Used 3 years. During this time, most of the time I simply and successfully charged the car battery. But it is worth noting some features of the memory. As a rule, a motorist uses a charger on an already running battery with partial sulfation of the plates. If you set the charge voltage and current as stated in the instructions, then the charger will display a charge completion message a little earlier than it actually is (in fact, as soon as the current drops and the charge is over message appears, the charge of the current capacity will be completed). Desulfation requires additional equipment and techniques, although the manufacturer could implement this in this device.