A method for monitoring the charge of a button cell

Abstract

The present application relates to the field of electronic technology, disclose a button cell power monitoring method, to solve the present stage battery power monitoring method cannot accurately monitor button cell power and monitoring circuit is too complex to affect the service life of the battery technical problem; The present application first determines the corresponding battery discharge curve under different temperatures, can effectively improve the battery power measurement accuracy in the environment of temperature change, simultaneously according to the change trend of discharge voltage in discharge curve, the discharge process is subdivided into three discharge stages, and the corresponding battery remaining capacity calculation relationship of three discharge stages is obtained according to the discharge curve relationship, in the actual measurement of battery power, according to the specific circumstances, the corresponding calculation relationship is called to monitor the battery remaining capacity; And the present application uses general sensor system circuit to measure the battery power, realizes in the case of not increasing the peripheral circuit, improves the accuracy and effectiveness of the battery remaining capacity monitoring.

Description

Technical Field

[0001] This invention relates to the field of electronic technology, and in particular to a method for monitoring the charge of a button battery. Background Technology

[0002] With the development and popularization of the Internet of Things (IoT) and smart homes, various environmental sensors based on wireless communication are being used more and more widely. Wireless sensors are generally small in size and low in power consumption, and cannot be powered by wires, so most of them are powered by button batteries, which can maintain a working life of several years. Sensors need to monitor the button battery's discharge voltage, remaining charge, and other information in real time so that they can send an alarm message to the wireless receiver in time when the battery is low, reminding the user to replace the battery. Currently, methods for detecting button batteries include estimating the battery's lifespan based on the product's power consumption and the button battery's nominal capacity. However, due to the uncertainty of battery efficiency and the existence of self-discharge, the calculated charge can be inaccurate. Other methods include measuring the battery's internal resistance and estimating the charge based on that resistance. The drawback is that the battery's internal resistance is unstable in a short period of time and varies within a certain range, leading to inaccurate charge calculations. In addition, there are techniques that use external circuitry to measure parameters such as the battery's internal resistance to calculate the charge, but this increases system power consumption and shortens battery life. If accurate battery charge monitoring can be achieved while ensuring battery lifespan, the aforementioned problems with inaccurate charge monitoring can be solved.

[0003] In response to the above situation, there is an urgent need for those skilled in the art to provide a technical solution that accurately monitors battery power while ensuring battery lifespan. Summary of the Invention

[0004] This invention provides a method for monitoring the charge level of a button battery, which solves the technical problem in the prior art that it is impossible to accurately monitor the charge level of a button battery and ensure its lifespan.

[0005] To solve the above-mentioned technical problems, the technical solution proposed by this invention is: a method for monitoring the power of a button battery, comprising the following steps:

[0006] S1: Establish at least two non-overlapping temperature ranges and obtain the discharge curves of the button cell corresponding to each temperature range.

[0007] S2: Divide each discharge curve into three discharge stages, and fit the calculation relationship between the remaining charge and discharge time corresponding to each discharge stage curve.

[0008] S3: Construct a battery power monitoring circuit, query the discharge curve under the matching temperature range based on the current ambient temperature, then find the discharge stage of the current discharge voltage in the discharge curve, and then calculate the remaining battery power according to the calculation formula corresponding to the discharge stage.

[0009] Furthermore, the discharge curve is the discharge curve at the center temperature of each temperature range.

[0010] Furthermore, the three discharge stages include: the initial discharge stage where the discharge voltage monotonically decreases as the discharge time increases, the final discharge stage, and the stable discharge stage where the discharge voltage remains constant.

[0011] Furthermore, the process of establishing the computational relation includes:

[0012] Establish the calculation formulas for the discharge voltage V and discharge time t corresponding to the three discharge stages within the temperature range:

[0013] Initial stage of discharge: V1 = f(t) v1 ), Vmin1≤V1≤Vmax1, t0≤t v1 ≤t1; where V1 is the discharge voltage during the initial stage of discharge, t v1 t0 represents the discharge time during the initial stage of discharge; Vmin1 and Vmax1 represent the minimum and maximum voltage values ​​during the initial stage of discharge, respectively; t0 represents the start time; and t1 represents the maximum discharge time during the initial stage of discharge.

[0014] Stable discharge phase: V2=f(t) v2 ), Vmin2≤V2≤Vmax2, t1 <t v2 ≤t2; where V2 is the discharge voltage during the stable discharge phase, t v2 t2 represents the discharge time during the stable discharge phase; Vmin2 and Vmax2 represent the minimum and maximum voltage values ​​during the stable discharge phase, respectively; t2 represents the maximum discharge time during the stable discharge phase.

[0015] Final stage of discharge: V3 = f(t) v3 ), Vmin3≤V3≤Vmax3, t2 <t v3 ≤t3; where V3 is the discharge voltage t at the end of the battery discharge process. v3 t3 represents the discharge time at the end of the discharge phase; Vmin3 and Vmax3 represent the minimum and maximum voltage values ​​at the end of the discharge phase, respectively, and t3 represents the maximum discharge time at the end of the discharge phase.

[0016] The total charge is represented by the area enclosed by the discharge curve and the discharge time axis. The relationship between battery power consumption in each discharge stage is established as S1 = S(f(t)). v1 S2=S(f(t)) v2 S3 = S(f(t) v3 The total charge E = S(f(t1)) + S(f(t2)) + S(f(t3)); where S(f(t1)) + S(f(t2)) + S(f(t3)) = S(f(t3)). v1 )), S(f(t) v2 )), S(f(t)v3 )) for f(t) v1 f(t) v2 f(t) v3 The corresponding area calculation formula is obtained by definite integral; S(f(t1)), S(f(t2)), and S(f(t3)) represent the total power consumption of each discharge stage.

[0017] Establish the formula for calculating the remaining charge C in the initial stage of discharge:

[0018] C = ES(f(t) v1 )), Vmin1≤V1≤Vmax1.

[0019] Establish the formula for calculating the remaining charge C during the stable discharge phase:

[0020] C = ES(f(t1)) - S(f(t) v2 )), Vmin2≤V2≤Vmax2.

[0021] Establish the formula for calculating the remaining charge C at the end of the discharge phase:

[0022] C = ES(f(t1)) - S(f(t2)) - S(f(t) v3 )), Vmin3≤V3≤Vmax3.

[0023] Furthermore, the battery power monitoring circuit includes an MCU and a power supply circuit, a sampling sub-circuit, and a temperature sensor module connected to the MCU; the sampling sub-circuit is also connected to the power supply circuit.

[0024] Furthermore, after the battery power monitoring circuit is powered on, the MCU records the battery discharge time in real time, obtains the current ambient temperature and current discharge voltage once in a cycle, and calculates the remaining power according to the calculation formula found in this cycle.

[0025] The present invention has the following beneficial effects:

[0026] This invention improves the accuracy of battery charge measurement in environments with fluctuating temperatures by querying discharge curves for different temperature ranges based on the current ambient temperature. It divides the discharge curve into three discharge stages and establishes calculation formulas for the remaining charge corresponding to each stage. By querying the calculation formula for the current discharge stage using the current discharge voltage, the remaining charge at different discharge stages can be calculated more accurately. Furthermore, the monitoring circuit uses a general sensor system circuit, enabling more accurate monitoring of the button battery's remaining charge without increasing system power consumption.

[0027] In addition to the objectives, features, and advantages described above, the present invention has other objectives, features, and advantages. The invention will now be described in further detail with reference to the accompanying drawings. Attached Figure Description

[0028] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0029] Figure 1 This is a flowchart of a button battery power monitoring method according to a preferred embodiment of the present invention;

[0030] Figure 2 This is a discharge curve of a certain brand of button battery at an ambient temperature of T=25°C, based on the actual power consumption of the wireless sensor system in a laboratory setting, according to a preferred embodiment of the present invention.

[0031] Figure 3 This is a circuit diagram of a battery power monitoring system according to a preferred embodiment of the present invention. Detailed Implementation

[0032] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings, but the present invention can be implemented in many different ways as defined and covered by the claims.

[0033] See Figure 1 In a preferred embodiment of the present invention, a method for monitoring the charge level of a button battery includes the following steps:

[0034] S1: Establish at least two non-overlapping temperature ranges and obtain the discharge curves of the button cell corresponding to each temperature range.

[0035] Furthermore, since temperature fluctuations within a small range have little impact on battery capacity and discharge, a discharge curve is typically measured every 2.5 degrees Celsius, meaning a temperature range T is defined as 5 degrees Celsius. The discharge curve for each temperature range T represents the discharge curve at the center temperature of that range. See also... Figure 2 This refers to the discharge curve of a certain brand of button battery, measured in the laboratory at an ambient temperature T = 25 degrees Celsius. Specifically, it shows the change in discharge voltage V as discharge time t increases within the temperature range of 22.5-27.5 degrees Celsius. By obtaining discharge curves from different temperature ranges, it is possible to eliminate the possibility that temperature variations could cause differences in the discharge curves, thus affecting the accuracy of calculating the remaining battery capacity.

[0036] S2: Divide each discharge curve into three discharge stages, and fit the calculation relationship between the remaining charge and discharge time corresponding to each discharge stage curve.

[0037] Furthermore, the discharge curves will vary depending on the battery brand, model, load, and ambient temperature. Generally, however, button cell batteries exhibit the highest discharge voltage at the beginning of discharge, followed by a rapid decrease. Once a certain voltage level is reached, the voltage stabilizes, and after a period of stabilization, it decreases again until it reaches the cutoff voltage. Therefore, by dividing the discharge curve into three stages based on the voltage-time variation, and establishing corresponding formulas for calculating remaining capacity based on the characteristics of each stage, the remaining capacity of the battery at each discharge stage can be calculated more accurately.

[0038] Figure 2 As shown, the t0-t1 discharge period is the curve of the initial stage of battery discharge, during which the discharge voltage decreases as the discharge time increases; the t1-t2 discharge period is the curve of the stable discharge stage of the battery, during which the discharge voltage tends to stabilize, and the discharge curve is parallel to the discharge time axis; the t2-t3 discharge period is the curve of the final stage of battery discharge, during which the discharge voltage decreases as the discharge time increases, eventually decreasing to the cutoff voltage, which is the minimum voltage value for normal system operation. That is, when the discharge time is t3, the button battery is depleted.

[0039] Furthermore, the following is based on Figure 2 The discharge curves in the medium temperature range of 22.5-27.5 degrees Celsius were used to establish the calculation relationship between the remaining charge C and the discharge time t for the three discharge stages. The process is as follows:

[0040] In the initial stage of battery discharge, the relationship between the discharge voltage t and the discharge time V, as well as the discharge voltage range and discharge time range, are established by using the method of undetermined coefficients or with the help of computer software:

[0041] V1=f(t v1 ), Vmin1≤V1≤Vmax1, t0≤t v1 ≤t1, where V1 is the discharge voltage during the initial stage of battery discharge; Vmin1 and Vmax1 are the minimum and maximum voltage values ​​during the initial stage of battery discharge, respectively.

[0042] In the initial stage of battery discharge, the battery power consumption S1 can be represented by the curve f(t). v1 The area enclosed by the discharge time coordinate axis (horizontal axis) is represented by:

[0043]

[0044] During the stable discharge phase of a battery, the relationship between the discharge voltage t and the discharge time V, as well as the discharge voltage range and discharge time range, are typically established using the undetermined coefficient method or computer software.

[0045] V2=f(t v2 Vmax1 <V2≤Vmax2,t1<t v2 ≤t2, where V2 is the discharge voltage during the stable discharge phase of the battery; Vmin2 and Vmax2 are the minimum and maximum voltage values ​​during the stable discharge phase of the battery, respectively.

[0046] During the stable discharge phase of the battery, the battery power consumption S2 can be represented by the curve f(t). v2 The area enclosed by the discharge time coordinate axis (horizontal axis) is represented by:

[0047]

[0048] In the final stage of battery discharge, the relationship between the discharge voltage t and the discharge time V, as well as the discharge voltage range and discharge time range, are established by using the method of undetermined coefficients or with the help of computer software:

[0049] V3=f(t v3 Vmax2 <V3≤Vmax3,t2<t v3 ≤t3, where V3 is the discharge voltage at the end of the battery discharge; Vmin3 and Vmax3 are the minimum and maximum voltage values ​​at the end of the battery discharge, respectively.

[0050] Then, at the end of the battery discharge, the battery power consumption S3 can be represented by the curve f(t). v3 The area enclosed by the discharge time coordinate axis (horizontal axis) is represented by:

[0051]

[0052] In summary, the area enclosed by the discharge curve and the discharge time axis within the temperature range of 22.5-27.5 degrees Celsius is represented as the total battery capacity E:

[0053] E=S1+S2+S3=S(f(t1))+S(f(t2))+S(f(t3)).

[0054] The formula for calculating the remaining capacity C is derived from the relationship between battery power consumption and total capacity during the initial discharge phase curve:

[0055] C = ES(f(t) v1 )), Vmin1≤V1≤Vmax1.

[0056] Based on the relationship that the discharge voltage tends to stabilize during the discharge stabilization phase, i.e., the curve of the discharge stabilization phase segment is approximately parallel to the coordinate system of discharge time t, the formula for calculating the remaining capacity C can be obtained by combining the ratio of the discharge time in the discharge stabilization phase to the total discharge stabilization phase time with the battery power consumption formula:

[0057] C = ES(f(t1)) - S(f(t) v2 Vmax1 <V2≤Vmax2。

[0058] The formula for calculating the remaining capacity C is derived from the relationship between the battery's power consumption and total capacity during the final discharge phase of the battery:

[0059] C = ES(f(t1)) - S(f(t2)) - S(f(t) v3 Vmax2 <V3≤Vmax3。

[0060] The above are the calculation formulas for the remaining charge C and discharge time t for the three discharge stages within the temperature range of 22.5-27.5 degrees Celsius. The calculation formulas for the remaining charge C and discharge time t for the three discharge stages within other temperature ranges T are also established using the above process. This calculation process establishes a mapping relationship between the physical quantity of battery charge and the mathematical quantity of plane area, making the battery charge more intuitive and visual. Finally, the calculation formulas for the remaining charge C and discharge time t for the three discharge stages within different temperature ranges T, along with the corresponding discharge voltage ranges for the three discharge stages, are stored in the non-volatile memory space of the system or the MCU itself.

[0061] S3: Construct a battery power monitoring circuit, query the discharge curve under the matching temperature range based on the current ambient temperature, then find the discharge stage of the current discharge voltage in the discharge curve, and then calculate the remaining battery power according to the calculation formula corresponding to the discharge stage.

[0062] Button batteries have a small capacity, typically between 40mAh and 150mAh, so they are generally used in small, low-power components. Therefore, even a slightly complex measurement circuit for a button battery can significantly impact its lifespan. Thus, this embodiment... Figure 3 This document presents a basic block diagram of a button battery power monitoring circuit based on a wireless sensor system. The monitoring circuit employs a basic sensor system circuit structure, requiring no additional external circuitry. The monitoring circuit includes: a button battery, a power supply circuit, a sampling sub-circuit, an MCU, a temperature sensor module, an RF sub-circuit, and an RF antenna.

[0063] The button battery is connected to the MCU via an electronic power supply circuit, which in turn supplies power to the entire monitoring circuit. One sampling sub-circuit connects the power supply circuit to the MCU to acquire the button battery's discharge voltage and transmit the sampling information to the MCU. The other sampling sub-circuit connects the temperature sensor module to the MCU to acquire the ambient temperature T0 measured by the temperature sensor module and transmit the sampling information to the MCU. The radio frequency (RF) sub-circuit connects the RF antenna to the MCU to transmit the button battery power information monitored by the MCU to the RF antenna.

[0064] After the button cell battery starts supplying power, the MCU records the battery discharge time in real time and periodically obtains the current ambient temperature and current discharge voltage (the period is set according to the actual situation). It then calculates the remaining battery power based on the formula looked up in this cycle. The process is as follows:

[0065] S4: The MCU records the battery discharge time t in real time after the button battery starts to supply power.

[0066] Furthermore, since the RF system of this type of button battery is usually in a continuously powered state, it will not be powered off and replaced with a new button battery until the button battery is low on power. That is, the MCU will not stop recording the battery discharge time t and reset the discharge time to 0 until a new button battery is replaced.

[0067] S5: At the end of a cycle, the MCU acquires the current ambient temperature T0 measured by the temperature sensor module and acquires the current battery discharge voltage V through the sampling sub-circuit.

[0068] S6: The MCU determines which set temperature range T the ambient temperature T0 is in, and queries the calculation relationship between the remaining charge C and the discharge time t for the three discharge stages under the temperature range T, as well as the discharge voltage range for the three discharge stages.

[0069] S7: The MCU determines the discharge voltage range of the three discharge stages in which the current discharge voltage V is located, determines the calculation formula of the discharge stage corresponding to the current discharge voltage range, and substitutes the current discharge time t into the formula to calculate the remaining charge C.

[0070] S8: The signal is transmitted to the receiver or host computer via radio frequency in the form of a percentage of the total power.

[0071] Furthermore, at the end of the battery discharge phase, the detection circuit can be set with a low battery alarm threshold according to the actual application. When the remaining battery power C reaches the alarm threshold, an alarm signal is issued to remind relevant personnel to replace the battery.

[0072] Furthermore, the aforementioned sampling sub-circuit includes an ADC sampling circuit and other methods for measuring battery discharge voltage; the aforementioned temperature sensor module includes a thermistor, or a temperature sensor integrated within the MCU, or a temperature sensor module composed of other integrated temperature sensor chips; for the monitored remaining battery power, methods including but not limited to sending radio frequency signals, or other methods that can display or send power can also be used instead.

[0073] In summary, this method, by measuring discharge curves under different ambient temperatures and introducing temperature as a variable, can effectively improve the accuracy of battery charge measurement under varying ambient temperature conditions. Furthermore, by subdividing the battery discharge process into three stages and using different calculation formulas to measure the remaining charge in each stage, the remaining charge can be obtained more accurately. In the stable discharge stage, where the discharge voltage is essentially constant, this method uses discharge time to calculate the charge, resulting in a more accurate and concise calculation of the remaining charge. Moreover, this method uses a standard sensor system circuit, achieving accurate measurement of the remaining battery charge without requiring additional external power or system power consumption.

[0074] The discharge curves of button batteries from different manufacturers and models, as well as under different load conditions, vary in the market. This solution expands the applicability of the battery power algorithm, making it suitable for button batteries from different manufacturers, models, and under different load conditions. By pre-storing and querying the calculation formulas for the remaining power of various button batteries, the remaining battery power is calculated, which greatly improves the effectiveness of battery power monitoring.

[0075] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for monitoring the charge level of a button battery, characterized in that, Includes the following steps: S1: Establish at least two non-overlapping temperature ranges and obtain the discharge curves of the button cell corresponding to each temperature range. S2: Divide each discharge curve into three discharge stages, and fit the calculation relationship between the remaining charge and discharge time corresponding to each discharge stage curve. The process of establishing the computational relation includes: Establish the calculation formulas for the discharge voltage V and discharge time t corresponding to the three discharge stages within the temperature range: Initial stage of discharge: V1 = f(t) v1 ), Vmin1≤V1≤Vmax1, t0≤t v1 ≤t1; where V1 is the discharge voltage during the initial stage of discharge, t v1 t0 is the discharge time in the initial stage of discharge; Vmin1 and Vmax1 are the minimum and maximum voltage values ​​in the initial stage of discharge, respectively; t0 is the start time; and t1 is the maximum discharge time in the initial stage of discharge. Stable discharge phase: V2=f(t) v2 ), Vmin2≤V2≤Vmax2, t1 <t v2 ≤t2; where V2 is the discharge voltage during the stable discharge phase, t v2 t2 represents the discharge time during the stable discharge phase; Vmin2 and Vmax2 represent the minimum and maximum voltage values ​​during the stable discharge phase, respectively; t2 represents the maximum discharge time during the stable discharge phase. Final stage of discharge: V3 = f(t) v3 ), Vmin3≤V3≤Vmax3, t2 <t v3 ≤t3; where V3 is the discharge voltage t at the end of the battery discharge process. v3 t3 represents the discharge time at the end of the discharge phase; Vmin3 and Vmax3 represent the minimum and maximum voltage values ​​at the end of the discharge phase, respectively; and t3 represents the maximum discharge time at the end of the discharge phase. The total charge is represented by the area enclosed by the discharge curve and the discharge time axis. The relationship between battery power consumption in each discharge stage is established as S1 = S(f(t)). v1 S2=S(f(t)) v2 S3 = S(f(t) v3 The total charge E = S(f(t1)) + S(f(t2)) + S(f(t3)); where S(f(t1)) + S(f(t2)) + S(f(t3)) = S(f(t3)). v1 )), S(f(t) v2 )), S(f(t) v3 )) for f(t) v1 f(t) v2 f(t) v3 The corresponding area calculation formula is obtained by definite integral; S(f(t1)), S(f(t2)), and S(f(t3)) represent the total power consumption of each discharge stage, respectively; Establish the formula for calculating the remaining charge C in the initial stage of discharge: C=E-S(f(t v1 )),Vmin1≤V1≤Vmax1; Establish the formula for calculating the remaining charge C during the stable discharge phase: C=ES(f(t1))-S(f(t v2 )), Vmin2≤V2≤Vmax2; Establish the formula for calculating the remaining charge C at the end of the discharge phase: C=E-S(f(t1))-S(f(t2))-S(f(t v3 )),Vmin3≤V3≤Vmax3; S3: Construct a battery power monitoring circuit, query the discharge curve under the matching temperature range based on the current ambient temperature, then find the discharge stage of the current discharge voltage in the discharge curve, and then calculate the remaining battery power based on the calculation formula corresponding to the discharge stage. The battery power monitoring circuit includes an MCU and a power supply circuit, a sampling sub-circuit, and a temperature sensor module connected to the MCU. The sampling sub-circuit is also connected to the power supply circuit. The button battery is connected to the MCU through the power supply circuit. One sampling sub-circuit is connected to the power supply circuit and the MCU to collect the discharge voltage of the button battery and transmit the sampling information to the MCU. The other sampling sub-circuit is connected to the temperature sensor module and the MCU to collect the ambient temperature measured by the temperature sensor module and transmit the sampled ambient temperature information to the MCU.

2. The button battery power monitoring method according to claim 1, characterized in that, The discharge curve is the discharge curve at the center temperature of each temperature range.

3. The button battery power monitoring method according to claim 1, characterized in that, The three discharge stages include: the initial discharge stage where the discharge voltage decreases monotonically with increasing discharge time, the final discharge stage, and the stable discharge stage where the discharge voltage remains constant.

4. The button battery power monitoring method according to claim 1, characterized in that, After the battery power monitoring circuit is powered on, the MCU records the battery discharge time in real time, obtains the current ambient temperature and current discharge voltage once in a cycle, and calculates the remaining power according to the calculation formula found in this cycle.

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