Many of us notice that the efficiency of the rechargeable battery we use daily, whether in a phone, laptop or other devices, decreases significantly after a period of use. The battery no longer holds up as long as it did when it was new, and the charging runs out quickly and lasts for a shorter time. This may be due to manufacturing quality issues at times, but even if the battery is from a reputable brand, the cause may be due to the nature of some types of batteries, such as Lithium-ion batteries used in most smartphones and laptops today, which degrade over time with usage along with some wrong practices while using those batteries.
In this article, we will review some of the main reasons for the decline in the efficiency of rechargeable batteries and ways to avoid it to keep the battery in good condition for as long as possible.
First, Types of Rechargeable Batteries
Firstly, it is important to note that this article does not focus on smartphone batteries, but rechargeable batteries in general. There are several types of rechargeable batteries, each with different uses and expected lifespans.
In general, a battery is made up of one or more cells, its main task is to store electrical energy and then discharge it for use in operating various devices and equipment as needed. The first battery that came into existence was invented by the Italian physicist Alessandro Volta in 1800, which was a simple battery consisting of electric poles and electrolyte. The chemical reactions inside the battery cell allow the flow of electrons through the electrolyte from the negative pole of the cell to the positive pole, resulting in the creation of an electrical voltage that passes an electric current inside the battery.
Batteries are divided into two main types, one is not rechargeable (not our topic today), and the other is the rechargeable type, which includes several subtypes, including:
Nickel Cadmium Batteries
The Nickel Cadmium battery is one of the oldest types of rechargeable batteries in use, known for its high reliability and durability. It is still used today as they can be recharged approximately 1000 times before they start to lose their efficiency.
Nickel Metal Hydride Batteries
This type is a relatively new form of the Nickel Metal Hydride batteries. The battery has a higher energy storage capacity compared to Nickel Cadmium batteries and is used especially in satellites and space applications.
Lithium-ion Batteries
Lithium-ion batteries are the most commonly used today in electronic devices such as smartphones and laptops. They have a higher energy density, smaller size, and can provide higher voltages compared to other types of batteries. They are less susceptible to issues like memory effect and self-discharge compared to Nickel batteries.
Secondly, Reasons for Deterioration of Rechargeable Batteries
1) Memory Effect
The phenomenon known as “Memory Effect” can occur in some rechargeable batteries such as Nickel Cadmium and Nickel Metal Hydride when the user recharges the battery before it is completely drained. This can lead to a memory effect, causing the battery to think that the same amount of energy is needed to fill the battery’s capacity in each subsequent charge, repeating the incomplete charging cycle each time the battery is recharged.
If you are using Nickel Cadmium batteries, the best way to prevent the memory effect is to calibrate the battery by fully draining it to a level of 1 volt per cell, then fully recharging it. It is also advised to store the batteries away from high temperatures and high humidity, in a dry and cool place to protect them from damage.
2) Full Charging and Full Discharging
Many people believe that keeping a rechargeable battery in good condition by charging it to 100% and using it until the energy is completely depleted, i.e., reaching a 0% energy level, is beneficial. However, this may be true for some older types of batteries, but it does not apply to newer types of batteries such as Lithium-ion batteries found in most smartphones. Overcharging or fully discharging can lead to inefficiency and shortened lifespan of the battery.
Lithium-ion batteries, for example, should not be fully discharged or fully charged for optimal performance. It is recommended to charge them to around 80-90% and use them, then start recharging before the energy level drops to about 20%.
3) Overcharging
Leaving your device connected to the power socket for hours even after the battery is fully charged can lead to overcharging. Some advanced devices have safeguards to prevent overcharging by stopping the flow of electricity to the battery once fully charged. However, if these protections fail, continuous flow of electricity after full charge can lead to reduced battery efficiency and lifespan.
These methods ensure user safety, but what if these protection measures fail in limiting the continuous flow of electricity after charging is complete? What impact does that have on the battery’s efficiency and lifespan?
If a device such as a Lithium-ion battery is connected to a power socket to charge it, the battery will draw a constant current until the voltage inside the cells reaches 4.2 volts. Continuous flow of electricity after charging the battery completely can lead to an increase in voltage inside the cells, decreasing battery efficiency and its expected lifespan.
The excess energy may also generate more heat, affecting the chemical reactions inside the cells and creating unstable chemical conditions that may lead to gas leakage in some types of batteries or increased pressure inside the battery. All of this reduces the expected lifespan and efficiency of the battery and could lead to its burning or complete damage.
4) Self-Discharge
Self-discharge phenomenon occurs in rechargeable batteries when chemical reactions between the unconnected electrodes reduce the stored electrochemical charge when the battery is not in use, affecting its full capacity and performance during usage.
The self-discharge rate of a battery depends on several factors such as battery type, charge status, charging current, and ambient temperature. Lithium-ion batteries have a lower self-discharge rate compared to other types, which may self-discharge at different rates each month.
Storing rechargeable batteries at low temperatures reduces the self-discharge rates, preserving the initial stored energy within the battery.
5) Excessive High Temperatures
Operating a rechargeable battery at high ambient temperatures will decrease the electrical resistance of the battery, allowing more electricity to flow through the battery. This can provide a higher amount of energy to the device, but what is the effect on the battery’s efficiency and expected lifespan?
