For example, frequent high-current charging significantly reduces battery life. Therefore, usually the maximum charge current is limited to a value numerically equal to 1/10 of the capacity, expressed in ampere-hours. It would seem that the fastest is to drive these 6 amperes for 10 hours, and now the battery is fully charged. But not so simple: at the end of such charging, vigorous gas evolution begins, and it is not only dangerous in itself (hydrogen forms an explosive mixture with air), but also leads to a decrease in the electrolyte level and a change in its density.
All this is not at all useful for a battery. Therefore, the charging method with constant voltage is more often used. Then, at the beginning of the process, the current can reach many tens of amperes (this is what happens in the car), but then it quickly decreases and finally drops to zero when the voltage of the charger and battery are equalized. In this way, however, the battery cannot be fully charged at 100%, and the process is very lengthy.
And it would also be nice to combine the useful with the pleasant and arrange the battery for prevention, eliminating the onset of sulfation and stratification of the electrolyte. But for this we need special modes and knowledge that the average car owner does not possess. Fortunately, this knowledge is owned by specialists from the Swedish company STEK SWEDEN AB, who since 1997 have only been engaged in the corresponding research and development of chargers. And today, thanks to the widespread introduction of electronics and microprocessors, all the worries about the correct choice of charging mode can be assigned to electronic brains with a wired special program, which is the company's know-how. The owner will only have to connect the terminals to the poles (if he makes a mistake, it’s okay!) And press only one button.
This initiates a complex process, starting with the elimination of possible sulfation by a pulsating current. Then, fast recharging will begin with a fixed current value, which will switch to constant voltage charge mode. A separate step will eliminate electrolyte separation. Interestingly, STEK chargers cannot recharge the battery in principle: they can be left connected to it at least for the whole time, and then the battery will always be in full combat readiness. There is a separate mode for winter (when high voltage is needed) and a mode for powering the on-board electronics during car maintenance, when the battery is removed. This ensures a trouble-free update of the controller firmware, data storage in the radio and learning microprocessors (there are more of them in modern cars).
Now let's look at the assortment of STEK chargers offered. Among them, the professional series consisting of devices MXS 10, MXS 25, MXT 4.0, MXT 14 and MXTS 70 stands out. The first two are designed for batteries with capacities from 40 to 200 and 500 Ah, respectively. The number in this case indicates the maximum charging current. MXT chargers are used to charge 24 V batteries with a capacity of 8–100 Ah and 28–300 Ah, respectively, and again the figure indicates the maximum current. Finally, the last product in the line is a true station wagon for car services. It provides a charge of both twelve and twenty-four-volt batteries with a capacity of up to 1500 Ah at a current of up to 70 A.
There is a rather exotic charger D250S Dual. Its peculiarity is work not from an AC network, but from a constant voltage, which various sources can give out. For example, a car generator, windmills, solar panels, etc. His "dualism" is manifested in the automatic selection of the most suitable "generator" at the moment. For motorists who also would like to maintain the health of the battery for many years, another line of chargers is proposed, which differs fundamentally from professional ones, perhaps only in the range of battery capacities and maximum charging current.
Two of them XC 0.8 and XS 0.8 are addressed to motorcyclists and are designed for batteries with a voltage of 6 and 12 V, respectively. The capacity of motorcycle batteries is usually small and a charging current of 0.8 A is enough for them. MXS 3.6 and MXS 5.0 are all-rounders. Their charging current can be not only 3.6 or 5 A, but also 0.8 A. The developers thought of those motorists who have a two-wheeled friend. The most powerful in the MXS 7.0 line is more suitable for owners of heavy pickups, boats or caravans on wheels. All chargers provide at least four modes during the charging process, and the last two of these are all eight!
Those who were interested in STEC chargers before may be surprised at the new names. And where did the MULTI series chargers go (MULTI XS 3600, MULTI XS 4003, MULTI XS 7000)? The fact is that now the transition from them to the new generation of chargers described in the article is just happening. All devices of the new line, in which, note, completely new models, for example, CTEK MXS 10, are equipped with a more powerful microprocessor, providing even more reliable battery charge, and some of them have added more informative indication of the entire charging process. The design of the chargers has also undergone minor changes and the appearance of the package has radically changed. From the point of view of ensuring battery power and the reliability of the MULTI device is no worse than the models that come to replace them.