What is the charge cycle of a battery (and how does it affect its useful life)

charge cycle voltage

One of the key factors that determines the life of a cell phone battery is the number of charge cycles. This is a concept you should understand to increase long-term battery life.

Commonly, the Lithium-ion batteries that come in today’s mobiles last 300 to 500 charge cycles. When that limit is reached, batteries can lose around 20% of their capacity, depending on the manufacturer. This means that your charge will last less time and will eventually need to be replaced.

To maintain battery capacity over time, it is important to consider this factor. You have to understand when or how a charge cycle is completed, what to do to extend its duration and therefore extend the life of the battery.


When a charge cycle is completed

Charge cycle of a Lithium Ion battery. Image: Apple.com Charge cycle of a Lithium Ion battery. Image: Apple.com

Charge cycle of a Lithium Ion battery. Image: Apple.com

A first concept to know is when a charge cycle is completed.

Do not be confused by the term. Apple indicates that a charge cycle completes when 100% of the battery has been used or discharged .

He clarifies that this process does not necessarily have to be uninterrupted. If 75% of the battery is consumed in one day and recharged at night, a consumption of 25% the next day would already add up to a total of 100%, which would count as a charging cycle.

In other words, a charging cycle could be completed in the same or multiple days.

Things that affect charging cycles

Using the device

From what has been said before, obviously the duration of the battery charge cycles will depend on the use of the device. The more intense the use, the faster the battery charge will finish and the faster a charge cycle will be consumed.

You might think this works like this, regardless of upload and download habits, and there is nothing that can be done.

However, Battery University advises on this: the smaller the discharge ( low Deep of Discharge or low DoD ), the longer the battery will last. It says you should avoid full discharges and charge the battery more often between uses.

Regarding the subject, in Wikipedia it is explained that periodically discharging the battery could impair its effectiveness. Recommends that the load not drop below 15%.

Charge level

charge cycle voltage charge cycle voltage

Number of charge cycles of a lithium ion battery based on charge / voltage level. Image: Battery University

Charging cycles are also affected by the level of battery charge.

Generally, when a battery reaches 100% level, it takes a value of 4.20 volts per cell. If the battery always had this value, it would have a useful life of 300 to 500 charge cycles.

The battery voltage increases or decreases as the charge level rises or falls. Reducing this voltage by just 0.1 volts per cell could double battery charge cycles. With a voltage of 3.92 volts per cell (corresponding to a 58% charge) a lifespan of between 2400 and 4000 cycles could be obtained.

Considering that, the best thing would be to keep the battery at a level of 40% and 70%. This would balance between a time of acceptable duration and an extension of the useful life.

The heat

It also indirectly affects charging cycles.

A high temperature in the battery increases the voltage and consequently reduces the charge cycles due to what has been said before.

Even storing batteries in a hot environment can reduce their capacity over time.

It is recommended to prevent the phone from getting too hot, either due to its intensive use or the environment.


This article only applies to Lithium ion batteries that are currently used by cell phones and laptops.

It affects Li-Ion or Li-Po batteries in the same way , since normally any of these two terms that appear in the technical specifications of a device refers to a lithium-ion battery.

Li-Po is practically the same as the Li-Ion battery, only with a different “packaging”.

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