Dual-Purpose Battery Specifications
Cold Cranking Amps (CCA); the amps a 12V battery can discharge for 30 seconds at -18°C / 0°F while maintaining its voltage above 7.2 volts. Because lead-acid batteries produce more energy at higher temperatures, batteries are also rated in Cranking Amps (CA), similar to CCA but measured at 0°C / 32°F and Marine Cranking Amps (MCA), similar to CCA but measured at 27°C / 80°F. Engine size, type, and ambient temperature determine what size of cranking battery is required. Higher cranking power is required for cold temperatures, diesel engines, or high-compression gas engines where high cranking voltage must be maintained for the fuel ignition systems to function. This requires maximum Amp Hours (AH) or Reserve Capacity (RC): Minutes a battery can maintain a load of 25 amps before it drops to 10.5 volts (at 27°C / 80°F).
Dual-purpose batteries must consistently deliver reasonable Cold Cranking Amps, operate at high and low temps and withstand vibration. With the engine off, Reserve Capacity (RC) is required to support moderate electric loads such as electronic equipment, radios, house lights, bilge pump, small inverters, etc. Dual-purpose batteries can be designed with micro-cycle (17.5% Depth of Discharge - DoD) or high cycle (30% Depth of Discharge - DoD) life characteristics. Typically, the higher the cycle life ability, the lower the CCA rating will be in a dual-purpose battery. A battery with high CCA, High Reserve Capacity “and” long life should be viewed with suspicion.