How to quickly identify the positive and negative batteries

Usually there are marked above, if it is not clear, there is a multimeter to measure it, use DC voltage gear, such as the range above 20 volts, the red pen is connected to one side, the black pen is connected to one side, if the display is positive voltage, It means that the red pen corresponds to the positive pole, and the other end is the negative pole. If the negative voltage is displayed, it is reversed. If you don't have a multimeter, you can use these methods to judge:

1, from the color of the pole to distinguish, the pole is brown for the positive, the tile gray is negative.

2. Generally, the pole on the front of the label on the battery casing is the positive pole and the reverse side is the negative pole.

3. After connecting the wires to the surface terminals, they are immersed in the dilute sulfuric acid solution. The end where bubbles appear is the negative electrode, and the end where no bubbles are generated is the positive electrode.

4. Indirect light bulb in the battery poles constitutes a loop. Place a small magnetic needle under the wire that forms the loop. The direction of the magnetic needle should be perpendicular to the direction of the wire at this time. Use the right hand rule to judge that the direction of the thumb is the direction of current flow. The current flows from the positive electrode of the battery and flows back to the negative electrode of the battery.

5. Insert the two leads on the battery pole into the cut potato. The green around the wire is the positive electrode; the other pole is the negative electrode.

6. Use a high-frequency discharger to detect and compare two batteries. The one end with the same reaction has the same polarity. However, the move requires batteries of known polarity and more specialized dischargers.

7. The thick stigma is + pole (positive) and the thin stigma is - pole (negative).

8, Use salt water to judge the positive and negative poles of the battery. Connect one wire to each end of the battery, insert it into the brine, and check the wire head. The end of the battery is connected to the negative electrode of the battery, and the end with less bubble is connected to the positive battery. This trick has a few precautions. Containers containing salt water must not be electrically conductive. Generally, porcelain bowls are preferred. Further, in addition to the usual saline solution, alkali water, dilute sulfuric acid, or the like can be used as long as it can form an electrolyte solution.

9. The beaker contains copper sulfate solution, close S. After powering up for a few minutes, if red copper appears on the C carbon rod, A is positive and B is negative; if red copper appears on D carbon, A is The negative electrode and B are positive electrodes.

10. LED test method. If the LED emits red light, A is positive and B is negative. If the LED does not emit light, A is negative and B is positive.

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