In-depth analysis of notebook long-lasting battery technology

Many users buy laptops for mobile office. Mobility includes two elements: portability and long battery life. In terms of portability, major manufacturers have spent a lot of money to reduce the weight of laptops as much as possible in many aspects. In terms of battery life, low-voltage processors, LED screens and other low-power accessories effectively reduce the power consumption of the whole machine and increase battery life.

There is no shortage of laptops with long battery life on the market. However, many business people still complain that their laptops always have insufficient battery life. Even if they buy laptops with long battery life, the battery life drops from 6 hours to 3 hours in less than two months.

The problem we face is that when we first buy a laptop, the battery life is indeed very long, but after a year of use, the battery life will be greatly reduced and may even only last for half an hour. "What's the point of buying a laptop that can't maintain its advantages?" Looking at the laptop market, all laptops are like this.

Because battery technology has not advanced for many years. The capacity is sufficient, but the disadvantage of rapid loss has not been improved.

We can't help but exclaim: Laptop batteries wear out too quickly. If the only purpose of buying a laptop is to work on the go, you have to spend more than 1,000 yuan to buy an original battery. After three years, the laptop has not broken down, and the battery has been replaced several times. This price is enough to buy a mid-to-low-end laptop.

Inside a traditional laptop battery

Traditional laptop batteries are composed of lithium battery cells, control circuits, charge and discharge circuits, and shells. There are many reasons why the battery capacity is lost too quickly, and a large part of the reasons are the inherent shortcomings of this type of battery.

Battery Cell

There are two types of battery wear and tear: one is the physical wear and tear of the battery cell, which is the wear and tear of the lithium battery cell; the other is the overall wear and tear of the battery, which is the wear and tear that we can see with software. The two types of wear and tear are related, but not completely the same.

Everyone knows that there is a protection chip in the battery. The main function of this protection chip is to ensure that the battery cell will not be overcharged or over-discharged. Overcharging will cause the battery cell to overheat and accelerate loss; over-discharging will cause the reversible chemical reaction inside the battery cell to fail. The more severe the over-discharge, the greater the failure rate.

In order to avoid overcharging and overdischarging, designers will configure a monitoring program on the chip. This program will always run and record the battery's charge and discharge data, including the battery's voltage and charge and discharge current.

During discharge, the recorded voltage and current data will be converted into actual power. When the battery voltage approaches the lower limit, the monitoring program will consider the battery energy to be exhausted and compare the maximum capacity with the actual capacity. If the actual capacity is less than the maximum capacity, the monitoring program will lower the maximum capacity to avoid overcharging.

Because when charging, the chip does not know whether it is fully charged. The principle of over-discharge is similar, and the specific reduction range depends on the manufacturer's settings.

The main purpose of this design is to take care of the physical loss of the battery. Because there are multiple cells in the battery, the physical quality of the cells is good or bad. When the cells with poor physical quality begin to age, the capacity of the cells with good physical quality connected in series and parallel must also be reduced, and the overall capacity will decrease exponentially. This is the overall loss of the battery. If the maximum capacity is not adjusted according to the worst cell, then during the discharge process, it is very likely that the cells with poor physical quality will be over-discharged, causing the entire battery to be completely scrapped.

To summarize, the reasons for traditional laptop battery loss are:

1. The inherent chemical properties of the battery cell determine that the battery cell will age slowly.

2. Overcharging and overdischarging of the battery cell will seriously damage the battery cell. In order to avoid overcharging and overdischarging, the control circuit has to reduce the capacity every time. If the amplitude is too large, the capacity will be artificially reduced; if the amplitude is too small, the battery cell will increase the loss and the actual capacity will drop more sharply. This is a contradiction.

3. The structure of multiple battery cells in series and parallel determines that the overall capacity must be adjusted according to the worst battery cell.

Three years ago, Boston-Power began developing Sonata batteries. Unlike traditional concepts, capacity is not the focus of Sonata batteries. Its purpose is to manufacture batteries with extremely low losses during use.

Sonata battery cell

Sonata's battery is significantly different from the traditional 18650 battery. It is more like the square battery used in our electric meter. The following is a comparison of laptop batteries using Sonata batteries and traditional batteries:

Sonata battery only has 3 cells

It can be found that compared with traditional batteries, the number of batteries in the Sonata battery pack is reduced to 3.