Comparison ISTA Standard A1 6CT-77R vs Varta Silver Dynamic 577400078

— Maintainable. Only classic lead-acid batteries (see "Type") can be serviced: they are easy to distinguish even externally — by the presence of removable plugs that provide access to internal containers with electrolyte. The latter is a mixture of sulfuric acid with water, and with each charge, some of this water "boils away" (decomposes into oxygen and hydrogen and evaporates). This happens especially intensively during overcharging or charging at high voltage. Battery maintenance consists of periodically replenishing the water reserves in the electrolyte — without this, a decrease in its level leads to damage to the plates due to contact with air, which irreparably worsens the battery's characteristics. On average, maintenance should be carried out 1-2 times a year (15-20 thousand km of mileage for a passenger car) and these periods usually coincide with the terms of scheduled maintenance. However, this value may vary depending on the characteristics of both the battery itself and its operation; More detailed information is usually contained in the instructions for specific models. "Refilling" should be done exclusively with distilled water, since even a relatively small amount of foreign impurities can damage the plates.

— Maintenance free. As the name suggests, such batteries do not require the maintenance described above; this is achieved in a number of ways, in particular by filling the elect...rolyte with a reserve for the entire service life or using gel (see "Type"). With obvious advantages due to ease of use, maintenance-free batteries at the same time have one drawback: they are much more sensitive to deep discharge (capacity decreases), and, accordingly, tolerate cold and long periods of downtime worse.

The starting power of the battery, measured according to the EN standard (the unified standard of the European Union). According to this standard, the starting power is the maximum power that the battery can deliver for 30 seconds at an electrolyte temperature of -18 °C without the voltage dropping below a certain level (for standard 12 V batteries - not lower than 7.2 V). The term "starting" appeared because this operating mode is similar to starting an engine, when the battery has to deliver a high-power power to the starter for a short time.

The recommended starting power value is generally related to the weight category of the vehicle: the heavier it is, the more powerful the power usually needed to start it. And many manufacturers directly indicate the recommended values in the characteristics of a particular vehicle model. If the battery is purchased as a replacement, the general rule is: its starting power should be no less than that of its predecessor.

Note that in practice, starting power designations may be encountered according to 3 more standards: SAE (USA), DIN (Germany) and TU (GOST 959-91). The first is almost identical to EN, and DIN and TU are quite easy to translate into EN and vice versa: they are similar to each other, and each of them gives a number approximately 1.7 times smaller than NE. That is, for example, to replace a 200 A battery according to TU, you should look for a model with a power of at least 340 A (200 * 1.7) according to EN.