22 Years' Battery Customization

18650 Battery Which Side Is Positive

Aug 18, 2020   Pageview:85480

Do you still get confused regarding which side of the battery is positive, and which is negative? If your answer is yes, then don’t be embarrassed. Hundreds and thousands of other people in the world still cannot tell which side of a cell is the positive or negative side.

If you still want to know more, check the following two articles:Battery Type 18650: Introduction, Application, and Performance, 18650 Battery Cell-Recharge, Care, and Safety.


So, here we will explore the sides of popular 18650 batteries.

What Side Is Positive And Negative On A 18650 Battery?

As the 18650 batteries are one of the most popular types of lithium-ion batteries, you must know how to use them. Unless you want your cell to explode, recognizing the positive and negative sides of the battery is essential. They are commonly used in flashlights, laptops, and many high-drain devices for their superior capacity and discharge rates.

In a 18650 battery, the positive electrode has a coating of aluminum cobalt oxide. There are some other components available with the aluminum foil as well. The negative side is traditionally made from carbon materials like graphite and silicon. The 18650 batteries are the cylindrical cells, and all the cells are constructed with a basic design. Typically, they have a positive terminal nub on one side and a flat terminal at the other end.

The cell with a nub on the positive terminal is called a button top, and the battery without a positive nub is called a flat top. And this is the thing that gets people confused about the positive and negative sides. When there is a button top on the positive side, it gets easier for the consumers to identify the negative and positive sides. To understand which side is positive or negative, you can look for the signs as below:

18650 14.4V 3400mAh Lithium Battery Panasonic Battery for Handheld Device with SMBUS Communication
Handheld Device 18650 14.4V 3400mAh Lithium ion Battery Pack Battery Cell:18650-3350mAh-3.6V With SMBUS Communication

· Look for the Logo on the cell. Generally, the Logo is given in such a way that the left side of the logo is positive, and the right side is negative.

· Check out the shape of the end, and if the end is raised even a little bit, then it is the positive side. The negative side will be entirely flat.

· Use a multimeter every time you use the cell. When you place the point on the positive side, the line on the multimeter will display the "+" sign on the red line, and "-" on the black line. When the negative sign is touched, the results will be opposite, i.e. "-" on the red line and "+" on the black line.

· If you can see a clear concave ring at one end of the battery, then this means that it is the positive side and the other end is negative.

These tips will let you know how you can identify the positive side of a 18650 battery.

18650 10.8V 6600mAh Lithium Ion Battery Panasonic Battery for Medical Device with SMBUS Communication
Medical Device 18650 10.8V 6600mAh Lithium Battery Pack Battery Cell:18650-3350mAh-3.6V With SMBUS Communication

How Do You Know Which Way To Put 18650 batteries In?

Yes, this question needs to be answered, as well. The other confusion is how to put the batteries inside the device or equipment.

Generally, you will see that there is some coil arrangement on one side of the batteries. This arrangement is provided to ensure that there is maximum contact of the device with the negative terminal which has the flat end. The nub in the cell will provide pressure to the negative flat side.

It is advised that when you are inserting the 18650 cells in a device, you should confirm that right cells are used. These batteries are similar to AAA batteries. As a result, the consumers confuse them both and use them interchangeably. But this should be avoided as some 18650 batteries come without protection, and they might result in a short circuit.

How Do You Protect 18650 Battery From Short Circuit?

Lithium-ion chemistry is dangerous if it is not handled correctly. The batteries release high energies, and they have several risks. The 18650 batteries are vastly used in households, and they have caused many accidents. Sometimes, it is the fake batteries, and sometimes the consumer negligence cause lots of troubles. When the internal pressure inside the battery increases, if they are overcharged, they exceed the acceptable value, and the battery short-circuits. If there is more than one cell combined, then this will create a chain reaction, and an explosion might happen.


So, you need to protect your 18650 battery at all costs. The good thing is that these batteries come in both variants, protected and unprotected. The best move will be to buy a protected battery always.

When the internal short-circuit occurs, heat is generated, and high-pressure gas is released, which cannot escape through the exhaust valve resulting in an explosion. Therefore, you need to follow the guidelines mentioned below:

· Use a branded 18650 charger to charge the battery. Most of the short-circuit cases happen during the charging process. Instead of buying the cheaper charger, always get an authentic charger no matter how expensive it is.

· Ensure that your 18650 battery has overcharge protection so that if the charge goes over the value, the charging state will be terminated. This will avoid the pressure increase in the cell.

· Consider the over-discharge protection as well to prevent the voltage drop of the battery beyond the point where the circuit becomes incapable of charging again.

· Short-circuit and over-current protection must be present inside the battery to avoid conditions that result in short-circuit.

When Lithium battery chemistry is considered, the possibility of an explosion cannot be denied. That’s why the manufacturers are always trying to improve the safety and protection features in the batteries. And 18650 is a big name in the lithium battery market; hence, they need to be much safer. But it is not just the manufacturer's responsibility to keep them safe. As a consumer, you need to be aware of the risks and precautions, as well. Your minor mistake might lead to a big accident. So, whether it is inserting the batteries into the devices or charging the 18650 battery, having basic knowledge is necessary.


Leave a message

Contact Us
Your name(optional)

* Please enter your name
* Email address

Email is required. This email is not valid
* How can we help you?

Massage is required.
Contact Us

We’ll get back to you soon