”, where 1.25 is a constant that is always the same for all and “1” is the stabilization current you need. Calculate, then choose the closest resistor from the line. The higher the current, the more power the resistor needs to be taken. For a current from 1 A - a minimum of 5 watts. The second half is a voltage regulator. Here everything is simple, with a variable resistor you put the voltage of the charged battery. For example, in automotive batteries it is somewhere equal to 14.2-14.4. To configure, we connect a 1 kΩ load resistor to the input and measure the voltage with a multimeter. Expose the subsistor to the desired voltage and all.As soon as the battery is charged and the voltage reaches the set value, the microcircuit reduces the current to zero and the charging stops. I personally used such a device to charge lithium-ion batteries. It's no secret that they need to be charged correctly and if they make a mistake, they can even explode. This memory handles all tasks.
Simple universal automatic charger
Simple Universal Automatic Battery Charger
To monitor the presence of a charge, you can use the circuit described in this article - Current Indicator. There is also a circuit for enabling this chip in one: and stabilizing the current and voltage. But in this version there is not quite linear work, but in some cases it may be useful. An informative video, not only in Russian, but the calculation formulas can be understood.
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