Several 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.

1. Judge based on the design characteristics of the battery electrode

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, the positive and negative marks of some batteries are represented by English letters, that is, P represents the positive electrode and N represents the negative electrode. This must not be mistaken when repairing and charging.

2. Use the voltage range of the multimeter 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. The black test pen is the negative electrode. Sometimes, if the battery does not have a 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.

3. Use wire short circuit for identification

Connect two copper core power lines across the electrodes of the old battery to be tested, pour the properly prepared electrolyte (concentrated salt water) into a glass cup, insert the two ends of the power line into the cup, and place them on the edges of the glass (the two lines should not touch each other in the cup), and then observe the bubbling of the lead ends in the electrolyte. If there are more and more small bubbles on the end of a certain wire, it means that the end of the power line connected to the battery is the negative electrode, and the end with fewer and less obvious bubbles is the positive electrode of the battery.

4. Determination using a rectifier diode

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