Many users are familiar with branded batteries ("Duracell Turbo", in particular) with a charge control function using the "POWERCHECK" technology. By the color of the strip applied to them, which appears when you press on a certain place, one can judge the degree of its discharge. Anyone who would like to take advantage of these opportunities will need to understand how this function is implemented and how it affects the state of the battery.
Operating principle
At its core, the battery discharge indication technology is very simple. It consists in the fact that two layers of polymer material are applied to the element, in which a film-type resistor of variable width is integrated. The first layer is made in the form of several multi-colored stripes with a color transition from red to light green. The other is a temperature-dependent paint that becomes transparent when heated.
To reduce the heat capacity of such a formation, a thin layer of paper is placed between the battery case and the polymer film.
The resulting simple construction works as follows:
- when you press the marked spots, the polymer film is deformed and connects the plus and minus power supply to the integrated resistor;
- due to this, a closed circuit is formed with an electric current flowing through it;
- since the film is uneven in thickness, then it heats up in different ways.
In places with a minimum standard size, heating is faster and vice versa.
Discharge rate
Due to the considered property of the two-layer coating, the following occurs when checking the battery. As soon as the person controlling it presses his fingers on the selected areas, the thermal paint in these places becomes transparent and the user distinguishes the red color (if the battery is discharged). In a situation where its charge is close to full, the strength of the current flowing in the circuit is enough to warm up the paint layer and fully develop the colored strip (from red to light green).
At a low current, the strip does not warm up very much in the widest place, as a result of which the thermal layer of the paint is only partially discolored. This indicates that the battery is slightly discharged (part of the light green spectrum is not visible in this case). If, with the next press, it is not possible to distinguish even the red section of the strip, this means that the element is completely discharged.
Note: If desired, the considered method of checking the state of charge can be applied to any battery.
The main difficulty that arises during its implementation is that you first need to remove the protective film from the element in order to stick the strip and measure the residual charge.
It should also be taken into account that with frequent checks of the state of charge of the batteries, they gradually "sit down" due to the control discharge currents. In this case, you will have to come to terms with the additional costs of purchasing new items.