Engineers teach you several effective methods to judge battery electrodes

This article introduces several simple methods to correctly identify the positive and negative electrodes of old batteries, so that everyone can make quick judgments when charging or testing by themselves.

Judging by the design characteristics of battery electrodes

Generally, when commonly used storage batteries are manufactured and designed, the thicker end of the battery pile is the positive electrode, and the thinner end is the negative electrode. You can also identify the color of the battery pile, where the positive electrode pile is dark brown, and the negative electrode is dark gray. In addition, some batteries use English letters to indicate the positive and negative marks, that is, P indicates the positive electrode and N indicates the negative electrode. This must not be mistaken when repairing and charging.

Use the multimeter voltage block to measure

The multimeter can be set to the DC position, and the two test pens are connected across the two electrodes of the battery. If the battery displays a normal voltage value, it proves that the electrode touched by the red test pen is the positive electrode of the battery, and the black test pen is the negative electrode. Sometimes, if the battery is measured to have no normal voltage, the weak amount of electricity stored in the battery can be measured to make a judgment. When the two test pens touch the battery electrodes, if the needle shakes slightly to the right, it proves that the red pen is the positive electrode of the battery and the black test pen is the negative electrode. But if the multimeter pointer shakes to the left (the needle is reversed), it proves that the red pen touches the negative electrode of the battery.

Identification by short-circuiting the wire

Connect two copper-core power cords across the electrodes of the old battery to be tested, pour the normally configured electrolyte (concentrated salt water) into a glass teacup, insert the two ends of the power cord into the teacup respectively, and place them on the edges of the two sides of the glass (the two wires cannot touch each other in the cup), and then observe the bubbling of each lead end in the electrolyte. If there are obvious and more small bubbles on one end of the wire, it means that the end of the power cord connected to the battery is the negative electrode, and the end with fewer and less obvious bubbles is the positive electrode of the battery.

Determination using a rectifier diode

The rectifier diode in the power stabilizer has unidirectional conductivity. You can find a rectifier diode and a 40w incandescent lamp. Then connect them in series in the order of one battery column → diode + end → diode - end → incandescent lamp → another battery column to form a series circuit of electric lamps. At this time, if the incandescent lamp in the circuit is ignited and emits light, it proves that the connection between the diode extreme and the battery column is the positive electrode of the battery, and the other end is the negative electrode of the battery.