Overall dimensions, cm;
- length: 23.6;
- width: 17.2;
- height: 19.
Rated voltage, V: 12.
Rated capacity, Ah:
- «518»: 36;
- «520», «520i»: 44 (on request, a battery with a capacity of 55 Ah was installed);
- «525», «528»: 55.
Minimum voltage in starter mode, V: 8.5.
From model year 1980 on BMW «518» a storage battery with a nominal capacity of 44 Ah was installed as standard.