To understand where the positive and negative terminals are on a battery, simply look at the markings. Typically, the positive terminal will be located where the contact is shaped like a bump. There's also a "+" symbol on the side. If you look at the other flat end, you'll see a "-" symbol. These symbols help you avoid confusion and correctly insert the battery into your device.
What happens if you confuse the positive and negative terminals on a battery?
It's a very unfortunate situation when this happens to you. At best, the device won't work, and at worst, it could fail. Not all electronic devices have reverse polarity protection. Sometimes, the batteries can simply die.
You can also determine the battery's polarity using a multimeter. Just make sure the leads are in the correct positions. If, after you touch the probes to the battery terminals, the display shows a minus sign before the number, you need to swap the probes. The red lead connected to the DC power source is the positive lead, and the black lead is the negative lead.
Thus, the tester will show with 100% probability where each pole is located.
When inserting the battery into the device, be careful! The polarity markings on the battery case and the battery must match.
Read also: How to check a battery with a multimeter?
