This SAE Recommended Practice applies to 12 V storage batteries which operate in a voltage regulated charging system. It simulates heavy-duty applications by subjecting the battery to deeper discharge and charge cycles than those encountered in starting a vehicle. The deeper discharge and charge cycles in service may come from a combination of the following conditions: a.) Frequent occurrences of total electrical load exceeding the alternator output; b.) Frequent occurrences of battery system supplying the electrical loads when the engine is not operating; c.) Frequent occurrences of prolonged vehicle storage combined with high vehicle key-off loads.

Batteries will be classified into two types for this life test. Type 1 applies to batteries with reserve capacity of 200 min or less. Type 2 applies to batteries with reserve capacity greater than 200 min. ("C" value for Type 1 equals 25.0; "C" value for type 2 equals 50.0.)