Calcium batteries are standard lead-acid automotive batteries which are used for basic SLI (starting, lighting, and ignition) application. Calcium batteries are fitted to vehicles that do not have idle stop start technology, smart ECU controlled alternators or do not require cycling performance.

As pure lead is not strong enough alone to withstand the operating conditions, calcium is added to the plates of these wet lead acid batteries to significantly improve the mechanical strength of the lead. Calcium is preferred over the previously commonly used antimony because of decreased electrical resistance, better resistance to corrosion, reduced gassing and reduced water usage - enabling a maintenance-free design.