What and why?
First of all, do not hope that once a fully charged battery is put in storage, it will remain so. Alas, such a phenomenon as self-discharge has not been canceled. And this process is highly dependent on temperature. In the hot summer, the car battery "sits" in a few months. This is under the bed. A couple of weeks of downtime can be enough in a car: the fact is that modern on-board electronics never turn off completely: the clock goes on, the radio stations recorded in the radio's memory are saved, the engine controller is also just asleep, not to mention the alarm, which is constantly on the alert.
As a result, a hundred or two milliamps of discharge current may well run. Ten hours - and a couple of ampere hours as it never happened. Week - and only half the capacity is left. And by the way, if you discharge the battery to 40%, then it may not scroll the starter! But okay, just that. The trouble is that in a discharged lead-acid battery there is a very harmful process - sulfation. Lead sulfate formed on the plates for the battery is a real poison. And such a battery generally ceases to take charge!
In general, we bought a car - buy a charger, it will not be superfluous. Even if you drive regularly, in winter, with frequent cold starts and short throws from home to work, the battery does not have time to warm up, and when it is cold, it categorically does not accept the charge. As a result, every day the energy supply in it decreases, despite a perfectly working generator. The standard warning light does not light up, and the battery is empty. Note that this is an occasion to purchase one of the Comfort Indicator accessories by the Swedish company CTEK Sweden AB. With it, at first glance you will see the real state of the battery. The green LED - everything is in order, yellow - it is time to think, red - it is urgent to charge. But with what?
With computer and button
Are you at odds with a personal computer? And all the same, the microprocessor that CTEK Sweden AB packaged in a small plastic box of the CTEK MXS 5.0 charger is controlled without a keyboard and mouse - the only button. Truly: made in Sweden - made wisely! But why goat button accordion, excuse me, charging rectifier - a computer? It turns out that this is a very useful thing, if not just stupidly driving electricity into the battery, but organizing this process so that the battery not only does not deteriorate, but also corrects, possibly, lost health.
So, pressing that single button starts a process consisting of eight (!) Stages. It all starts with desulfation, when voltage pulses help to remove sulfates from the surface of the plates and thereby return the battery to its original declared capacity. In the second stage, the ability of the battery to take charge is tested. And, if everything is in order, the third stage begins - the charge with the maximum current (it is limited to 5 A) until approximately 80% of the capacity is reached. Stage 4 (“Absorption”) brings the charge to 100% with a gradually decreasing current. And finally, at the fifth stage, diagnostics is carried out for the ability of the battery to hold the received supply of electricity. Actually, this could be finished by unhooking crocodiles as soon as the corresponding indicator lights up.