The controllers themselves are useful devices. And in order to better understand this topic, you need to work with a specific example. Therefore, we will consider the battery charge controller. What is he like? How is it arranged? What features of work exist?
What the battery charge controller does
It serves to monitor the recovery of energy losses and expenditures. First, he is involved in monitoring the conversion of electrical energy into chemical energy, so that, if necessary, he could supply the required circuits or devices. Making a battery charge controller yourself is not difficult. But it can also be extracted from power sources that are out of order.
How the controller works
Of course, a universal scheme does not exist. But many in their work use two post-construction resistors that regulate the upper and lower voltage limits. When it goes beyond the specified limits, then interaction with the relay windings begins, and it turns on. As long as it works, 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 depends on the hardware implementation. Let's look at how the battery charge controller works in different cases.
What are the types
It should be noted the significant variety that the battery charge controllers can boast of. If we talk about their types, let's make a classification depending on the scope:
- For renewable energy sources.
- For household appliances.
- For mobile devices.
Of course, the species themselves are much larger. But since we consider the battery charge controller from a general point of view, then we have enough of them. If we talk about those that are used for solar panels and windmills, then the upper voltage limit is usually 15 volts, while the lower one is 12 V. Moreover, the battery can generate 12 V in the standard mode. The power source is connected to it using normal closed relay contacts. What happens when the battery voltage exceeds the set 15 V? In such cases, the controller closes the relay contacts. As a result, the power source from the battery switches to load ballast. It should be noted that they are not particularly fond of installing it for solar panels because of certain side effects. But for wind generators, they are mandatory. Household appliances and mobile devices have their own characteristics. Moreover, the controller of the battery charge of the tablet, touch and push-button cell phones are almost identical.
Take a look at the lithium-ion cell phone battery
If you pick up any battery, you will notice that a small
printed circuit board is soldered to the cell's terminals
. It is called a protection circuit. The fact is that
lithium-ion batteries require constant monitoring. A typical controller circuit is a miniature circuit 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, and the other is the executive. Let's talk in more detail about the second.
Executive scheme
It is based on MOSFET transistors. Usually there are two. The chip 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 one housing. So, one of them can connect or disconnect the load. The second transistor does the same, but with a power source (which is the charger). Thanks to this implementation scheme, it is possible to influence the battery operation without problems. If desired, it can be used elsewhere. But it should be borne in mind that the circuit of the battery charge controller and it can only be applied to devices and elements, which have a limited range of operation. We’ll talk about these features in more detail now.
Overcharge protection
The fact is that if the voltage of the
lithium battery exceeds 4.2, then overheating and even an explosion can occur. For this, such elements of microcircuits are selected that will stop charging when this indicator is achieved. And usually, until the voltage reaches a value of 4-4.1 V due to use or in the process of self-discharge, further charging will be impossible. This is an important function that is assigned to the lithium battery charge controller.
Over discharge protection
When the voltage reaches critical values that make the functioning of the device problematic (usually this is a range of 2.3-2.5V), 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 here 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. 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.
Protective gear
It should be noted that the battery charge controller has a number of elements that should protect against negative consequences. So, these are parasitic diodes that are located in field-effect transistors, a charge detection circuit, and a few other small additions. Ah, yes, and if it is possible to check the battery charge controller and find out the operability of the energy source, then its functioning can be restored even in the event of “death”. Of course, this simply means shutting down, not blasting or melting. In this case, special devices that conduct special “recovery” charging 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 long-term working life of mobile devices and positively affects their service life. Due to the simplicity of production, they can be found on almost any phone or tablet. If there is a desire to see with your own eyes, and touch the Li-Ion battery charge controller and its contents with your own hands, then when analyzing, you should remember that the work is carried out with a chemical element, so you should be careful.