18650 Li-Ion Battery Charge Time-Time Period and Replacement

18650 Li-ion rechargeable batteries/cells are characterized by high discharge rates and charge density. These batteries/cells are normally used in flashlights, laptops, digital cameras, and many other portable electronic devices. The 18650 cells can be used individually in a device if the energy stored in one cell is enough to power up the device for a couple of hours. But in high energy-consuming devices, these cells are often connected and put into a casing to combine the energy produced by the connected cells to power up a device. The single 18650 battery cells normally have a capacity that ranges between 1800mah to 3600mah. Milli Ampere Hours (mah) represents the amount of electrical energy stored in a battery.

In this article, I will be referring to the 18650 Li-ion cells/batteries as batteries (I guess that won't confuse you). These batteries have dimensions of 18mmx65mm and come in different colors but the most common ones are always blue. The maximum voltage that these batteries can attain at full charge ranges between 3.7V to 4.2V. In this post today, I am going to share with you all the basics you need to know about 18650 Li-ion batteries. Let's dig in…

How long does it take to charge the 18650 li-ion battery?

Charging the 18650 Li-ion battery can take about 1.5 to 4 hours depending on a couple of factors. Some of the factors that affect the charge time of these batteries include the following;

• The battery capacity: With all other factors constant, a 18650 battery with a higher capacity, will take more time to charge compared to one with lower capacity. For instance, a 1800mah battery can take about 1 to 1.5 hours to charge whereas a 3500mah battery may take about 3 to 4 hours to be fully charged using the same adapter

• The power output of the charger: A fast charger with 10W (2A and 5V) output power will charge the 1800mah battery in about an hour and the 3500mah in about 2 hours. However, using the common 5w adapters will charge the same batteries in almost twice the time.
  

• Aging: Batteries tend to lose capacity as they age. So, a battery that has been used for a couple of years will most likely charge in less time than it used to when it was still new.
  

When do you need to replace your 18650 li-ion battery?

Just like any other battery technology, 18650 Lithium-ion batteries lose their capacity after being used for a couple of years. Batteries start losing capacity as soon as you start using them. However, the loss in capacity is only recognized after about 3 to 6 months of use. A typical 18650 Lithium-ion battery can give you about 300 to 500 charge cycles. A charge cycle is counted only when you fully charge and discharge the battery. For instance, if you charge the battery to 100% and then use it till 25%. That translates into 0.75 of the charge cycle. It only becomes a full charge cycle when you use(discharge) 25% of the total energy

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on the next discharge cycle.

The amount of time it takes to get to 300 or 500 charge cycles can be between 1 to 3 years. It all depends on how much you use the battery and the capacity of the battery. Your charging habits also have an effect on the depreciation of the battery over time. So, to increase the lifetime of your 18650 Li-ion battery, make sure you adopt the right charging habits. Anything that exposes your battery to high temperatures is a bad battery handling habit. This is because high temperatures speed up the aging of the battery.

How long does a fully charged 18650 Li-ion battery last?

There is no single answer for this. The time this battery lasts depends on a couple of factors that we are going to discuss below.

• The capacity of the battery. Battery capacity is normally rated in mah (Milli Ampere Hours). With all factors constant, the higher the capacity of the battery, the more the time it will last on a single charge.  For instance, a battery with a capacity of 3500mah can last about 2 hours of nonstop use for an averagely powerful laptop. One with 2500mah may last 1.2 hours or less.

• The device where the battery is being used. Different devices consume different amounts of power. For instance, a laptop consumes more power than a flashlight. So, if these two devices have batteries with the same capacity, a laptop will consume its battery in less time than the flashlight. A 3500mah battery will last about 2 hours for an averagely powerful laptop. Such a battery can last a flashlight about 20 hours of nonstop usage. That's why flashlights have relatively smaller batteries than laptops and other higher energy-consuming devices.
  

• Age of the battery. The battery constantly loses its capacity the more it is used. This means your battery will last longer on a single charge when it is still new that when it has been used for some time. Most Li-ion batteries lose about 20% of their capacity after 1 year of usage. So basically a 3-year-old battery will have about 40% of its original battery capacity. So, a device that could last 3 hours when the battery was new, will drop to about 1 hour when the battery capacity reaches 40% of its original capacity.
  

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Conclusion

18650 Li-ion batteries/cells are among the most used batteries in many electronic devices today thanks to their high discharge rates and ability to be charged faster. The performance and durability you will get out of these batteries will largely depend on your handing habits and the conditions under which you are using the battery. Proper charging and storage of your batteries will lead to better performance and more charge cycles.

But like any other battery, 18650 batteries degrade over time. So, you should expect to be replacing your battery at least after 2 or 3 years. The period between replacement will largely depend on how long you use your battery each day. Those who use their devices heavily will have their batteries lose a significant amount of their capacity within just one year. Light device users can even use a battery for 3 years without a significant loss in the overall battery capacity.