What could cause 0 charging voltage but normal amperage?

The correct answer indicates that a faulty DC voltmeter could cause the reading of 0 charging voltage while the amperage remains normal. If the voltmeter is malfunctioning or improperly calibrated, it may not accurately measure the voltage level even if the charging process is occurring properly. Thus, the actual voltage is present, but the measurement is faulty, leading to a misleading reading of zero volts while the current continues to flow appropriately through the circuit.

In this case, an understanding of the relationship between current and voltage is essential. A working charger could still be supplying amperage to the battery, indicating that current is flowing, even if the voltmeter isn't reporting the proper voltage level. This scenario highlights the importance of using reliable testing equipment when diagnosing electrical systems to ensure accurate readings.

Other possibilities, such as a faulty AC power source, could disrupt the entire charging process rather than simply showing a false reading on the voltmeter. An overheated battery typically results in a decrease in performance and could lead to voltage drop indications, but it wouldn't explain why amperage would remain normal. Incorrect charger settings could affect both voltage and current, not creating the specific situation of a normal current with no voltage.