What may cause the generator to stop charging?

The generator can stop charging for several reasons, and both a broken fan belt and worn down brushes contribute to this issue.

A broken fan belt can prevent the generator's pulley system from turning properly, which is crucial for the generator to produce electricity. If the generator's rotor isn't spinning at the required speed, it won't generate the necessary electromagnetic field, leading to a failure in charging the battery.

Worn down brushes also play a significant role in the generator's operation. Brushes are responsible for conducting electricity between stationary wires and moving parts within the generator. If they become excessively worn, they may not make proper contact with the rotor, leading to insufficient voltage generation or even a complete stop in charging.

Together, these two issues are common causes of a generator that fails to charge, justifying the selection of the option that indicates both A and B as valid reasons for the failure to charge.