Designation
Located on the battery case, contains technical data. For example: 12 V 66 Ah 200 A (12 V is the nominal voltage, 66 Ah is the nominal capacity, 200 A is the control cold discharge current).
Nominal voltage
For all models, the general voltage is 12 V. The operating voltage depends on the battery charge level and may be lower or higher than the nominal voltage.
Nominal capacity
Battery characteristic indicating energy reserve (A/h). Reflects the energy reserve that a fully charged battery delivers at 27°C for 20 hours, provided that the voltage does not drop below 10.5 V (discharge voltage). With an on-board voltage of 12 V, the current from the battery is 2.08 A according to the formula
A (current) = W (power) / V (voltage)
Thus, a battery with a capacity of 66 Ah will theoretically provide power to the parking lights for 30 hours. In practice, if you leave the car with the lights on, the battery will be discharged in just 15 hours. The hazard warning lights will discharge the battery in about 8 hours.
Original material on the website [MercedesMAN]
Capacity
The amount of electrical energy supplied in A/h. Depends primarily on the discharge current, ambient temperature, battery charge level and overall battery condition (period of operation).
Cold state discharge control current
Determines the battery's ability to start the engine at sub-zero temperatures (measured in A). A certain discharge current taken from a 12 V battery at a temperature of –18°C, provided that the voltage does not fall below 9 V during the first 30 seconds, and below 6 V during 150 seconds.
Self-discharge
Chemical processes inside the battery cause self-discharge even when no consumers are connected. A charged battery loses approximately 0.5% of its charge daily. High temperatures, battery damage, and contamination of its cover accelerate the self-discharge process.