100% battery efficiency occurs at an ambient temperature of 27°C, at -18°C the efficiency drops to 40% and slightly more than twice as much energy is required to start the engine.
Starting power (starting current) shows the battery's ability to start a car in very cold weather conditions. It shows the current in amperes that the battery delivers for 30 seconds at -18°C without the voltage dropping below 7.2 volts (the minimum level required for a reliable start). The higher this figure, the greater the starting power of the battery.
The reserve capacity indicates the time in minutes during which the battery delivers a current of 25 Amps at 27°C, i.e. the time during which the battery provides operation of all auxiliary devices in the car at night and in bad weather conditions with a faulty alternator.
In winter conditions, at temperatures below -18°C, the efficiency of battery recharging decreases due to the increase in internal resistance. During short trips in winter, the energy expended by the battery to start the engine does not have time to recover and the battery begins to wear out, gradually discharging and, eventually, failing irreversibly.
During the summer months, the engine heats up considerably during long trips, and it often happens that it is difficult to restart. Such "hot" starts sometimes consume as much energy as the batteries require in frosty weather. This is especially true for high-compression engines with a large cylinder displacement, as well as for models equipped with an air conditioning system.
Purchasing a new battery
The above indicates the importance of choosing the right battery, taking into account the engine parameters and vehicle equipment.
The first thing to look for when buying a new battery is its performance characteristics. There are three of these characteristics. The first is the NOMINAL OUTPUT VOLTAGE, which has the same value (12 V) for all those used in passenger cars, which virtually eliminates the possibility of error.
Note: When purchasing, it is advisable to test the battery with a load fork.
Second: CAPACITY, measured in Ampere/hours (A/h) and, roughly speaking, determining the reserve of electric energy contained in the battery. The choice of the value of this parameter determines how long the battery is able to provide the ability to turn the engine with the starter, or 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: STARTING CURRENT, measured in Amperes (A), i.e. the current supplied to the starter when starting the engine. The value of the starting current on batteries can be specified according to four different standards: GOST (for domestic batteries), EN (standard of the United Europe), SAE (american standard) and DIN (Germany). The latter, German standard, is the closest to our GOST and is indicated "by default" on most European-made batteries, i.e. when the standard system is not specified. The higher the starting current, the higher the speed of the starter and the greater the torque it can transmit to the engine flywheel.
Ideally, the replacement battery purchased should fully comply with the operating characteristics specified in the vehicle's operating instructions, which will ensure its maximum service life. Buying a battery with a smaller capacity can hardly be considered a good way to save money, as it will last significantly less and, in addition, may lead to unpleasant troubles associated with starting the engine in winter. You should not buy a battery with an excessively high starting current - such a hobby is associated with the risk of starter failure. If the standard battery does not provide proper engine cranking, it would be better to first change the engine oil - which will most likely lead to automatic elimination of the problem.
Recently, the country's market has been overflowing with low-quality goods and fakes. Rechargeable batteries are no exception. There are several signs by which you can distinguish an original from a fake with a fair degree of probability. First and perhaps most important: the battery case must indicate the country of manufacture and the manufacturing plant, preferably with the address. Second: the date of manufacture must be indicated, which is especially important for sealed batteries (unattended) type. The delivery set must necessarily include a technical passport, while the presence of instructions is not strictly required, which is due to the fact that in the West, batteries are almost never sold at retail, and their installation on a car is usually carried out by car service specialists. Third: high-quality batteries are distinguished by a good appearance. The case must have smooth edges, be equipped with reliable plugs and smooth terminals covered with protective caps, which are often coated with a layer of special anti-corrosion grease.
Charging the battery
Charging a failed battery should be done in accordance with the charger manufacturer's instructions.
Procedure after disconnecting the battery
1. Connect the positive cable to the battery first, then the negative cable.
Attention! The negative wire is always disconnected from the battery first and connected last!
2. Enter the radio receiver security activation code.
3. Install the on-board clock on the instrument panel.
4. Activate the steering wheel angle sensor.
5. Synchronize the sunroof drive and, if equipped, also the sliding (lamella) roof drive.
6. Synchronize the electric window lifters.