Final answer:
Tech A is correct about vehicles having a specified CCA rating for batteries, while Tech B is incorrect about the reserve capacity indicating the number of engine starts. The CCA measures the battery's ability to start an engine in cold temperatures, and a higher CCA indicates less internal resistance.
Step-by-step explanation:
Tech A is correct in saying that all vehicles have a specified Cold Cranking Amps (CCA) rating for the battery, which refers to the number of amps a battery can support for 30 seconds at a temperature of 0°F until the battery voltage drops to unusable levels. This rating is essential for ensuring that the battery can start the engine in cold temperatures.
Tech B, however, is incorrect. The reserve capacity of a battery does not indicate how many times the engine can be started by the battery. Instead, reserve capacity is a measure of how long a fully charged battery can deliver a specified current (usually around 25 amps) before dropping to a specified cutoff voltage (usually 10.5 volts), typically measured in minutes.
Regarding the internal resistance of batteries, the lower the internal resistance, the higher the CCA rating tends to be. This is because a lower internal resistance allows for more efficient current flow. Therefore, between two 12-V automobile batteries rated at 600 and 850 CCA, the one with 850 CCA will have the smallest internal resistance.