Youfei Electronic Engineer talks about battery power display!
What is smart battery?
What is smart battery? Because it knows the core. It has been hundreds of years since the emergence of batteries. Simple protection functions can not meet the needs of modern society. Now, for high-end batteries, users need to know how much power, remaining time, current voltage, current, temperature and other information the battery has left.
As early as 20 years ago, the IC of the electricity meter did not appear. The earliest design is that the single-chip microcomputer detects the battery voltage through the ad port to determine the remaining electricity of the battery. However, this method of voltage detection is accurate for the small current discharge of the battery and the battery electricity error. Because the voltage drops gradually, as long as several fixed voltage points are set to judge, such as 100%, 75%, 50%, 25%, 10% The voltage corresponding to the capacity is enough, as shown in Figure 1. If the large current is discharged, it is not suitable. Because the large current is discharged and the voltage fluctuates greatly, just like the early mobile phones, there are still two grids of electricity before calling, which directly indicates that the power is insufficient during the call Please charge it in time (as shown in Figure 2), which will cause misunderstanding to consumers. They say that this is a problem with your product. It is clear that there are still two grids of electricity. Why can't you call? Why can't you ask for a return and exchange? In fact, this has nothing to do with the design scheme. At that time, there was only such a scheme, there was no other scheme to choose from, and the battery material was not so stable And mature.
Figure 1: with the progress of science and technology, the battery materials are becoming more and more stable. The battery management IC is springing up, innovating and improving. The most representative international companies are Texas Instruments, Meixin, etc. Many high-end products in the market will use electricity meter IC, what is electricity meter? As the name implies, it is the calculation of battery power. It calculates the remaining capacity and working time of the battery. The meter IC integrates measurement algorithms, such as Coulomb counting, impedance tracking, Kalman filtering and other algorithms. It can calculate the remaining capacity of the battery through current, voltage, temperature, times of use and other parameters, and it can support how long the battery can be used. When the battery power is low, it reminds the user of charging Electricity, common electricity meter IC includes bq27541, ds2781, ds2782, bq40z50, etc. Why is the battery of the charge meter IC so expensive? If you don't understand the production process of smart battery, you may just have a one-sided understanding that the battery board, line and battery comprehensive tester will be delivered after passing the test. In fact, the production of smart battery is far from so simple, much more complex than this. First of all, starting from the battery protection board, how to let the main board know the battery information, then the protection board will be designed as bandpass The main board can be contacted through communication, so that what kind of information the main board needs can directly read the information stored in the electricity meter. Secondly, after designing the protection board, it needs to learn Chem according to the battery core required by the customer_ ID, what is Chem_ ID? ID is the aging data of many battery models integrated by TI company, and then the type of each battery is numbered. We learn that this ID is to match the aging data of one of the batteries, so that the battery's future power model is calculated based on the aging curve corresponding to this ID. It's not easy to learn this ID. first, set it according to the parameters of the battery, then calibrate the voltage, temperature and current; then fill it with 0.2C for 2 hours, then discharge it with 0.2C to over discharge protection for 5 hours; after getting the data, upload it to the official website of Ti, and the official website of Ti will return a series of ID numbers, select the appropriate ID number, and write it into the electricity meter IC, Then, the battery and the protection board shall be subject to the aging test of electricity calculation. The battery and the protection board shall be charged at 0.2C for 2 hours, and then discharged at 0.1C for 5 hours. After two cycles, the latest full charge capacity, battery impedance update and state change will be obtained. For example, the protection board of bq40z50 in two strings will be updated to 0055 and update after successful learning
The status is updated to 0e, and after learning, as shown in Figure 3 and Figure 4, batch files are exported for batch use. After protecting burn-in aging data, after battery assembly and production, aging test of charging and discharging cabinet is required, aging battery capacity. The whole production process is very complex. Not only is the price of a single ammeter IC 10 times more expensive than that of a general protection IC, but also the battery assembly process is several times more complex. So why is the battery with communication so expensive, but you have your advantages. The device can accurately get the battery voltage, temperature, current, remaining capacity, remaining time and other information, so as to avoid shutting down the device Cause damage.
The development trend of battery in the future must be all electric meters. Now, no matter what industry wants to maximize the performance of battery, from automobile battery to ordinary wearing equipment, it can accurately estimate the remaining capacity and time of battery, because the battery has already penetrated into our life, and many things in our life can't leave the battery But we all have a disease called battery anxiety. Like our cell phone batteries, we worry about not using enough batteries every day. What should we do if we are on a business trip? What if I can't find a charge? 50% of the battery is left. Do you want to charge it? How long can the battery last? This is a common problem in our current life. If we calculate the battery information accurately, then I believe our anxiety will be relieved!
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