How to technically extend the life of lithium-ion batteries?

This example explores the first-generation electronic thermostat, which is MCU-based, but requires an additional external integrated circuit to measure temperature, as well as an external oscillator and battery monitor to wake up the MCU. In addition, the thermostat requires expensive manual calibration. The above-mentioned first-generation solution requires a current greater than 20a, the battery life is only 2-3 years, and the total IC cost exceeds 2 US dollars. It needs to be redesigned to extend battery life and reduce costs. Regarding the electronic thermostat studied in this article, the effective duty cycle is extremely low, because it is in the standby state most of the time, and the automatic wake function of the system maintenance performs daily affairs. Unlike the setpoint potentiometer, the temperature of the thermostat is measured every few seconds. According to the temperature comparison and the selected operating mode, the system turns on or off the cooling and heating function. When the temperature is within the expected range, the system does not perform any operation. The important goal of the redesign of the thermostat is to minimize the standby current. To this end, we chose ultra-low power consumption single-chip microcomputers, and ran the power consumption intelligent software. The single slope conversion charges the capacitor at a fixed point, and measures the discharge time by measuring a known reference resistance with a comparator integrated in the MCU. The system repeats this cycle for the unknown resistance. The integrated timer automatically captures the discharge time, saves power, and allows the CPU to be turned off and measured during the discharge cycle. The single slope technique follows the principle of proportionality, which eliminates charge voltage, charge capacitance, and complex exponential equations related to RC discharge. The measurement time is proportional to the discharge resistance, and its accuracy is the same as the sensor's reference resistance, thus eliminating the need for expensive calibration procedures. The current required to trigger the low-pressure heating/cooling relay is a 100mA current pulse of 10ms. According to statistics, the relay may be triggered 16 times per hour. Therefore, the effective duty cycle of the relay is 0.0044%, which is approximately equal to the system current 4.4a. From a battery point of view, we are concerned about the 100mA current required to trigger the relay. The battery of the first-generation electronic thermostat was originally a CR2032 button lithium-ion battery. The battery has a rated capacity of 200mAh, its inherent ultra-low leakage rate is less than 1% per year, and the discharge curve is very flat. Both of these characteristics are ideal for extending battery life. The problem with the CR2032 is that its impedance is very high, about 20, so it prevents the battery from supplying 100 mA to the relay needed to trigger the cooling and heating system. Although the required 100mA pulse current can only last for 10ms, it still far exceeds the power of a button battery. Designers have considered using large-capacity capacitors (for cost considerations, electrolytic capacitors are the only choice), but gave up due to their high leakage. Replacing the battery in the MCU application is a hassle, because the power supply noise appears from the mechanical contact with the battery line. Undervoltage situations often occur during battery replacement, and the power supply voltage is not completely reset, resulting in random fault operations. An additional reset current or power supply voltage monitor (SVS) can provide under-voltage protection, requiring the MCU to perform a complete reset when the voltage is below the safe operating range. SVS protection requires power, cost and board space. Choosing an ultra-low-power MCU as an alternative method can achieve zero power consumption under voltage reset (BOR) protection. The ultra-low-power MCU provides in-system programmable (ISP) flash memory and embedded simulation logic for the electronic thermostat. These functions perform normal debugging of the MCU in the application program by using the test and reset/NMI pins. This allows rapid development as well as flexible customization and emergency code changes. We can program the microcontroller code in the flash memory during the production process, which can reduce complicated application programming, thereby reducing costs and improving product quality. If necessary, the equipment can be electronically calibrated during the production process and stored in flash memory. Since the flash is an isp style, as a future function, the MCU can also record data during normal operation. The use of minimal power consumption to achieve absolute long battery life is a common design requirement for many deeply embedded applications. A battery electronic thermostat based on a microcontroller (MCU), and each microampere (A) current has been carefully designed. Statement: Some pictures and content of articles published on this site are from the Internet. If there is any infringement, please contact to delete Previous post: Analyze the impact of electrode thermal stability on the safety of lithium-ion batteries