Controllers themselves are useful devices. And in order to better understand this topic, it is necessary to work with a specific example. Therefore, we will consider the battery charge controller. What does he represent? How is it arranged? What are the job features?
What does a battery charge controller do
It serves to monitor the recovery of energy losses and spending. First, he is engaged in monitoring the conversion of electrical energy into chemical energy, so that later, if necessary, there is a supply of the required circuits or devices. It is not difficult to make a battery charge controller with your own hands. But it can also be removed from power supplies that have failed.
How the controller works
Of course, there is no universal scheme. But many in their work use two trim resistors that regulate the upper and lower voltage limits. When it goes out of bounds,then the interaction with the relay windings begins, and it turns on. While it is working, the voltage will not fall below a certain, technically predetermined level. Here we should talk about the fact that there is a different range of boundaries. So, for the battery, three, and five, and twelve, and fifteen volts can be installed. Theoretically, everything rests on the hardware implementation. Let's look at how the battery charge controller works in different cases.
What types are there
It should be noted that there is a significant variety that battery charge controllers can boast. If we talk about their types, let's make a classification depending on the scope:
- For renewable energy.
- For household appliances.
- For mobile devices.
Of course, the species themselves are much larger. But since we are considering the battery charge controller from a general point of view, they will suffice for us. If we talk about those that are used for solar panels and windmills, then in them the upper voltage limit is usually 15 volts, while the lower one is 12 V. In this case, the battery can generate 12 V in the standard mode. The energy source is connected to it using normally closed relay contacts. What happens when the battery voltage exceeds the set 15V? In such cases, the controller closes the relay contacts. As a result, the power source from the battery is switched to the load ballast. It should be noted that it is not particularly popular with solar panels due to certain side effects. But for wind generators, they are mandatory. Home appliances and mobile devices have their own characteristics. Moreover, the battery charge controller of the tablet, touch and push-button cell phones are almost identical.
Looking inside a cell phone's lithium-ion battery
If you open any battery, you will notice that a small printed circuit board is soldered to the terminals of the cell. It's called a protection scheme. The fact is that lithium-ion batteries require constant monitoring. A typical controller circuit is a miniature board on which a circuit made of SMD components is based. It, in turn, is divided into two microcircuits - one of them is the control one, and the other is the executive one. Let's talk in more detail about the second one.
Executive scheme
It is based on MOSFET transistors. Usually there are two. The microcircuit itself can have 6 or 8 pins. For separate control of the charge and discharge of the battery cell, two field-effect transistors are used, which are located in the same housing. So, one of them can connect or disconnect the load. The second transistor does the same actions, but with a power source (which is the charger). Thanks to this implementation scheme, you can easily influence the operation of the battery. You can use it elsewhere if you wish. ButIt should be borne in mind that the battery charge controller circuit and it itself can only be applied to devices and elements that have a limited range of operation. We will talk about such features in more detail now.
Overcharge protection
The fact is that if the voltage of a lithium battery exceeds 4, 2, overheating and even an explosion may occur. For this, such elements of microcircuits are selected that will stop charging when this indicator is reached. And usually, until the voltage reaches 4-4.1V due to use or self-discharge, no further charging will be possible. This is an important function assigned to the lithium battery charge controller.
Overdischarge protection
When the voltage reaches critically low values that make the operation of the device problematic (usually in the range of 2, 3-2, 5V), then the corresponding MOSFET transistor is turned off, which is responsible for supplying current to the mobile phone. Next, there is a transition to sleep mode with minimal consumption. And there is a rather interesting aspect of the work. So, until the voltage of the battery cell becomes more than 2.9-3.1 V, the mobile device cannot be turned on to work in normal mode. Probably, you might have noticed that when you connect the phone, it shows that it is charging, but does not want to turn on and function in normal mode.
Defense mechanisms
It should be noted that the battery charge controller hasa number of elements that should protect against negative consequences. So, these are parasitic diodes that are placed in field-effect transistors, a charge detection circuit and a few other small additions. Oh, yes, and if it is possible to check the battery charge controller and find out the performance of the energy source, then its functioning can be restored even with “death”. Of course, this means simply stopping work, and not an explosion or meltdown. In this case, special devices that conduct a special “recovery” charge can help. Of course, they will work for a long time - the process can stretch for tens of hours, but after successful completion, the battery will work almost like new.
Conclusion
As you can see, the Li-Ion battery charge controller plays an important role in ensuring the longevity of mobile devices and has a positive effect on their service life. Due to the ease of production, they can be found in almost any phone or tablet. If you want to see with your own eyes, and touch the Li-Ion battery charge controller and its contents with your hands, then when disassembling, you should remember that you are working with a chemical element, so you should be careful.
