KR19990028876A - Control and Termination of Battery Charging Process - Google Patents

Abstract

A method and apparatus for adjusting the battery charging process to charge the battery as quickly as possible while avoiding overheating or damaging the battery. The method applies a charging pulse C1 that provides an average charging current, applies a first depolarization pulse D1, waits for the first resting period DW1, and applies the voltage V1 at a predetermined point in time within the first resting period. Measure, apply a second depolarization pulse D2, wait for the second pause DW2, measure the voltage V2 at a predetermined time within the second pause, and measure the difference between the voltage V1 and the voltage V2. And then the average charging current is reduced if the difference is greater than the predetermined amount. The invention also provides a method of measuring whether a battery is at a low level in water.

Description

How to control and terminate the battery charging process

There are several methods for charging the battery and some methods for measuring the end of the battery charging process. These methods all have the same problem: the battery is overcharged. When the battery is overcharged, oxygen is produced at the anode. This oxygen is then consumed by the cathode and the battery is heated. The risk of some damage to the battery due to overcharging is a normal procedure for most charging technologies. To some extent, battery manufacturers take this into account and design batteries with extra negative material. However, overcharge inevitably consumes a negative electrode, and once excess material is consumed, subsequent overcharge will reduce the amount of negative electrode that can be used for charge storage, which in turn reduces the capacity of the battery.

In particular, a well documented effect of overcharging with direct current charging is the fact that the battery voltage is reduced. This reduction in battery voltage is often referred to as negative delta V or negative delta V. One method of measuring the state of charge is to detect the occurrence of negative delta V and terminate the charging process when this occurs. However, this method shortens battery life because negative delta V occurs when excessive amounts of oxygen are produced by the positive electrode and consumed by the negative electrode. As a result, this method raises the battery temperature and also increases the pressure inside the battery.

Another method of measuring the end of charge process has been used to charge the battery by forcing a pulse of current through the battery and applying a discharge pulse after each charge pulse. In this method, the charging process is terminated in response to the average discharge current during the discharge pulse or in response to the energy ratio removed by the discharge pulse compared to the energy provided to the battery during the preceding charge pulse. However, there is no close relationship between the discharge voltage value and the state of charge of the battery.

Another charging process termination method provides sampling of the battery terminal voltage between charge pulses at a set time after charging commences.

Another method provides battery voltage measurement during charging current application and battery voltage measurement during discharge current. Compare the two voltage measurements and terminate the charging process when a predetermined difference exists between these voltages. However, the predetermined difference should be selected according to the type of battery to be charged and the capacity of the battery to be charged. Moreover, this method does not accurately measure the state of charge of the battery and does not prevent the generation of oxygen with overcharge. This is because if the battery is charged at a fast charge rate, and then a long discharge pulse is present, the nickel-cadmium (NiCd) or nickel-metal-hydride (NiMH) battery is heated and the charge voltage is due to a change in battery temperature. This is because the amplitude of is changed. Thus, this method is not precise for charging large batteries with fast charging, because even minor mistakes in measuring battery condition can damage the battery. A more complex problem is that battery characteristics change during the charge cycle and vary from battery to battery.

Another charge cycle control method uses a "resistance-free voltage" readout. The no-load ("no resistance") terminal voltage of the battery is measured after the end of the charge pulse. This voltage is compared with a reference voltage to measure the charging current. The reference voltage may depend, for example, on changes in ambient temperature, internal temperature, internal pressure, charging current, or charging current value. However, the measurement of non-resistance voltage should occur when all cells in the battery are in equilibrium mode. If an equilibrium condition is not achieved, the voltage measurement of the open circuit voltage may thus be different over time from the end of the preceding charge pulse. Equilibration time depends on the charge current and the mass transfer capacity of the battery. The measurement accuracy of the resistivity voltage will depend on the concentration of the electrolyte in the battery and the age of the battery. The concentration of the electrolyte will change due to the porous structure of the plate surface, so the measurement of the open circuit voltage milliseconds after the end of the charge pulse will not give accurate results. Thus, the battery may be overheated or destroyed. Moreover, there are differences between batteries, between battery types, and differences in a single battery that occur during a charge cycle. Therefore, selection of a suitable reference voltage can be difficult or very time consuming.

Other methods of quickly charging the battery should also take into account the permanently changing parameters of the battery, such as internal resistance, polarization resistance, mass transfer conditions and temperature. Rapid charging systems typically use a tapering current to avoid overcharge and gas generation. U.S. Patent 5,307,000 describes the use of multiple discharge pulses between each charge pulse and provides a method of rapidly charging a battery with high discharge pulse current for a long time without limit voltage and heat generation per cell. Without a plurality of depolarization pulses, the voltage on the battery will rise very quickly, especially at the end of the charge pulse, due to the rapid increase in concentration of the electrolyte around the electrode.

The fast charging process should be based on reliable and accurate charging control and charging termination methods. Some conventional charging methods rely on temperature cutoff, or other methods are not suitable and / or uniform for all types of batteries, even when used for charging the same battery type (lead-acid, NiCd, NiMH). There are ways to make choices. Other conventional charging methods have relied on voltage cutoff. However, the fixed voltage threshold is unreliable because the proper voltage threshold changes depending on the condition, temperature of the battery, pre-use of the battery and charging history.

As is known in the art, the preferred technique for rapid battery charging involves the process of forcing a high charge current into the battery, preferably by applying a series of charge and depolarization pulses to the battery. As the charging process becomes faster and the instantaneous charging current is higher, it becomes more difficult to determine when the battery is fully charged and the optimal time for termination or change of the charging process occurs. Without knowing exactly when the battery is fully charged, both charging time and energy are wasted due to overcharging of the battery.

However, as mentioned above, overcharging causes gas generation, generates heat, and increases pressure in the battery, thereby causing damage to the battery or potentially initiating a catastrophic thermal runaway condition in the battery. It is known that the battery is charged when the charging current stabilizes or begins to increase after a gradual decrease during the constant voltage charge mode. However, this method relies on changes in the terminal characteristics of the battery that occur when the battery is in a thermal runaway state. Therefore, it is desirable to measure whether the battery is charged without approaching the rush into the thermal runaway state.

Reduce charging current, prolong charging time, or prematurely fast charge based on some selected criteria, such as the amount of time the charging process has been applied, ampere-hour of charge forced into the battery, or battery temperature. By terminating, problems of gas generation, heating, thermal runaway, and other damage to the battery can be avoided. However, these methods can terminate the charging process prematurely, thereby allowing the battery to remain in a less charged state or significantly extending the time required for subsequent methods such as trickle charging to fully charge the battery. do. In addition, because the battery cannot tolerate high charge pulse currents, the use of the time of charge or amper-hour as a measure when the fast charging process is applied to the battery will result in catastrophic failure for a fully charged or nearly fully charged battery. Will be. In this case, gas generation and excessive heating of the battery will begin to occur almost immediately.

Therefore, the fast charging process can be used as long as possible, thus bringing the battery to a full or near full charge state, but charging the battery, especially during the fast charging process, to terminate the fast charging process before the battery is damaged. You need a way to accurately measure the condition.

In addition, during the fast charging process, at some point during which the battery is substantially charged, the battery may not be able to accept full current from the charge pulse. Thus, some of the charging current delivered during the charging pulse results in gas generation and heating. However, the termination of the fast charge process at this point is premature because the battery is not fully charged and there is still room for a fast charge process even at lower charge currents. Accordingly, there is a need for a method of modifying the fast charging process to continue rapid charging of the battery in an efficient manner as the battery is charged.

Accordingly, there is a need for a method of modifying the fast charging process to continue rapid charging of the battery in an efficient manner as the battery is charged.

Summary of the Invention

The present invention relates to a method for accurately measuring the battery charging time. In this way, the fast charging process is used for as long as possible, so that the battery is substantially charged, but the fast charging process is terminated at the time of avoiding overcharging of the battery and thus avoiding charging time and energy waste and battery damage.

In the present invention, in order to measure the battery charging timing, a charging pulse is applied to the battery followed by at least two discharge (depolarization) pulses. The battery voltage is measured at a predetermined time in the resting (standby) phase after the first depolarization pulse and at the same relative time in the resting period after the second depolarization pulse. Depolarization pulses are generated by loading across a battery terminal and are typically significantly shorter in duration than charging pulses.

When a charge pulse is applied to a lead-acid battery, lead sulfate in the battery solution is converted to lead, lead oxide, and electrolyte ions. Lead and lead oxide are deposited on each electrode. Electrolyte ions are formed on the electrode and surround the electrode. These electrolyte ions are dispersed by the transport phenomenon due to the difference in the ion concentration around the electrode and the ion concentration in the solution.

When the battery is rarely charged, the concentration to be concentrated is low, so that the electrolyte ions formed around the electrode rapidly disperse into the solution. However, when the battery is almost charged, the concentration difference is small and thus ions are dispersed more slowly. Lead ions cannot move near the electrode until the ions are dispersed. Thus, ions form a barrier around the electrode and prevent the electrode from efficiently receiving the other charge pulse. Moreover, a smaller amount of solution can be converted by the filling process. Once this occurs, the charge voltage must be increased to allow the battery to accept the same amount of charge current. However, an increase in charge voltage results in the dissociation of water in the battery into hydrogen gas and oxygen gas. Oxygen gas is quickly reabsorbed into the solution. However, hydrogen gas is absorbed very slowly and thus the pressure inside the battery is increased. In the event of a leak, hydrogen gas is lost, which causes the battery to lose water. If this happens too often, the battery will be dead. In addition, the high voltages required to charge the battery can result in unwanted heating of the battery and excessive heating can render the battery unusable.

The present invention describes that the state of charge of the battery, ie the electrolyte concentration in solution, can be measured by measuring the open circuit voltage of the battery during the rest period following the discharge pulse. If the open circuit voltage is approximately equal from one rest period to the next rest period, the battery is not overcharged and therefore the charging current does not need to be changed. If the open circuit voltage decreases from one pause to the next, the battery is overcharged or charged at a higher rate than the battery can accept and therefore must reduce the charging current or terminate the charging process.

Therefore, when the battery begins to charge, the charging current must be reduced to a level that the battery will accept efficiently.

In the present invention, the battery is measured to allow charging efficiently and the charging current need not change as long as the second voltage measurement is approximately equal to the first voltage measurement.

In addition, in the present invention, the battery is measured to be almost charged and the charging current should be reduced when the second voltage measurement is smaller by the predicted voltage difference ΔV than the first voltage measurement.

Accordingly, the present invention provides a method of accurately measuring the state of charge of a battery in a fast charging process and controlling or terminating the charging process to avoid battery damage.

It is therefore an object of the present invention to provide a method for measuring the state of charge of a battery more accurately by comparing battery voltages between different idle periods.

The present invention provides a battery charging method. This method applies a charge pulse that provides an average charge current, applies a first depolarization pulse, waits for a first rest period, measures the voltage of the battery at a predetermined time within the first rest period, and applies a second depolarization pulse. And waiting for a second pause, measuring a voltage of the battery at a predetermined time in the second pause, measuring a difference between the voltage at a predetermined time in the first pause and a predetermined time in the second pause, and then Varying the average charging current according to the amount and polarity of the difference.

As an aspect of the present invention, when the difference is within the prescribed range, application of a charging pulse, application of the first and second depolarization pulses, waiting of the first and second resting phases, and measurement of voltage at the first and second resting phases are performed. Repeat.

In another aspect of the invention, the charge pulse has a predetermined charge pulse duration and the average charge current change step includes a change in charge pulse duration.

In another aspect of the present invention, the charging pulse has a predetermined charging pulse current amplitude and the step of changing the average charging current includes changing the charging pulse current amplitude.

As yet another aspect of the present invention, the charge pulse has a predetermined charge pulse repetition rate and the step of changing the average charge current includes a change in the wind power pulse repetition rate.

As a further aspect of the present invention, each depolarized pulse has a predetermined depolarized pulse current amplitude and the method further comprises changing the depolarized pulse current amplitude when the average charging current is changed.

In another further aspect of the invention, each depolarized pulse has a predetermined depolarized pulse duration and the method further comprises changing the depolarized pulse duration when the average charging current is changed.

In another aspect of the present invention, a plurality of depolarized pulses follow each charge pulse and the method further includes changing the number of depolarized pulses when the average charge pulse changes.

The present invention also provides a battery charging method by a pulse charging process. The method applies a charge pulse, applies a first depolarized pulse, waits for a first rest period, measures the voltage of the battery at a predetermined point in the first rest period, applies a second depolarized pulse, and waits for a second rest period. Measure the voltage of the battery at a predetermined time in the second pause, measure the difference between the voltage at the scheduled time in the first pause and the predetermined time in the second pause, and then pulse if the difference is greater than the predetermined threshold. Terminating the filling process.

The present invention also provides a method of measuring battery status. The method applies a charging pulse to the battery, applies a first depolarization pulse to the battery, waits for a first rest period, measures the voltage of the battery at a first predetermined time point in the first rest period, and measures a second predetermined time in the first rest period. The battery voltage is measured at the time point, the second depolarization pulse is applied to the battery, the second pause is waited, the difference between the voltage at the first predetermined time point and the voltage at the second predetermined time point is measured, and then the difference is scheduled. If greater than the threshold, indicating that water should be added to the battery.

The present invention also provides a method for terminating a battery charging process. The method applies a charging pulse to the battery, applies a first depolarization pulse to the battery, waits for a first rest period, measures the voltage of the battery at a first predetermined time point in the first rest period, and measures a second predetermined time in the first rest period. Measuring the voltage of the battery at a time point, applying a second depolarization pulse to the battery, waiting for a second rest period, measuring a voltage of the battery at a first predetermined time point in the second resting time, and a second predetermined time point in the second resting time Measures a voltage of the battery, measures a second difference between the voltage at the first predetermined time point in the first resting period and the voltage at the second predetermined time point in the first resting time, and the voltage at the first predetermined time point in the second resting time. And measuring a first difference between the voltage at the second scheduled time in the second idle time and then terminating the charging process if the first difference is greater than the predetermined threshold and the second difference is greater than the predetermined threshold. do.

Other objects, features and advantages of the present invention will become apparent upon reading the following description of the preferred embodiments, taken in conjunction with the accompanying drawings and claims.

The present invention relates to a battery charger, in particular to a method and apparatus for controlling and charging a battery charging process.

1 is a block diagram of a battery charging circuit used in the present invention.

2A-2B are waveform diagrams illustrating how the state of charge of a battery is measured by comparing the battery charging process and voltage measurements taken at different rest periods.

3 is a flowchart illustrating a process of measuring a battery charge state.

4 is a waveform diagram illustrating a battery charging process and how the state of the battery is measured.

5 is a modified view of the flowchart of FIG. 3 illustrating a method of measuring a battery condition.

1 is a block diagram of a battery charging circuit used in the present invention. The battery charging and discharging circuit 10 includes a keypad 12, a controller 13, a display 14, a charging circuit 15, a discharge (depolarization) circuit 16, and a current monitor circuit 20. The keypad 12 is connected to the input “K” of the controller 13 and allows the user to specify regulatory parameters such as battery type (lead acid, NiCd, NiMH, etc.) and other corresponding values such as the battery nominal voltage or the number of cells in the series. Ask for information. Keypad 12 may be a keyboard, dial pad, switch arrangement, or other device for entering information. In order to simplify the operation by the user, the controller 13 can be pre-programmed with parameters for multiple battery types. In this case, the user will simply enter a battery type, such as a model number, and the controller 13 will automatically use the parameters appropriate for that battery type. Delay 14 is connected to the output " S " of controller 13 and displays information, selections, parameters, etc. for the operator and provides an audible and visible alarm or alerts the operator.

The output portion "C" of the controller 13 is connected to the charging circuit 15. The charging circuit 15 provides a charging current for the battery 11. Depending on the application, the charging circuit 15 can be modeled by the controller 13 to be performed as a constant voltage source or as a constant current source. The output " D " of the controller 13 is connected to a discharge (depolarization) circuit 16 which can be modeled by the controller 13 to provide a constant depolarization current to the battery 11. Apply a load or apply a lower or reverse voltage to the battery 11. The pulse width of the pulses provided by the circuits 15 and 16 is controlled by the controller 13. The outputs of the charging circuit 15 and the discharge circuit 16 are connected to the positive terminal of the battery 11 via the conductor 21. The negative terminal of the battery 11 is connected to the circuit ground through the current monitor resistor 20. Thus, the current flowing into or out of battery 11 can be determined by measuring the voltage across current monitor resistor 20 on conductor 22. Thus, the current monitor resistor 20 acts as a current monitor and current limiter. Of course, other devices may be used to measure battery current.

The battery voltage is monitored by measuring the voltage between conductor 21 and circuit ground. The influence of the current monitor resistor can be removed by measuring the voltage between the conductors 21 and 22, or by subtracting the voltage on the conductor 22 from the voltage on the conductor 21. The conductors 21 and 22 are connected to the inputs "V" and "T" of the controller 13, respectively.

The presence or absence of a battery operates the charging circuit 15 and monitors the output of the current monitor resistor 20 to measure whether the charging current flows, the operating the discharge circuit 16 and the output of the current monitor resistor 20. It can be measured by monitoring whether or not the charging current flows, and by monitoring the voltage with both circuits 15 and 16 which are inactive and measuring whether or not the battery is present.

The temperature sensor 23 monitors the temperature of the battery 11 so that the controller 13 can adjust the amplitude, number and duration of charge pulses and depolarization pulses and duration of rest periods to maintain the desired battery temperature. Although only one is shown in the figure, the temperature sensor 23 is preferably immersed in the electrolyte solution of each battery to accurately report the battery internal temperature. The temperature sensor 23 may be a thermostat, thermistor, thermocouple, or the like, and is connected to the input “T” of the controller 13.

The controller 13 includes a microprocessor, a memory at least part of which contains operating instructions for the controller 13, a timer, and an analog-to-digital converter. Using a microprocessor-based controller is advantageous because it allows the microprocessor to make very fast decisions, store voltage and current measurement data, and perform calculations on data such as averaging, comparing, and peak detection. Because there is. The timer, which may be isolated or provided by a microprocessor, may be used to provide control of the duration of charge pulses, depolarization pulses, or pauses, and to provide a time reference between successive depolarization pulses or pauses. Analog-to-digital converters, which may be separate or provided by a microprocessor, may be used to convert a voltage or current signal into a form that may be used by the digital microprocessor. Although a digital controller is discussed because it is a preferred aspect, analog controllers may be used in the practice of the present invention.

2A and 2B are waveforms illustrating the battery charging process and how the battery is charged. The state of charge is measured by comparing voltage measurements taken at different resting periods. The voltage and current waveforms are generally one or more charge pulses C1 (preferably followed by resting phase CW1) and a plurality of depolarized pulses D1-D3 (each depolarized pulse D1-D3 preferably after each Apply the resting phase (DW1-DW3).

For convenience of explanation, charge pulses and depolarization pulses are described as square pulses, although in practical practice they are often not suitable and therefore it should be appreciated that the present invention includes, but is not limited to, square waveforms. Also, not intended to be limiting but merely for convenience, the charging pulses C1, C1 'are shown as having the same pulse width and the same charging current amplitude IA, while the depolarized pulses D1-D3 have the same pulse width and the same discharge. It is shown as having a current amplitude (IB). In addition, the number of depolarized pulses shown is purely for convenience and not limiting. Resting periods (CW1) and (DW1-DW3) are shown for convenience only and are not limited thereto. The controller 13 can change the duration of this rest period based on the monitored change in battery state of charge.

First, with respect to the comparison of voltage measurements taken at different resting periods, specific voltage measurements V1 and V2 are shown on the voltage waveforms in FIGS. 2A-2B. (V1) and (V2) are output voltage measurements of the battery taken when the battery is in open circuit form during the resting periods DW1 and DW2, respectively. As long as the subsequent output voltage measurement V2 is taken at the same relative time point in the next resting period DW2, the first output voltage measurement V1 can be made at the beginning, middle, or end of the resting period DW1. According to the present invention, the voltage level during the resting periods DW1-DW3 is measured and evaluated.

In FIG. 2A, it is shown that voltage V1 is approximately equal to voltage V2. This approximate equivalence in voltage indicates that the battery is not overcharged. Thus, the charging current IA does not need to be adjusted.

In FIG. 2B, the voltage V1 is greater than the voltage V2. If the difference between (V1) and (V2) in FIG. 2B is 10 mV / cell or less, the charging current IA need not be adjusted. However, if the difference between (V1) and (V2) in FIG. 2B is 10 mV / cell or more, this decrease in (V1) to (V2) in voltage suggests that the battery is overcharged. This may be due to the battery reaching full charge or due to the battery being unable to accept the full charge current IA for the duration C1 for some reason. Therefore, the charging current IA must be reduced until the difference is less than 10 mV / cell.

3 is a flow chart of measuring battery charge by comparing voltage measurements taken during one or more idle periods. In step 301, an initial charging parameter such as the battery voltage or the number of cells in the battery and the discharge rate C for the battery is set by the user. The controller 13 then measures the charge current IA and the depolarization current IB for the battery. This procedure may preferably be based on a lookup table or a formula.

In step 303, the controller 13 applies a charging pulse C1 of current amplitude IA to the battery (preferably but not necessarily followed by the resting period CW1) and then depolarizing pulse ( D1) is applied to the battery of current amplitude IB. The controller 13 waits for a predetermined period of time DW1 and measures the output voltage V1 of the battery at a predetermined time in the resting period DW1. The controller 13 then applies another depolarized pulse D2 of current amplitude IB to the battery. The controller again waits for a predetermined period of time DW2 and measures the other output voltage V2 of the battery at the corresponding scheduled time in the second resting period DW2. The first output voltage measurement V1 is performed at the beginning, middle, or end of the first resting period DW1 as long as the subsequent output voltage measurement V2 takes at the same relative time point to the beginning of the resting period in the next resting period DW2. Can be.

Decision 309 tests whether the difference V1 -V2 is greater than some maximum difference voltage VDMAX. If not, the battery is not yet charged and the average charge current does not need to be adjusted. In this case, the controller 13 will proceed to step 313.

If VD> VDMAX, the battery is overcharged or charged at a greater rate than the battery can adequately accommodate. Thus, in step 311 the controller 13 reduces the average charge current. The controller 13 then proceeds to step 313.

In step 313, the controller 13 determines whether or not to terminate the pulse charging process. The pulse charge cycle can end for one of several reasons. For example, the charging time set by the user may expire, the battery temperature may be outside the acceptable range, or the amplitude of the charging current IA may be reduced below C / 10.

If the reason for the termination of the pulse charging process occurs in step 315, the controller 13 terminates the pulse charging process and switches to trickle charging when the other charging process is terminated, for example, because the charging current is C / 10. Alternatively, the controller 13 will completely stop the charging process if, for example, the time has expired or the termination has occurred for reasons that temperature is unacceptable. In addition, a visual or audible indication of the end of the filling process may be provided to the operator.

In step 313, the controller 13 measures that the pulse charging process is not terminated and the controller 13 returns to step 303 accordingly.

4 shows waveforms illustrating the battery charging process and how the battery condition is measured. In this procedure, the open circuit battery voltage is measured at the beginning and end of the resting period. For convenience of explanation, not for the purpose of limitation, the voltage has been shown to be essentially constant during the rest period. However, in practice, the voltage may vary during the rest period, which provides additional information regarding the state of the battery, in particular lead-acid and NiCd batteries. If the voltage drops above a predetermined amount during the resting period (VD1 = V5-V6 and VD1> VD1MAX), the electrolyte concentration is higher than normal and water must be added to the battery. Audible and visible alarms can be used to alert the operator to this condition and the charging process can be terminated automatically. Preferably, the measurement is performed during the first rest period DW1.

In addition, voltage measurements at the beginning and end of one resting period (V5 and V5, respectively) differ by more than a certain predetermined amount (VD1 = V5-V6 and VD1> VD2MAX), and voltage measurements at the beginning and end of subsequent resting periods ( When V7 and V8, or V9 and V10, respectively) also differ by more than a predetermined amount (VD2 = V7-V8 and VD2> VD2MAX), this result indicates that the battery is not properly charged and therefore the charging process must be terminated. Instruct.

5 is a flowchart illustrating an alternative method of measuring a battery condition. The process of FIG. 5 is the same as that of FIG. 3 except that step 503 replaces step 303, and decision 513 illustrates some of the terminating steps of decision 313. In step 513, additional voltage measurements V5, V6, V7, V8 are taken and the voltage differences VD1 and VD2 are measured.

At decision 513A, the controller 13 measures whether the voltage difference VD1 is greater than the predetermined maximum difference VD1MAX. In that case, then in step 513B the controller 13 issues an alarm to signal the operator to apply water to the battery and then terminates the charging process. Otherwise, at decision 513C, the controller measures whether (VD1) is greater than the predetermined maximum (VD2MAX) and (VD2) and is greater than (VD2MAX). If both conditions are met, the controller 13 terminates the charging process. The controller 13 may also signal the operator to terminate. Otherwise, the controller 13 returns to step 503.

In the present invention, as described above, the charging current adjusts (IA), adjusts the duration of the charging pulse, adjusts the repetition rate of the charging pulse, adjusts the number or duration of the depolarized pulse, Can be adjusted by adjusting the duration of one or more of CW1, DW1, DW2, etc.). Preferably, when the charging current is adjusted, the depolarization current degree is similarly adjusted, such as adjusting the IB, adjusting the duration of the depolarizing pulse, or adjusting the number of depolarizing pulses between the respective charging pulses.

As an example of this process, for lead-acid sealed batteries with a 0.62 amp-hour rating (C = 0.62), IA is 2.4 amps for 150 milliseconds, IB is 5 amps for 2 milliseconds, and DW1 and DW2 are 12 milliseconds. The repetition rate (approximately 2 charge pulses per second) of the charge pulses is a value such that the average charge current is 0.75 amps (about 1.2 C). CW1 may be used or may not exist. In this example, when the average charging current drops to 0.0623 amps (0.1C), the pulse charging process will terminate. As another example, for a lead-acid sealed battery of 52 amp-hour rating (C = 52), IA is 100 amps and IB is 250 amps, and the duration of the charge pulse is 60 amps (approximately 1.2 C). The pulse charging process will be terminated when the average charging current drops to 5.2 amps (0.1C).

The comparison of the measured battery output voltage during the continuous rest period after the depolarization pulse gives a better state of charge indicator than in the prior art. As a result, this method charges the battery as quickly as possible (1), avoids heating and damaging the battery which may result from continuous charging or overcharging (2) and allows premature termination or modification of the charging process without overcharging the battery. do.

Although it may be desirable to use the battery voltage measured during DW1 and DW2, the present invention is not so limited. The battery voltage can be measured during two consecutive or discontinuous discharge breaks that are not separated by a charge pulse. For example, (DW2) and (DW3) may be used, or (DW1) and (DW3) may be used.

In addition, the depolarized pulses can have the same amplitude or different amplitudes. Likewise, depolarized pulses can have the same duration or different durations. Resting groups can also have the same duration or different durations.

Although the invention has been described in detail in particular with respect to sealed lead-acid batteries, the invention is not so limited. The present invention is also useful for other types of batteries such as NiCd, NiMH, nickel-iron, nickel-zinc, silver-zinc, lithium-metal oxides, lithium ion-metal oxides, non-sealed lead-acids and the like.

From the foregoing description, it will be appreciated that the present invention provides a method and apparatus for rapidly charging a battery in a manner that does not result in overheating of the battery.

It will also be appreciated from the foregoing description that the present invention provides a method and apparatus for charging a battery at a rate that the battery can accept without damage.

The present invention also provides a method and apparatus for measuring battery condition, including determining whether water should be added to the battery.

By reading the above description of the preferred embodiments of the present invention, modifications and variations are possible to those skilled in the art. Accordingly, the scope of the present invention is limited only by the claims.

Claims (15)

Applying a charging pulse providing an average charging current, applying a first depolarization pulse, waiting for a first rest period, measuring a voltage of the battery at a predetermined point in the first resting period, applying a second depolarization pulse, and 2 Waiting for the resting period, measuring the voltage of the battery at a predetermined time in the second resting period, measuring the difference between the voltage at a predetermined time in the first resting period and the voltage at a predetermined time in the second resting period, and then the difference is scheduled Reducing the average charge current if greater than the threshold. The method of claim 1, further comprising applying a charging pulse, applying first and second depolarized pulses, waiting for the first and second rest periods, and repeating the voltage measurement steps in the first and second rest periods. Way. Applying a charging pulse providing an average charging current, applying a first depolarization pulse, waiting for a first rest period, measuring a voltage of the battery at a predetermined point in the first resting period, applying a second depolarization pulse, and Waiting for a rest period, applying a subsequent depolarization pulse, waiting for a subsequent rest period, measuring the voltage of the battery at a predetermined time in the subsequent resting period, a voltage at a predetermined time in the first resting period and a voltage at a predetermined time in the subsequent resting period Measuring the difference between and then reducing the average charge current if the difference is greater than a predetermined threshold. 4. The method of claim 1 or 3, wherein the charge pulse has a predetermined charge pulse duration and the step of decreasing the average charge current comprises a decrease of the charge pulse duration. 4. A method according to claim 1 or 3, wherein the charging pulse has a predetermined charging pulse current amplitude and the step of decreasing the average charging current comprises a reduction of the charging pulse current amplitude. 4. The method according to claim 1 or 3, wherein the charging pulse has a predetermined charging pulse repetition rate and the decreasing step of the average charging current comprises a decreasing charging pulse repetition rate. 4. The method of claim 1 or 3, wherein each depolarized pulse has a predetermined depolarized pulse current amplitude, and further comprising the step of decreasing the depolarized pulse current amplitude when the average charge current decreases. 4. The method of claim 1 or 3, wherein the depolarized pulse has a predetermined depolarized pulse duration, and further comprising the step of decreasing the depolarized pulse duration when the average charge current decreases. 4. The method of claim 1 or 3, wherein the plurality of depolarized pulses further comprises a step of decreasing the number of depolarized pulses when each charge pulse is followed and the average charge current decreases. 4. The method of claim 1 or 3, wherein the depolarized pulse has a predetermined depolarized pulse duration and the step of decreasing the average charge current comprises an increase in the depolarized pulse duration. 4. The method of claim 1 or 3, wherein each resting period has a predetermined resting period duration and the step of decreasing the average charge current comprises increasing the resting period duration. 4. A method according to claim 1 or 3, wherein each charge pulse is followed by a plurality of depolarization pulses and the step of decreasing the average charge current comprises an increase in the number of depolarization pulses. Apply a charge pulse, apply a first depolarization pulse, wait for a first rest period, measure the voltage of the battery at a first predetermined time within the first rest period, apply a second depolarization pulse, and wait for a second rest period Measure the voltage of the battery at the scheduled time in the second pause, measure the difference between the voltage at the scheduled time in the first pause and the scheduled time in the second pause, and then pulse if the difference is greater than the predetermined threshold. Comprising the step of terminating the charging process, the battery charging method by the pulse charging process. Applying a charge pulse to the battery, applying a first depolarization pulse to the battery, waiting for a first rest period, measuring a voltage of the battery at a first predetermined time point in the first resting period, and measuring the battery at a second predetermined time point in the first resting period Measure the voltage of the battery, apply a second depolarization pulse to the battery, wait for the second pause, measure the difference between the voltage at the first predetermined time point and the voltage at the second predetermined time point, and then the difference If greater, indicating that water should be added to the battery. Applying a charging pulse to the battery, applying a first depolarization pulse to the battery, waiting for a first rest period, measuring a voltage of the battery at a first predetermined time point in the first resting time, and at a second predetermined time point in the first resting time Measuring a voltage of the battery, applying a second depolarization pulse to the battery, waiting for a second rest period, measuring a battery voltage at a first predetermined time point in the second rest period, and measuring a second predetermined time point in the second rest period. Measuring a battery voltage, measuring a first difference between a voltage at a first predetermined time point in the first resting period and a voltage at a second predetermined time point in the first resting period; Measuring the second difference between the voltages at the second scheduled time in the resting period and then terminating the charging process if the first difference is greater than the predetermined threshold and the second difference is greater than the predetermined threshold. Method terminates the charging process of the Li