What tool should a technician use to troubleshoot a slow drain on a battery?

To troubleshoot a slow drain on a battery, using an ammeter is highly effective because it measures the current flowing from the battery. When you suspect a slow drain, you can connect an ammeter in series with the battery. This allows you to see how much current is being drawn from the battery when everything is off, providing a direct measurement of any parasitic drain.

An ohmmeter is designed for measuring resistance, and while it can help identify short circuits or opens in a circuit, it cannot measure current flow, which is essential for diagnosing a slow drain. A voltmeter measures voltage, which, while important for assessing the overall health of a battery, does not provide information on current draw. A test light can indicate a circuit’s operational status but does not provide quantitative data on the amount of current flowing, making it less effective for diagnosing the specific issue of battery drain. Therefore, an ammeter is the most useful tool for pinpointing excessive current draws that lead to battery drain.