Technician A says the reserve capacity rating measures the battery's ability to operate the lights and electrical system during a generator failure. Technician B says the cold-cranking amps rating measures the battery's ability to provide current for the starter. Who is correct?

Both technicians provide valid information regarding battery performance ratings. The reserve capacity rating is indeed an important specification that indicates the battery's ability to supply power to the electrical systems of the vehicle, such as lights and other accessories, when the alternator or generator is not functioning. It represents the time duration the battery can sustain a load before it becomes depleted, making it crucial for maintaining electrical operations during a generator failure.

On the other hand, the cold-cranking amps (CCA) rating is a vital measure of a battery's capability to produce a sufficient amount of current to start the engine under cold conditions. This rating determines how well the battery can perform when starting the vehicle in low-temperature environments, where the engine requires more torque to crank.

By understanding both the reserve capacity and the cold-cranking amps, you can appreciate how each plays a critical role in battery functionality and vehicle operability, especially under challenging conditions. Therefore, both technicians are correct in their statements about the respective capacity ratings of the battery.