See also Section Battery check, care and charging.
The installed 12V battery consists of six jars containing positive and negative plates, which are dipped in a sulfuric acid solution. The task of the battery is to generate current for starting the car, ignition and for lighting, as well as for other consumers of electricity.
The battery is 100% efficient at 27°C. At -18°C, the efficiency drops to 40%. Now, in order to start the engine, it is necessary to have more than twice as much energy as was needed at 27°C.
starting power (starting current) indicates the battery's ability to start the vehicle in very cold weather. It shows the current in amps that the battery delivers for 30 seconds at -18°C without a voltage drop below 7.2 volts (the minimum level required for a reliable start). The higher this figure, the greater the starting power of the battery.
Standby power indicates the time in minutes during which the battery delivers a current of 25 amps at 27°C., i.e. the amount of time the battery provides for the operation of all auxiliary devices in the car at night and in bad weather with a faulty alternator.
In winter conditions at -18°C and below, the battery will be poorly charged due to an increase in internal resistance. During short trips in winter, the energy expended by the battery for starting is not restored. As a result, the battery wears out, constantly discharges and eventually fails.
During the summer months, after long trips, the engine becomes very hot and it often happens that it is difficult to start it again. Such «hot starts» sometimes require as much power as in cold weather, or more. This is especially true for high-compression, large-displacement engines and air-conditioned vehicles. This once again emphasizes the importance of choosing the right battery according to the vehicle's engine.
Purchasing a new battery
Probably the most important thing a buyer should pay attention to is the characteristics of the battery. There are three of them. The first is the nominal voltage, it is the same for all batteries, and it is impossible to make a mistake. When buying, it is advisable to check the battery with a load plug. The second is the capacitance, measured in ampere / hours (A/h), means, roughly speaking, the amount of electricity stored in the battery. It depends on the capacity how long you can turn the engine with the starter, more precisely, how many attempts to start the engine can be made. The price of a battery is almost directly proportional to its capacity. And the third characteristic is the starting current (measured in amperes. A), i.e. current supplied to the starter during cranking. On batteries, it can be indicated according to four different systems: GOST (on domestic), EN (European standard), SAE (american standard) and DIN. The last, German standard, is closest to our GOST and is set on most European «default», i.e. when the standard system is not specified. The larger it is, the faster and with more force the starter will turn the engine.
It is better if you buy a battery with the characteristics that are indicated in the operating instructions for your car: this way it will last you longer at minimal cost. You can save money and buy a battery with a smaller capacity, but it will serve you less than usual and will not cope well with winter starting. By purchasing a battery of even slightly larger capacity, you will not win in terms of service life, because. Constant undercharging of the battery will lead to sulfation of the plates, and you will lose money. You should also not get carried away with increased starting current: you will burn the starter. It is better to change the oil in the engine, and there will be no problems with starting.
Recently, the country's market is full of low-quality goods and fakes. Batteries are no exception. There are several signs by which it is possible to distinguish the original from the fake with sufficient accuracy. First and, perhaps, most importantly, the country of manufacture and the producing plant must be indicated on the battery, it is better if with an address. Secondly, the date of manufacture must be indicated, which is very important if the battery is flooded. Each battery must be accompanied by a technical data sheet, but the presence of instructions is optional. This is due to the fact that in the West, batteries are almost never sold at retail, they are installed by specialists at service stations. Thirdly, a high-quality battery is unthinkable without a high-quality case, good plugs and smooth output terminals, often lubricated with technical protective grease against oxidation and covered with colored plastic caps on top.