What is the difference between a NO.5 battery and an 18650 battery?

Since we know that almost all portable electronics are powered by batteries, it is not only the battery technology that differs but several variations in the same battery type. Those batteries are applicable for specific uses due to their distinct characteristics. If we take an example of such batteries, the NO.5 and 18650 batteries are at the top of the list. 

So, here we will discuss the difference between these two battery types so you can better understand which one to choose for your use case.

Dimension Comparison

Let's start by discussing the differences between these two battery types with their dimensions. These are two different battery types, which are different in size and weight. Below are the details about the differences between these two batteries.

Physical Shape

When it comes to the shape of these two batteries, there are not many differences. Both come cylindrical, with the positive terminal on the top while having the negative terminal on the bottom. Usually, both batteries' top and bottom sides are flat, but sometimes, there is a slight protruding on the positive terminal of the NO. 5 batteries.

Physical Size

One of the easiest to identify-differences between the two battery types is their size. Although both come in a cylindrical form factor, the height and diameter of 18650 batteries are higher than that of NO. 5 batteries.

The NO. 5 batteries have a diameter of 14.5mm while their height is 50.0mm. Meanwhile, the 18650 batteries are 18mm in diameter and 65.0mm in height. The difference is huge, and these two batteries cannot be mistakenly interchanged in their application.

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Weight

Another easily identifiable difference between the two battery types is their weight. NO. 5 batteries are smaller and lighter, while 18650 batteries are heavier since they are also bigger. However, it is important to note that the weight of both battery types can vary as per the materials used in their manufacturing. 18650 batteries weigh around 50 grams, while NO. 5 batteries weigh 23 grams.

Overall Form Factor

When comparing the dimensions of these batteries, the overall form factor for both will be the same since both are cylindrical with flat sides and terminals on top and bottom. However, their height, diameter, and weight will be different.

Voltage Comparison

The next comparison is about voltage; these two batteries are very different regarding voltage. This difference is crucial since the battery's voltage can be good or bad for certain use cases. So, below are the important details in voltage comparison among these batteries.

NO. 5 Battery

Usually, the NO.5 battery, also known as the AA battery, has a standard voltage rating. The typical value for alkaline AA batteries is 1.5 volts. Some variations have a lower voltage, like the NiMH (Nickel-Metal Hydride) AA batteries, which have a nominal voltage of 1.2 volts and are a type of rechargeable battery.

A new alkaline cell for the NO.5 battery begins slightly over 1.5 volts and gradually drops as it drains, getting as low as 0.9 volts or lower before it is deemed empty. Similar discharge curves for rechargeable AA variations begin slightly over 1.2 volts and decrease to about 1 volt.

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18650 battery

The 18650 batteries, mostly consisting of lithium-ion cells, have a typical nominal voltage of 3.7 volts. 3.7 volts is the most typical voltage for the lithium-ion type of 18650, although there are variations with other chemistries that could have slightly different voltages.

The voltage range of the 18650 battery is wider. Depending on the battery protection circuitry and the demands of the device, a fully charged cell can reach a maximum voltage of 4.2 volts. It will be considered discharged at roughly 2.5 to 3.0 volts.

The Impact of Voltage Difference on Applications

These two battery types' voltage differences impact their use cases and applications. NO.5 batteries are usually used for applications that require low voltage and should be lightweight. Meanwhile, 18650 batteries are good for high-power demanding applications.

Working Principle Comparison

While both these batteries provide portable power, they have differences in their working principle, which we will compare below.

Charge and Discharge Cycle Comparison

The NO.5 battery is available in both non-rechargeable and rechargeable variations. Like alkaline cells, non-rechargeable AA batteries generate electricity by a single chemical reaction; they cannot be recharged once used. NiMH or NiCd rechargeable AA batteries can be charged repeatedly. Chemical reactions that are reversible during their charge and discharge cycles enable them to repeatedly store and release energy.

The lithium-ion cell that makes up the 18650 battery functions on the theory that lithium moves from the anode to the cathode during charge and discharge cycles. Many 18650 batteries yield between 300 and 500 complete charge cycles before depleting their capacity.

Energy Density Comparison

Energy density is the energy a battery can store compared to its weight and size. 18650 batteries are based on lithium-ion technology, so their energy density is higher than NO.5 batteries. However, things can be different if the NO.5 battery is also made with lithium-ion technology, but the usage and efficiency depend on the application.

Application Differences

Due to its small size and wide availability, the NO.5 battery is a popular option for common household items like:

Toys

Clocks

Remote controls

Its usage is restricted to low or moderate power-demanding devices because of its lower voltage and variable energy densities, depending on its underlying technology.

Due to its higher energy density and voltage, the 18650 battery is frequently used in high-drain applications like:

Power tools

Flashlights

Laptop batteries

Electric cars

It is suitable for devices that require consistently high energy due to its capacity to supply more power effectively.

Conclusion

The NO.5 and 18650 batteries, each with advantages, disadvantages, and features, are essential for operating their dedicated use cases. Understanding their differences is essential for both manufacturers and users, whether it's the small size of the NO.5 battery that makes it appropriate for smaller gadgets or the powerful energy storage capability of the 18650 that makes it suitable for high-drain applications.

Users may choose one according to the best performance and longevity for their devices by understanding the advantages and disadvantages of each battery type.