Battery designation (Audi 100 C4)

If the Audi-100 has a dust filter for the body ventilation system (from 8/92) or air conditioning, the battery is located in a waterproof casing (on the right rear in the engine compartment). The battery is located on the right under the rear seat in cars where it helps to distribute the weight evenly in the Audi 100. In order to avoid having to remove the rear seat in case of an abnormal engine start, the positive terminal is located on the right rear in the engine compartment.

The following batteries are installed on the Audi-100:

• 12V/40Ah, type number 54045 (4-cylinder engines only);
• 12V/63Ah, type number 56318 (all the rest).

Battery parameters

Voltage and capacity: in the designation 12 V/40 Ah, the first number (12 V) of course indicates the voltage. Behind the slash is the current that the battery is capable of delivering per unit of time - Ah means ampere-hours. This is the nominal capacity of the battery, measured according to regulatory conditions. In practice, you should only count on ⅔ of the indicated ampere-hours; with an older battery only half.

Cold cranking current: the number 220 A or 300 A indicates the current that the battery can provide at a temperature of minus 18°C.

Type number: a five-digit number used by all German battery manufacturers to identify the battery. For the Audi-100, the corresponding numbers are 54045 or 56318. The first number (5) indicates the battery voltage of 12 V. The following digits 40 or 63 indicate the battery capacity. The last two digits indicate design features such as model, polarity, gas bleed hose and flange.