How to Distinguish the Positive and Negative Poles of a Car Charger?

[DelCaroline]

You can directly use a multimeter to measure. Under normal indication, the red probe represents the positive pole. Alternatively, you can connect a 1.5V small battery and a 6V small bulb in series with the charger. Observe the bulb brightness, then reverse the battery's positive and negative poles and check the bulb brightness again. Another method is to open the car charger and use the filter capacitor and circuit lines to determine. The filter capacitor's pins are marked with positive and negative poles. Generally, the red wire is the positive pole, and the black wire is the negative pole.