I don't know if you've ever experienced something similar, obviously the phone looks like it's still with %, or even 30% of the electricity, but it turns off without saying hello.
Or, the last 1% of the battery is the most durable, enough for you to watch a ten-minute ** every time?
I have to say that the matter of battery anxiety is like a midlife crisis, the more I look at it, the more anxious I become, and the more anxious I am, the more I want to see it.
When the phone was about to be turned off, I rummaged through the cabinets to find the charger, like a drug addict on TV who was looking for drugs.
Why is the battery level of a mobile phone always unpredictable? Or to put it another way, why is the phone's battery level so inaccurate?
In fact, the answer to this question is very simple, because it is difficult to estimate the remaining power of your mobile phone's battery, and even the mobile phone itself does not know the specific remaining power.
The percentage of the phone's battery level is called SOC (State of Charge), which represents the ratio of the remaining capacity of the battery to the actual capacity.
The amount of power left in the mobile phone cannot be directly measured, but must be estimated by measuring the voltage and current.
For example, when we refuel a car, the vehicle has a way to measure the height of the fuel in the tank at any time and calculate the amount of fuel remaining very accurately.
But for the battery, there is no parameter that can accurately translate into the remaining power.
So the remaining power of the battery depends on itself?
Today's mobile phones basically use lithium-ion batteries, and generally lithium batteries have three layers of 0% and 100%, and we can only see the innermost layer.
The outermost orange layer is the nominal capacity, and this layer is 0% and 100% of the real nominal battery, such as xxxah, xxxkwh but we users can't see this layer.
For battery protection, but also to protect user safety, mainly to prevent the lithium battery from overcharging or over-discharging, we have the second layer of yellow battery protection 0% and battery protection 100%, which will have an offset from 0% and 100% of the nominal capacity, such as 10%.
So 0% to 100% of the battery protection may only be 90% or less of the nominal capacity, and this 0% is 0% of the battery that will turn off your phone.
The innermost green layer, 0% (or 1%) and 100% displayed by the user, is actually a virtual 0% (or 1%) and 100% designed for user experience, and this layer has less capacity than the battery protection layer, which may only be 80% of the nominal capacity.
That is, the amount of electricity you see is the amount of electricity that the engineer wants you to see, so why show 0% or 1% to the user in advance?
This is taking into account the user's psychology, when the battery is about to run out, the early display of 1% will prompt the user to charge as soon as possible, reducing the possibility of the real power depletion.
So in reality, it is possible to show that the remaining power is 1%, but in fact there is still a certain amount of available power, and it will not be shut down immediately. You can also finish the last one, send the last message, and read the last one.
Although it seems to sacrifice 3% of the battery capacity from the display, the improvement of the user experience is huge, compared to the display of 0% or 1% after the mobile phone is turned off.
In fact, not only mobile phones, but also car fuel level display is this set of logic, after the low fuel alarm of the general car sounds, it is generally possible to drive another thirty or fifty kilometers.
So why show users 100% in advance? In fact, this is also for the user experience, which is determined by the charging characteristics of lithium batteries.
The lithium battery is charged from 0, first with a fixed high current (fast charging), and then when the voltage reaches the final adjusted voltage, it becomes a fixed voltage and a small current charging (slow charging).
This is also why the general manufacturers will advertise what 20 minutes full 60% without going too much to talk about 90% to 100% charging time issues, showing 100% to users in advance will give you a feeling of fast charging, instead of letting you wait for 20 minutes to charge the last 2%, it is better to tell you that it is full.
Of course, if you continue to plug in the charger after displaying 100%, the battery will still continue to charge up to the limit of 100% battery protection.
Then some friends may ask, why does my phone turn off quickly when there is still 10% or more power?
In fact, this is also a trick of engineers, in order to serve every battery, battery engineers have developed a battery management system (BMS).
This system is designed to manage the battery, neither overcharging the battery nor allowing it to self-discharge too much, while also controlling the temperature of the battery.
Detecting the battery level is also one of the important tasks of BMS.
The BMS system monitors the battery voltage through a chip called a fuel gauge to calculate the remaining charge of the battery.
But in actual use, the discharge state of the mobile phone is very unstable, just looking at the voltage can not accurately see the battery power, such as consuming equal power, the voltage drops fast when playing games, and the voltage drops slowly.
This is a bit troublesome: in the actual use of the battery, sometimes you need to send a WeChat; Sometimes I am swiping Weibo and flipping through the circle of friends; Wait for the circle of friends to finish, and then hit the glory of the king.
At the same time, due to small differences in the battery production process, there will also be differences in each battery. They have different degrees of aging and discharge curves. It can be said that every battery is unique.
Therefore, the BMS system will inevitably make an error in estimating the remaining power of a lithium-ion battery. And the battery level display you see is just an approximation.
So how can you monitor the battery level more accurately?
In addition to checking the voltage of the battery to determine the amount of power, the BMS system also has to go through a series of complex algorithms. And each mobile phone manufacturer has its own BMS system.
This is also why the last 1% of the battery of some mobile phones is particularly durable, while the last 10% of the battery of some mobile phones is lost quickly.
So when your phone shows 10% battery display, maybe the situation of the phone at that time is like this:
Fuel gauge: I pinch the voltage, and it is estimated that there is still 10% electricity.
BMS system: The temperature outside is over 40 today, and this big brother is still playing games, this power is not reliable! By the time we measure the voltage drop, we're afraid it's too late.
Screen display: Then show that there is 1% of the battery left, let him charge it quickly.
You: Oh my God, why is there only 1% of the battery left, hurry up and recharge.