A method for testing the maintenance effect of lead-acid batteries

Abstract

The present invention discloses a method for testing the maintenance effect of a lead-acid battery, including the step of rapid sulfation of the lead-acid battery: by using the method of alternately changing the ambient temperature to impact, the speed of recrystallization of lead sulfate on the plate surface can be accelerated. Through the method of the present invention, the active substances on the plate surface of the lead-acid battery can quickly crystallize, causing rapid sulfation of the plates, so that the detection of the maintenance effect of the battery can be carried out in a short period, and both the detection result can be obtained quickly and the result can be relatively accurate.

Description

Technical Field

[0001] The present invention relates to the technical field of lead - acid battery maintenance, and particularly to a method for testing the maintenance effect of lead - acid batteries. Background Art

[0002] The main reason for the sulfation failure of lead - acid batteries is the sulfation crystallization of the active substances on the battery plates, resulting in the formation of large PbSO4 crystals, which leads to the failure of the active substances. In view of this situation, in order to extend the service life of the battery, various methods have been adopted in the prior art to modify the negative plates of lead - acid batteries. However, although the above - mentioned repair technologies can repair sulfated lead - acid batteries to a certain extent, they all have certain defects. Therefore, new lead - acid battery maintenance methods have been designed to effectively prevent lead - acid batteries from sulfating.

[0003] However, the general service life of lead - acid batteries is 2 to 3 years. Since the active substances on the surface of the plates of new lead - acid batteries do not recrystallize during the initial use period, the sulfation of the plates accumulates gradually during the use of the battery. Therefore, if the batteries using the new maintenance method are tested, the cycle for testing the maintenance effect is relatively long. It takes several months or even longer for the battery to be cycled to have a relatively obvious effect. At the same time, it is very difficult to exclude the influence of other factors during the test due to the too - long test cycle. Summary of the Invention

[0004] The purpose of the present application is to provide a method for testing the maintenance effect of lead - acid batteries, so as to enable the plates to sulfonate quickly, thereby enabling the batteries using the new maintenance method to be tested in a relatively short time.

[0005] To achieve the purpose of the present invention, the following solution is provided: A method for testing the maintenance effect of lead - acid batteries includes the step of quickly sulfating the lead - acid battery: By using the method of alternately changing the ambient temperature to impact, the speed of the recrystallization of lead sulfate on the plate surface can be accelerated.

[0006] Among them, the use of alternately changing the ambient temperature means cyclic impact through two environments with a large temperature difference.

[0007] Among them, the cyclic impact through two environments with a large temperature difference means being placed in environments of 40°C and - 20°C respectively for a long - time static state according to a certain test method.

[0008] Among them,

[0009] Specifically: Under the condition of 25°C ± 2°C, charge the battery with a current of 10 A for 3 hours, then place the battery in a high-temperature box at a temperature of 40°C for 12 hours to make the internal temperature of the battery reach 40°C. Adjust the battery test system to discharge the battery with a current of 3 A until the voltage reaches the cut-off voltage of 10.50 V ± 0.05 V, place it at room temperature for 12 hours, then charge the battery with a current of 10 A for 3 hours, and then place the battery in a low-temperature device at a temperature of -20°C for 12 hours to make the battery temperature reach -20°C. Adjust the battery test system to discharge the battery with a current of 3 A until the voltage reaches the cut-off voltage of 10.50 V ± 0.05 V. Take this as one cycle. After 30 times of each cycle, conduct an inspection on the battery life of the battery plates.

[0010] Among them, the observation method is used to detect the service life of the battery.

[0011] Among them, an X-ray powder diffractometer is used to measure the lattice parameters and conduct qualitative and quantitative phase analysis. The test uses the method of quantitative analysis without standard samples to conduct quantitative analysis on substances and determine the substance content.

[0012] Among them, to ensure the accuracy of the test results, the method of collecting the powder of the battery plates at multiple points is adopted - collect the powder at three places at both ends and the midpoint of the diagonal of the battery plates for observation, and record them as the powder images at the positions of battery plates 1# to 3# respectively.

[0013] Among them, after obtaining the images, the MDI jade6.5 software is used to analyze the images. When processing the images, it is necessary to fit the peaks of the substances with the standard library, and then divide the peak area of the substances by the total area of the curve to obtain the content of the substances. Through the comparison and research of the test results on different battery plates, quantitative analysis is carried out.

[0014] Among them, for the convenience of test observation, the battery plates adopt movable battery plates so as to be able to take them out at any time to sample the powder of the battery plates.

[0015] Compared with the prior art, the beneficial effect of the present invention is that through the method of the present invention, the active substances on the surface of the lead-acid battery plates can quickly crystallize, causing the battery plates to quickly sulfonate, so that the detection of the battery maintenance effect can be carried out in a short period, and both the detection result can be obtained quickly and the result can be relatively accurate. Brief Description of the Drawings

[0016] Figure 1 The following shows the schematic flow chart of the method steps of the present application;

[0017] Figure 2 The following shows the schematic structure diagram of the maintenance device of the present application;

[0018] Figure 3The circuit schematic diagram of the main circuit of the maintenance device of the present application is shown;

[0019] Figure 4 The equivalent circuit schematic diagram of the main circuit when the maintenance device of the present application is connected to both ends of the battery is shown;

[0020] Figure 5 The equivalent circuit schematic diagram when the MOS tube of the maintenance device of the present application is conducting is shown;

[0021] Figure 6 The equivalent circuit schematic diagram when the MOS tube of the maintenance device of the present application is turned off is shown;

[0022] Figure 7 The pin diagram of the ATtiny24 single-chip microcomputer of the present application is shown;

[0023] Figure 8 The peripheral circuit diagram for the basic operation of the ATtiny24 single-chip microcomputer of the present application is shown;

[0024] Figure 9 The circuit principle diagram of the power supply voltage conversion circuit of the maintenance device of the present application is shown as follows;

[0025] Figure 10 The drive circuit schematic diagram of the MOS tube of the maintenance device of the present application is shown;

[0026] Figure 11 The system control flow chart of the maintenance device of the present application is shown;

[0027] Figure 12 The structural schematic diagram of the maintenance device of the present application externally placed on the upper end cover of the battery is shown. Detailed implementation manners

[0028] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0029] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments may be combined with each other.

[0030] Embodiment

[0031] In this embodiment, a self-maintenance method for lead-acid batteries applies charge and discharge pulses with a certain frequency to the battery. These charge and discharge pulses keep the active substances inside the battery in an activated state all the time, can break the conditions for the formation of PbSO4 crystals, prevent the lead-acid battery from sulfation failure, and extend the service life of the battery.

[0032] Principle of self-maintenance of lead-acid batteries: Sulfide ions have five different energy levels. Ions in the metastable energy level tend to migrate to the stable covalent bond energy level and exist there. Sulfur in the stable covalent bond energy level exists in the form of a ring molecule containing 8 atoms. This ring molecule pattern of 8 atoms is a relatively stable combination, difficult to jump and be broken. Sulfur atoms in PbSO4 crystals are in this stable energy level state. To break the structure of these sulfide layers, a certain amount of energy needs to be provided to the ring molecule to activate the electrons carried by the outer atoms to the next higher energy band, so that the atoms are released from the bondage. Since each specific energy level has a unique resonance frequency, energy outside the resonance frequency that is too high will make the jumping atoms in an unstable state, and too low energy is not enough to make the atoms break away from the bondage of the atomic group. In this way, the pulse maintenance device generates pulses of a certain frequency, which resonate with sulfur atoms, enabling sulfur atoms to be converted into free ions dissolved in the electrolyte, re-participate in the electrochemical reaction, and be re-converted into active substances, thus realizing the self-maintenance of lead-acid batteries.

[0033] 1. Experimental studies have shown that after installing a maintenance device on a lead-acid battery, its service life is significantly extended compared to ordinary lead-acid batteries;

[0034] 2. Through the simulation study of the circuit design of the battery maintenance device, the battery structure design, and the feasibility test study, it is shown that the technical route for the development of self-maintaining lead-acid batteries is feasible.

[0035] Specifically, the battery maintenance device is used to perform self-maintenance on the battery.

[0036] 1. Overall battery structure design

[0037] The battery maintenance device is a circuit system. The strong acid environment inside the lead-acid battery corrodes the circuit system very seriously. At the same time, in order not to affect the normal use of the battery, the size of the battery cannot be increased too much. Therefore, for the structural design of the upper end cover of the automatic maintenance type lead-acid battery, an installation space needs to be arranged on the upper end cover of the battery for the maintenance device. Figure 12 Schematic diagram of the maintenance device arranged outside the battery.

[0038] When the maintenance device is arranged outside the battery, the requirement for the acid-proof liquid corrosion function of the maintenance device is relatively low. And when it is close to the terminal post, it is easy to realize the connection between the maintenance device and the terminal post. And by customizing the housing of the maintenance device, integrating it with the battery housing has the functions of dust-proof and waterproof, and can withstand a certain degree of mechanical shock.

[0039] To realize the integration of the battery maintenance device and the battery, the maintenance device needs to be reliably fixed on the battery housing. Through in-depth research on the battery production and processing technology, it is determined that the epoxy resin glue and heat sealing method bonding method will be adopted.

[0040] Epoxy resin glue is the adhesive used for sealing the end cover and the housing of lead-acid batteries. It is prepared from epoxy resin and an accelerator (or curing agent) and hardens in about half an hour. It has the properties of sealing, preventing acid liquid corrosion, and withstanding a certain degree of mechanical impact. Therefore, epoxy resin glue can be used to fix the maintenance device to the battery end cover. At the same time, heat sealing can also be used for bonding. For the battery case and the housing of the maintenance device made of polypropylene or polyethylene materials, heat sealing can be adopted, that is, heating with a controllable electric heater to exactly the plastic softening temperature, then pressing the two together and cooling them to achieve the purpose of installation and fixation.

[0041] When connecting the lead-out wire of the maintenance device to the pole column, a wire groove can be reserved in the mold of the device housing for laying the wire. When connecting the wire to the pole column, a through hole with a smaller diameter can be drilled on the pole column, and the wire is introduced and then welded firmly with lead. Then, marking paint is injected at the connection part between the pole column and the wire for sealing. The wire groove is lower than the upper end cover plane of the battery. After sealing, the wires of the maintenance device are completely inside the housing of the maintenance device, providing effective protection.

[0042] In addition, the current collector is one of the important components of lead-acid batteries. At present, the grid of the lead-acid battery plate still based on lead-calcium alloy, and element bismuth can be added for strengthening.

[0043] In addition, lead-acid batteries have always suffered from the passivation of the electrode surface caused by the sulfation of the plates, which seriously affects the discharge capacity and cycle life of the battery during high-current discharge. Selecting appropriate electrolyte additives can improve the high-current discharge capacity and cycle life. On the one hand, it is to meet the requirements of improving the electrochemical performance of the battery; on the other hand, it is also to meet the market application needs of vehicles such as scooters.

[0044] The active substances of lead-acid batteries include the active substances of the positive and negative plates and the active substances of the electrolyte. For different active substances and different functions, there are different additives. After demonstration and research, the additives suitable for military lead-acid batteries are mainly: for the positive plate: graphite, SnO, Bi2O3, and RSO3H; for the negative plate: lignin, humic acid, lignin cellulose, and BaSO4; for the electrolyte: alkali metals and NH 4+ .

[0045] In view of the above, a rapid sulfation test method for lead-acid batteries is adopted. This method proposes to use the environmental temperature alternating change impact method to shorten the test cycle. According to the crystal crystallization law, it is known that if the temperature changes during the recrystallization process of crystals, the crystallization will be accelerated. The battery pack using the self-maintenance method of lead-acid batteries is placed in environments of 40°C and -20°C respectively for a long time of static placement according to a certain test method. Through the cyclic impact of two environments with a large temperature difference, the speed of the recrystallization of lead sulfate on the plate surface can be accelerated.

[0046] The specific principle is as follows: Frequently performing small-current deep discharge on the storage battery will cause more lead sulfate to be generated deep in the electrode plates and agglomerate and adhere to the depths of the micropores of the active material, so that normal charging is not easy to fully act on the inner layer of the plate to restore it. At the same time, the alternating change of the ambient temperature will cause the two opposite processes of dissolution and crystallization of lead sulfate in the electrolyte to alternate, promoting and facilitating the formation of large-grained lead sulfate. When the temperature is too high, the lead sulfate crystals will form deeply and cannot be restored, accelerating the recrystallization process of the crystals. The specific method of small-current deep discharge is: Under the condition of 25°C ± 2°C, charge the storage battery with a current of 10A for 3 hours, then place the storage battery in a high-temperature box at a temperature of 40°C and place it for 12 hours to make the internal temperature of the storage battery reach 40°C. Adjust the storage battery test system to discharge the storage battery with a current of 3A until the voltage reaches the cut-off voltage of 10.50V ± 0.05V, place it at room temperature for 12 hours, then charge the storage battery with a current of 10A for 3 hours, and then place the storage battery in a low-temperature device at a temperature of -20°C and place it for 12 hours to make the temperature of the storage battery reach -20°C. Adjust the storage battery test system to discharge the storage battery with a current of 3A until the voltage reaches the cut-off voltage of 10.50V ± 0.05V, and use this as a cycle. After every 30 cycles, observe the electrode plates of the storage battery.

[0047] In order to eliminate the influence of environmental changes on the results of the self-maintenance verification test, while putting multiple groups of storage batteries into the same environment for testing, the formulated test rules are shown in Table 1 below.

[0048]

[0049] Table 1

[0050] In the test, in order to achieve ideal results, the following technical measures were taken:

[0051] (1) When the device gives a low-voltage alarm, charge the storage battery in time, and the ambient temperature of the storage battery cannot change during the charging process;

[0052] (2) Supplement distilled water to the electrolyte of the storage battery in time, especially in an environment with a temperature of 40°C, and the inspection and supplementation frequency should be appropriately increased;

[0053] (3) Regularly remove the frost in the refrigerator to avoid causing a short circuit of the storage battery during the test.

[0054] The service life of the automatic maintenance lead-acid storage battery and the ordinary lead-acid storage battery can be tested by the traditional method of directly detecting the capacity. However, this method has a very long cycle and is easily affected by other factors during the test process.

[0055] Therefore, in this embodiment, the observation method is used to detect the service life of the battery. The observation method indirectly characterizes the maintenance effect by observing the crystals after crystallization with the help of instruments and equipment.

[0056] The method of using an X-ray powder diffractometer to measure the lattice parameters and conduct qualitative and quantitative phase analysis of substances is adopted. The test uses the method of quantitative analysis without standard samples to analyze substances quantitatively and determine the content of substances. To ensure the accuracy of the test results, the method of collecting the powder of the battery plate at multiple points is adopted - collecting the powder at both ends and the midpoint of the diagonal of the plate for observation, and recording them as the powder images at the positions of the 1# to 3# battery plates of the battery respectively.

[0057] After obtaining the images, the MDI jade6.5 software is used to analyze the images, mainly using the functions of background subtraction, peak area calculation and curve smoothing of the software. When processing the images, it is necessary to fit the peaks of substances with the standard library, and then divide the peak area of the substance by the total area of the curve to obtain the content of the substance. Through the comparison and research of the test results on different battery plates, quantitative analysis is carried out.

[0058] For the convenience of test observation, the battery plates of the battery adopt movable plates so that they can be taken out at any time to sample the powder of the battery plates. For this reason, a test-use movable-plate type non-sealed lead-acid battery is made by oneself. The purchased battery adopts the assembly method of three positive plates and four negative plates. To make movable plates, the single cell of the self-made battery adopts the assembly method of two positive plates and three negative plates, and the upper cover is changed to a corrosion-resistant film to ensure the non-sealing of the battery and reduce the evaporation of the moisture in the electrolyte.

[0059] To determine the influence of the automatic maintenance type lead-acid battery on the battery plates, a comparative test between the automatic maintenance type lead-acid battery and the ordinary battery is carried out.

[0060] After 30 cycle tests, the plates of the two groups of batteries are taken out for observation. Through the diffraction test of the negative plates of the batteries at 10° to 90°, the powder comparison images at the positions of the 1# to 3# battery plates of the batteries are obtained.

[0061] The MDI jade6.5 software is used to analyze the test result curves. The diffraction peaks of the PbSO4 crystal phase are determined by using the peak height ratio, and its area is calculated. If the highest peak is affected by other elements, the second highest peak is selected and divided by the proportion of the diffraction secondary peak of the PbSO4 crystal phase in the PDF card library to be converted into the highest peak, and then its area is calculated, and then its content in the plate is calculated.

[0062] The parameter analysis of PbSO4 crystals in the automatic maintenance type lead-acid battery and the ordinary battery is shown in Table 2. From the data in Table 2, it can be obtained that the content of PbSO4 crystals in the battery embedded with the maintenance device is reduced by 44.46% after deep discharge with small current at high and low temperatures compared with that of the ordinary battery after deep discharge, effectively reducing the sulfation of the battery plates and showing obvious maintenance effect. When only considering the factor of sulfate formation on the battery plates, the service life of the battery embedded with the maintenance device can be effectively improved, indicating that the automatic maintenance type lead-acid battery has obvious advantages in preventing sulfate formation on the plates.

[0063]

[0064] Table 2

[0065] Corresponding to the above battery maintenance method, a battery maintenance device is provided.

[0066] As Figure 2 shown, the battery maintenance device includes a power supply module, a detection module, a signal indication module, a control module, a boost energy storage module and an electronic switch module.

[0067] This device is a self-powered device using the battery as the energy source. First, the battery voltage is sampled for judgment. When the voltage is normal, the battery voltage is boosted through boost conversion, and the boosted voltage is applied across the energy storage capacitor to charge the capacitor. After waiting for a certain time, the energy in the capacitor flows through the discharge circuit and is recharged into the battery, completing a charge-discharge pulse. The control module controls the MOS tube on the charge-discharge loop to adjust the frequency of the charge-discharge pulse. At the same time, by adjusting the resistance value of the potentiometer on the voltage feedback circuit of the boost energy storage module, the purpose of controlling the amplitude of the charge-discharge pulse can also be achieved. When the battery voltage is too low and the battery power is insufficient, the device can generate an audible and visual alarm to prompt the personnel to charge the battery in time.

[0068] Among them, the main circuit of the battery maintenance device uses the Boost topology circuit to achieve the boost function of the circuit, mainly by controlling the on and off of the MOS tube to control the frequency and amplitude of the charge-discharge pulse.

[0069] The switching MOS tube of the battery maintenance device is controlled by a pulse with a duty cycle of D, alternately conducting or turning off, so as to control the oscillation circuit composed of an inductor and a capacitor to complete the increase and decrease of the 12V voltage of the battery, form a charge-discharge pulse, and at the same time complete the charge-discharge process of the voltage pulse across the battery. The main circuit is as Figure 3 shown. Among them, the fuse GP60 mainly plays a role in protecting the circuit in case of short circuit and overcurrent; D2 is a fast recovery diode, mainly playing the function of preventing the reverse connection of the maintenance device; D3 is also a fast recovery diode, and its main function is to block the inductor L3 path when charging the capacitor.

[0070] The working process of the circuit is as follows:

[0071] When the maintenance device is connected to both ends of the battery, the MOS transistor is in the off state, and its equivalent circuit is as Figure 4 shown.

[0072] When the circuit starts to work, since the MOS transistor is in the normally-off state, L2 and C1 are connected to both ends of the battery. The battery charges C1 through L2. Due to the role of the inductor in suppressing current changes, at the moment when the circuit is turned on, the current passing through the inductor is still 0A. At this time, according to Kirchhoff's voltage law, since there is no charge stored across the capacitor, its voltage is 0V, and the voltage across the inductor is 12V, with the direction being positive on the left and negative on the right.

[0073] When the current in the circuit gradually increases, the capacitor stores the charge flowing through the inductor, and its voltage gradually rises, while the voltage across the inductor gradually decreases. When the voltage across the inductor drops to 0, the voltage across the capacitor is 12V. At this time, due to the effect of the inductor, the direction of the current does not change, and it continues to charge the capacitor. At the same time, the voltage across the inductor increases in the reverse direction, and the positive voltage across the capacitor also increases. When the current in the circuit drops to 0A, the voltage across the capacitor reaches the maximum value, and the voltage across the inductor reaches the maximum reverse value. At this time, since the voltage across the capacitor is greater than the voltage across the battery, the capacitor charges the battery. Similarly, due to the effect of the inductor, during the charging process, the voltage across the capacitor drops by more than 12V. When the current reverses again, it enters the next cycle. Further analysis of the steady-state process of the circuit reveals that after multiple cycles of oscillation, the voltage across the capacitor reaches 12V, and the current flowing through the inductor is 0A in the steady state. At this time, the battery is in the discharging state.

[0074] In the momentary conduction state of the MOS transistor, when the single-chip microcomputer detects that the battery voltage is equal to or higher than the program-set value, the single-chip microcomputer provides a square-wave pulse voltage to the MOS transistor drive circuit. When the MOS transistor is momentarily turned on, its equivalent circuit diagram is as Figure 5 shown. Since there are only inductors L2 and L3 on the main circuit of both ends of the battery, the conduction time of the MOS transistor must be short enough, otherwise it is equivalent to short-circuiting the battery.

[0075] At the moment when the MOS transistor is turned on, due to the effect of the inductor, an induced electromotive force with positive on the left and negative on the right will appear across the inductor. The induced electromotive force across the inductor will suppress the change in the flowing current. At the moment of instantaneous conduction, the currents flowing through L2 and L3 are zero, but the current will increase with time. At this time, the storage battery is in a discharging state. Under the hindering effect of the inductor, the current flows back to the storage battery through L2 and L3. At the same time, since the circuit forms a path, the charge stored in the capacitor C1 will also be released. However, the current direction at both ends of the inductor L2 will not change immediately, and according to the inductance values of L2 and L3, it can be judged that the rate of change of the current flowing through L3 is larger than that of the current flowing through L2. Therefore, the electric charge released by the capacitor C1 will flow back to the storage battery through the inductor L2, and the direction of the flowing current is as Figure 6 shown. During this stage, the storage battery is always in a discharging state, and its terminal voltage will drop to a certain extent, which will result in a discharging pulse of the storage battery.

[0076] When the MOS transistor is instantaneously turned off, the storage battery discharges for a certain period of time, and the MOS transistor drive circuit will provide a low-voltage pulse to turn off the MOS transistor. When the MOS transistor is turned off instantaneously, the loop of the main circuit changes, and its equivalent circuit diagram is as Figure 6 shown. Since the current flowing through both ends of the inductor will not change immediately, the current will still flow through L2 and back to the positive pole of the storage battery through the diode D1. To prevent the rapid disappearance of the current when the MOS transistor is turned off, a relatively high-value induction will be generated at both ends of the inductor L3.

[0077] The selection method of the key components in the above circuit is as follows:

[0078] 1) Selection calculation of inductors and capacitors

[0079] The boosting function of the maintenance device is mainly realized by the inductor in the Boost topology circuit, and then the high voltage is backfilled to both ends of the storage battery. The input voltage V IN of the main circuit is 12V, the boosted voltage V O is 22V, the duty cycle is 1 / 12, and the average charging current flowing through L2 is about 0.7A, that is, I O2 = 0.7A; the average charging current flowing through L3 is about 3.2A, that is, I O3 = 3.2A.

[0080] Therefore, the calculation of the inductor L2 is as follows:

[0081]

[0082] In the formula:

[0083] V O —The output voltage of the Boost topology circuit,

[0084] V IN— Input voltage of the Boost topology circuit,

[0085] D — Duty cycle,

[0086] I L2 — Current passing through inductor L2.

[0087] Taking the current ripple rate r as 0.6 and the oscillator frequency as 8.3 kHz, then:

[0088]

[0089] In the above formula, V ON is the voltage across the inductor during the conduction of the MOSFET. For the Boost topology circuit, V ON = V IN . Considering the losses, the parameters of inductor L2 are designed to be a rated current of 2 A and an inductance of 270 μH.

[0090] Similarly, inductor L3 can be calculated by the formula as follows:

[0091]

[0092] In the formula:

[0093] V O — Output voltage of the Boost topology circuit,

[0094] V IN — Input voltage of the Boost topology circuit,

[0095] D — Duty cycle,

[0096] I L3 — Current passing through inductor L3.

[0097] Taking the current ripple rate r as 0.6 and the oscillator frequency as 8.3 kHz, then:

[0098]

[0099] In the above formula,

[0100] V ON is the voltage across the inductor during the conduction of the MOSFET. For the Boost circuit, V ON = V IN . Considering the losses, the parameters of inductor L3 are designed to be a rated current of 4 A and an inductance of 60 μH. Capacitor C1 is used as a filter capacitor. Since the main circuit boosts the voltage to 22 V, in order to avoid the instantaneous back electromotive force from breaking down the capacitor, the parameters of capacitor C1 are designed to be a voltage rating of 35 V and a capacitance of standard 220 μF.

[0101] 2) MOS transistor type selection calculation

[0102] It is found in the research that the higher the frequency of the maintenance device, the better the maintenance effect on the lead-acid battery. By comprehensively analyzing the pulse frequencies of the existing lead-acid battery protector products, it is advisable to set the pulse frequency of the maintenance device at about 8 kHz. At the same time, since the pulse frequency of the protector is mainly affected by the switching frequency of the MOS tube, the switching frequency of the MOS tube should also be about 8 kHz. Since the turn-on voltage of the MOS tube is about 4.3 V, the maximum gate voltage of the selected power tube should be less than 4.3 V. The main circuit can boost the voltage up to 22 V. Considering that the flyback electromotive force generated by the inductor can reach 90 V, the breakdown voltage rating of the selected power switch tube should exceed 117 V. At the same time, considering that the current flowing through inductor L2 reaches 3.5 A instantaneously, the peak current of the selected power switch tube should exceed 4.6 A.

[0103] According to the above conditions and combined with the junction temperature and case temperature of the MOS tube, the model of the power switch tube selected for the main circuit design is IRF630. The turn-on voltage of this switch tube is 4 V, the breakdown voltage is 200 V, the drain-source on-resistance is 400 mΩ, and the pulse current that can be withstood under the condition of 25 °C reaches 9 A, with very low power consumption.

[0104] NI Multisim software is an EDA tool software specifically used for electronic circuit simulation and design. Use Multisim software to complete the construction of the simulation model of the main circuit of the maintenance device.

[0105] The control circuit of the battery maintenance device adopts a digital circuit.

[0106] The digital circuit scheme adopts microprocessor technology in terms of hardware and realizes the functions of the circuit through software program control. The hardware system of the designed device consists of modules such as a DC / DC module, a detection module, a signal indication module, a control module, a boost module, and a power MOSEFT electronic switch.

[0107] 1) Selection of the control chip and design of the control circuit

[0108] The control unit is used for the control of the battery online maintenance device. To meet the requirements of low power consumption and miniaturization in the overall design, the microcontroller selects the ATtiny24 single-chip microcomputer of Atmel Corporation. Its pin diagram is as Figure 7 shown. The peripheral circuit for the basic operation of the ATtiny24 single-chip microcomputer is as Figure 8 shown.

[0109] Pin 4 of the ATtiny24 microcontroller has a reset function. If a low value persists within the time of its minimum pulse width, a reset is generated. Pin 6 delivers a square wave of a certain frequency to the driving circuit of the MOS transistor, controlling the on and off time and frequency of the MOS transistor. Pin 12 is the voltage sampling pin. One end of it is connected after the main circuit fuse to sample the battery voltage, and then the value is provided to the ATtiny microcontroller. After program analysis within the chip, the light-emitting diodes are controlled through pins 10 and 11, and the buzzer is controlled through pin 2. That is, when the battery voltage is lower than 11.8V, the buzzer of the protector alarms, and the light-emitting diodes on pins 10 and 11 flash alternately. Pin 13 obtains a definite voltage through the precision voltage regulator chip 431. At the same time, C4 and C5 are connected in parallel to filter out the clutter, serving as the reference voltage for A / D conversion. Pin 14 is grounded, and pins 5, 8, and 9 are left unconnected. Pin 1 of the ATtiny24 microcontroller provides the operating voltage for the microcontroller. Since the voltage across the battery is 12V while the operating voltage of the microcontroller is 5V, a voltage regulator is needed to convert the voltage.

[0110] The principle of the power supply voltage conversion circuit of the maintenance device is as Figure 9 shown.

[0111] The 7805 chip is a three-terminal positive voltage regulator that can provide a fixed 5V output voltage. When the input voltage is 4V - 7V higher than the output voltage, the output voltage is relatively stable. The output current can reach 500mA, and it has overheat protection and short-circuit protection functions. The input terminal and ground of this chip are connected to the output terminal of the power supply module. The output terminal of the chip provides a 5V output voltage. And the input terminal is connected in parallel with capacitor C1, and the output terminal is connected in parallel with capacitor C2 to filter out the clutter on the line.

[0112] The principle of the MOS transistor driving circuit of the maintenance device is as Figure 10 shown.

[0113] The MOS transistor of the maintenance device is connected to pin 6 of the ATtiny24 microcontroller through the switch terminal, obtaining a square wave pulse of a certain frequency from pin 6, and limiting the current and filtering through R10 and C9. When the high level of the square wave appears at the common base of the PNP transistor Q1 and the NPN transistor Q2, Q2 conducts, and the control terminal of the MOS transistor is connected to the ground. At this time, a low level is provided to the MOS transistor. When the low level of the square wave appears at the common base of the two transistors, Q1 conducts, and the control terminal of the MOS transistor is connected to +5V. At this time, a high level of +5V is provided to the MOS transistor. Through the alternating conduction of Q1 and Q2, exactly a voltage pulse can be provided to the MOS transistor to control its on and off. Among them, the high level of the voltage pulse is 5V, and the low level is 0V.

[0114] The battery maintenance device uses the AVR ATtiny24 single-chip microcomputer as the control chip. Combined with the design of the peripheral circuit, it is written in C language to develop a software program that realizes the functions of the maintenance device.

[0115] 1) System control flow design

[0116] The system control flow of the maintenance device is as Figure 11 shown.

[0117] First, the program in the single-chip microcomputer is initialized, including assigning initial values to each register, setting the timer / counter and AD acquisition register to zero, selecting the interrupt control and enabling the interrupt function. After the initialization is completed, the overall program enters the while(1) loop. In the loop, the first step is to collect the terminal voltage across the battery and compare this value with the parameters set by the system. When the battery voltage is less than the program-set value of 11.5V, the program considers that the battery voltage is too low and is in a state of discharging or semi-discharging. The maintenance device turns on the buzzer and the flashing diode, and there is an alarm sound and the red and green lights flash alternately to warn the staff, prompting them to charge the battery pack. If this value is greater than or equal to the set parameter, it is considered that the battery voltage is normal, and the maintenance device enables the online maintenance function, turns on the indicator light and turns off the buzzer, indicating that the maintenance device is working properly. At this time, the single-chip microcomputer outputs a voltage square wave with a certain frequency to drive the MOS tube in the charge and discharge circuit. Then, the on and off of the MOS tube are used to control the voltage pulse frequency and amplitude formed by the charge and discharge circuit.

[0118] 2) Program writing

[0119] When the battery is in a static state, the terminal voltage of the battery is relatively stable and the change range is very small. However, when the battery is in use, the maintenance device is still connected in parallel across the battery and works. At this time, the terminal voltage will change with the charge and discharge of the battery, and when the current is very large, the change of the terminal voltage is very obvious. Once the maintenance device collects this changing voltage, it cannot reflect the true state of the battery, resulting in misjudgment by this module and false alarms. Therefore, a capacitor has been used for power supply filtering in the hardware circuit design, which can filter out certain noise. At the same time, a certain software filtering technology is adopted to improve the credibility of the sampling value. When writing the program, the limited average value filtering algorithm is adopted.

[0120] First, the device collects the voltage value at both ends of the battery. This value should be within a normal range of the battery voltage. If it exceeds this range, this value is invalid and discarded. If this value is within this range, this value is added to a certain variable. Then, wait for a certain time interval, sample again, still judge this value, accumulate it into the variable or discard it, and record the number of accumulations. After accumulating to a certain number of times, stop sampling, use the average value of this variable as the normal value of the battery terminal voltage at this time, and then judge and execute the program.

[0121] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A method for testing the maintenance effect of a lead-acid battery, characterized in that, Including the steps of rapid sulfation of lead-acid batteries: By using the method of alternately changing the ambient temperature for impact, the speed of lead sulfate recrystallization on the plate surface can be accelerated; Specifically: Under the condition of 25°C ± 2°C, charge the battery with a current of 10A for 3 hours, then place the battery in a high-temperature box at a temperature of 40°C for 12 hours to make the internal temperature of the battery reach 40°C. Adjust the battery test system to discharge the battery with a current of 3A until the voltage reaches the cut-off voltage of 10.50V ± 0.05V, place it at room temperature for 12 hours, then charge the battery with a current of 10A for 3 hours, and then place the battery in a low-temperature device at a temperature of -20°C for 12 hours to make the battery temperature reach -20°C. Adjust the battery test system to discharge the battery with a current of 3A until the voltage reaches the cut-off voltage of 10.50V ± 0.05V. Take this as one cycle. After 30 times of each cycle, conduct an inspection on the battery life of the battery plates; Adopt the method of using an X-ray powder diffractometer to measure the lattice parameters and conduct qualitative and quantitative phase analysis; The experiment adopts the method of quantitative analysis without standard samples to analyze the substance quantitatively and determine the substance content; To ensure the accuracy of the test results, adopt the method of collecting the powder of the battery plates at multiple points - collect the powder at three positions at both ends and the midpoint of the diagonal of the battery plate for observation, and record them as the powder images at the positions of battery plates 1# to 3#; 2. The method for testing the maintenance effect of a lead-acid battery according to claim 1, characterized in that, The so-called use of alternately changing the ambient temperature refers to cyclic impact through two environments with large temperature differences.

3. The method for testing the maintenance effect of a lead-acid battery according to claim 2, characterized in that, The so-called cyclic impact through two environments with large temperature differences refers to being placed in environments of 40°C and -20°C respectively for long-term static placement according to a certain test method.

4. The method for testing the maintenance effect of a lead-acid battery according to claim 1, characterized in that, Adopt the observation method to detect the service life of the battery.

5. The method for testing the maintenance effect of a lead-acid battery according to claim 1, characterized in that, After obtaining the images, use MDIjade6.5 software to analyze the images. When processing the images, it is necessary to fit the peaks of the substances with the standard library, and then divide the peak area of the substance by the total area of the curve to obtain the content of the substance. Through the comparison and research of the test results on different battery plates, quantitative analysis is carried out.

6. The method for testing the maintenance effect of a lead-acid battery according to claim 5, characterized in that, For the convenience of test observation, the battery plates adopt movable battery plates so that they can be taken out at any time to sample the powder of the battery plates.

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