Abstract: Provided are a portable electronic device which accurately judges service life of a battery even when the battery is replaced, and a method for controlling such portable electronic device. A control block (48) is provided with a voltage measuring section (100), which is connected to a rechargeable battery (32) and measures a voltage value of the rechargeable battery (32); and a control section (101), which measures the voltage of the rechargeable battery (32) by means of the voltage measuring section (100) each time recharging of the rechargeable battery (32) is started and ended, and controls to store recharge count information specified based on the measured voltage value in a storage section (42).

Abstract: In a lifetime estimating method for a rechargeable lithium battery, the open circuit voltages of the rechargeable lithium battery after discharging for at least two different charge/discharge cycle numbers are detected while charge/discharge cycles go on. Next, at least the two of the voltage values are plotted for respective cycle numbers, and a circular arc passing the plotted points is drawn. Furthermore, the lifetime of the rechargeable lithium battery is estimated based on a size of the circular arc. The progression of deterioration can be suppressed by controlling the charge and discharge of the rechargeable lithium battery based on the lifetime estimation.

Abstract: There is provided a measuring system capable of rendering a power source voltage of an internal circuit higher than a drivable voltage of the internal circuit by removing or reducing a chloride film with greater certainty, thereby enabling operation, and initial activation of the internal circuit to be normally executed, or preventing the internal circuit from running away. The measuring system comprises a thionyl chloride based primary cell, a cell voltage measurement unit, and an internal circuit provided with state-transition controller wherein in the case of transition of the internal circuit to a state thereof, having a discharge current larger than the discharge current in the present state thereof, the transition is made according to results of comparison of a voltage measured by the cell voltage measurement unit with a threshold on the basis of a discharge current in a state before, or after the transition of the internal circuit.

Abstract: An apparatus estimates SOH of a battery based on a battery voltage variation pattern. A data storing unit obtains and stores battery voltage, current and temperature data from sensors, at each SOH estimation. A first SOC estimating unit estimates first SOC by current integration using the battery current data. A second SOC estimating unit estimates open-circuit voltage from the voltage variation pattern, and calculates and stores second SOC corresponding to the open-circuit voltage and temperature using correlations between the open-circuit voltage/temperature and SOC. A weighted mean convergence calculating unit calculates and stores convergence value for weighted mean value of ratio of the second SOC variation to the first SOC variation. A SOH estimating unit estimates capacity corresponding to the weighted mean convergence value using correlation between the weighted mean convergence value and the capacity, estimates relative ratio of the estimated capacity to an initial capacity, and stores it as SOH.

Abstract: A contactless charging system is made up of an electronic device and a contactless charger 200 that recharges the electronic device in a contactless manner. The electronic device transmits a full charge command indicating completion of charge. Upon receipt of the full charge command, the contactless charger shifts to a charge stop state in which charge of the electronic device is not performed. In the charge stop state, the contactless charger generates a load check signal for checking whether or not the electronic device is placed in the contactless charger in a rechargeable state, and transmits the signal. Further, the contactless charger also generates a charge restart check command for checking whether or not the electronic device requests recharge in a charge stop state, and transmits the command.

Abstract: An electric energy storage device has a housing, a positive pole and a negative pole, and a deep discharge device integrated in the housing. The device further has a discharge load and it is configured such that the two poles can be electrically connected by way of the discharge load. There is enabled targeted and controlled deep discharging of the energy storage device and improved operating reliability.

Abstract: A battery charging apparatus and method adapted to reduce battery capacity as a function of increased temperature thereby permitting partial charges at temperatures in excess of manufacturer's recommendations. The method includes steps of reducing charging current and charging voltage as a function of battery temperature thereby averting chemical instability within the battery. The apparatus detects battery temperature and includes a controller that will control charger voltage and current as a function of temperature and determine a suitable charging capacity.

Abstract: A passive battery discharge apparatus located within a cap. The cap extends over battery contacts to be discharged. The discharge apparatus includes a conductive material with specified volumetric resistivity properties that is formed into a pad. The cap is positioned over the contacts so that the pad touches and spans between the contacts to be discharged. A spring insures good contact between the pad and the battery contacts. A metal heat sink provides added thermal control. The discharge apparatus provides an economical solution to safely transport batteries that are beyond their useful service life by avoiding circuit components in favor of conductive elastomers or conductive foams.

Abstract: Supplemental lithium can be used to stabilize lithium ion batteries with lithium rich metal oxides as the positive electrode active material. Dramatic improvements in the specific capacity at long cycling have been obtained. The supplemental lithium can be provided with the negative electrode, or alternatively as a sacrificial material that is subsequently driven into the negative electrode active material. The supplemental lithium can be provided to the negative electrode active material prior to assembly of the battery using electrochemical deposition. The positive electrode active materials can comprise a layered-layered structure comprising manganese as well as nickel and/or cobalt.

Abstract: A battery charger capable of correcting the deterioration of a secondary battery left unattended in a charge state and capable of accurately grasping a residual capacity. A battery pack having a nonvolatile memory and a secondary battery cell is attached to the battery charger. Full charge capacity data indicating a chargeable capacity of the battery pack at full charge and a left-charged battery deterioration correcting table to correct the full charge capacity data in accordance with the number of charge cycles are read out from the nonvolatile memory. The charged state data is counted each time it is stored in the nonvolatile memory. A battery cycle deterioration correcting value is specified based on the number of charge cycles, and full charge capacity data is corrected using the specified correcting value. The full charge capacity stored in the nonvolatile memory is rewritten.

Abstract: The present invention discloses an overvoltage protection (OVP) circuit for use in a charger circuit system, comprising: a power transistor electrically connected between a voltage supply and a battery; an OVP circuit which turns off the transistor when a voltage supply exceeds a threshold value; and a multiplexing circuit electrically connected between an output of the OVP circuit and the gate of the transistor. The present invention also discloses a charger circuit with an OVP function, comprising: a single power transistor electrically connected between a voltage supply and a battery; an OVP control circuit which turns off the power transistor when a voltage supply exceeds a threshold value; and a charger control circuit which controls the gate of the power transistor to determine a charge current to the battery when the voltage supply does not reach the threshold value.

Abstract: A system and method adapted to rejuvenate batteries at or near the resonant frequency of the battery. The present invention takes a battery and applies a modulated current charging signal to increase battery performance. A resonant signal is adapted to re-train and adjust battery materials for proper operation. By repeated charge/discharge cycling, battery memory decreases and/or battery capacity increases, thereby improving the battery capacity.

Abstract: An apparatus estimates SOH of a battery based on a battery voltage variation pattern. A data storing unit obtains and stores battery voltage, current and temperature data from sensors, at each SOH estimation. A first SOC estimating unit estimates first SOC by current integration using the battery current data. A second SOC estimating unit estimates open-circuit voltage from the voltage variation pattern, and calculates and stores second SOC corresponding to the open-circuit voltage and temperature using correlations between the open-circuit voltage/temperature and SOC. A weighted mean convergence calculating unit calculates and stores convergence value for weighted mean value of ratio of the second SOC variation to the first SOC variation. A SOH estimating unit estimates capacity corresponding to the weighted mean convergence value using correlation between the weighted mean convergence value and the capacity, estimates relative ratio of the estimated capacity to an initial capacity, and stores it as SOH.

Abstract: In a pre-replacement process, a replacement battery module is provided with a memory effect before being dispatched, by performing at least one of the process of performing a cyclic charge/discharge operation on the replacement battery module while limiting the width of SOC change to an intermediate range, and the process of setting an initial SOC and then letting the replacement battery module stand for a predetermined time in an environment of temperature above normal temperature. This pre-replacement process substantially eliminates the difference between the voltage characteristic of the replacement battery module yet to be used and the voltage characteristic of a battery module having a history of use, thereby achieving a uniform voltage characteristic of a battery pack as a whole.

Abstract: A method for extending the service life of a portable device includes monitoring a battery of a portable device; identifying a problem bank; reconfiguring a connection schema for the battery to replace the problem battery bank with at least one spare bank; conditioning or exercising the problem bank; connecting the portable device to a power supply to recharge the problem bank; and reconnecting the recharged or repaired bank according to the connection schema without the at least one spare bank. A method for extending the service life of a portable device includes monitoring power consumption of at least one of the hardware or software of a portable device; and reconfiguring the connection schema of the battery banks to redistribute power consumption of at least one of the hardware or software.

Abstract: A quick conditioning cycle system to avoid performance degradation at the end of calibrating cycle. The quick conditioning cycle system discharges a battery to a level where battery remaining capacity is still high enough to backup memory at a guaranteed period of time. During the quick learning cycle, the battery pack is discharged from a full charge. If measured capacity exceeds a predetermined threshold (Cpc), calibration stops. Otherwise, the quick conditioning cycle system reports a defected battery when measured capacity is less than Cpc and continues discharging to a full conditioning cycle, if desired.

Abstract: A power supply system for portable equipment has a lithium-ion secondary battery as a power supply, a temperature detection portion for detecting a temperature of the power supply, a voltage detection portion for detecting a voltage of the power supply, a memory portion, and a forced discharge portion. The memory portion stores a control operating temperature, a control operating voltage and a control termination voltage. The forced discharge portion recognizes an abnormality of the power supply when the temperature of the power supply is at least the control operating temperature and the voltage of the power supply is at least the control operating voltage. Then, the forced discharge portion electrifies the notification portion and makes it inform a message indicating that the abnormality is being avoided. The forced discharge portion forcedly discharges the power supply until the voltage of the power supply reaches the control termination voltage.

Abstract: An apparatus and method for discharging a voltage in a battery pack. The apparatus includes a discharge resistance connected to a discharge target battery of plural batteries in the battery pack and discharging a voltage of the discharge target battery, a switching section for connecting the discharge target battery and the discharge resistance, a voltage measuring section for measuring a voltage of the discharge target battery, and a control section for controlling the switching section depending on the measured voltage value of the battery. The method includes measuring a voltage of the discharge target battery, calculating a PWM duty rate of a switching section connecting the discharge target battery and a discharge resistance using the measured voltage value and a value of the discharge resistance, and controlling the switching section based on the duty rate to maintain an energy consumed in the discharge resistance to be constant.

Abstract: According to the invention, an apparatus for robust battery discharge which provides uninterrupted power to a discharge circuit used in a discharge cycle is disclosed. The apparatus may have a discharge circuit for discharging a battery. The discharge circuit may be adapted to be coupled with a discharge load and configured to discharge the battery using the discharge load during a discharging cycle. The apparatus may have a first power input and a second power input, which may configured to receive power from a first power source and a second power source, respectively. The power inputs may be further configured to supply power to the discharge circuit. The apparatus may have a power switching circuit for switching power from the first power source to the second power source when the first power source is interrupted. The second power source may be the battery.

Abstract: A method for efficiently charging a battery. The method includes producing a first signal having a voltage level dependent on the voltage of the battery, comparing the voltage level of the first signal with a settable voltage representative of a maximum battery charging current, and producing a second signal representative of a charging current to be provided to the battery, the second signal having a voltage level selected to be the lower voltage level between the first signal and the settable voltage.

Abstract: Methods and systems are disclosed for charge current adjustment to enhance battery cycle life thereby allowing batteries to be charged quickly without accelerating the aging process of the battery. As the charge capacity of the battery degrades over time, the charge current for the battery charging cycles is also reduced so that the effective charge rate for the battery is adjusted to account for the reduction in charge capacity. In this way, battery capacity life is enhanced by avoiding an accelerated charge rate as the battery capacity drops over the operational life of the battery. The methods and systems disclosed are useful for battery-powered information handling systems, as well as other devices where fast charging and long cycle life is desirable, such as cell phones, personal digital assistants (PDAs), electric vehicles and/or any other battery powered devices.

Abstract: The present invention provides a charging device with battery capacity analysis function, wherein a charging device includes a control unit, a computing unit, a display unit, a charging unit and a discharging unit. When the charging unit is connected to and charging a battery, the control unit determines whether the power of the battery is fully charged or not, and after the battery is fully charged, then the charging unit stops charging, and at the same time the discharging unit implements discharging of the battery. Moreover, the control unit controls stopping of electric discharge after the battery power is exhausted, which enables the computing unit to determine and calculate actual effective capacity of the battery, and enables the display unit to display the calculated capacity data, after which fully charging of the battery continues, thereby enabling the charging device to achieve battery capacity analysis and charging effectiveness.

Abstract: A charging and discharging control circuit controls charging and discharging of a secondary battery by monitoring at least one of a voltage across, and an electric current through, the secondary battery and controlling a switching circuit in a charging and discharging pathway of the secondary battery. A charging and discharging switch control circuit controls the switching circuit. A driver circuit outputs a signal from the charging and discharging switch control circuit to the switching circuit through an output terminal. A logic circuit compares a voltage of the signal from the driver circuit with a voltage applied to the output terminal from an external portion. The charging and discharging control circuit is switched between a normal operating state and a testing state in accordance with a result of the comparison by the logic circuit.

Abstract: A battery testing apparatus includes a charge circuit, a discharge circuit, a computer, and a control circuit. The charge circuit is coupled to a direct current (DC) adapter, the DC adapter charges a battery through the charge circuit. The discharge circuit is coupled to the battery and configured to discharge the battery. The computer records charge/discharge time and charge/discharge cycles of the battery, and calculates capacity and cycle life of the battery according to the time and cycles of charge and discharge. The control circuit has an input terminal coupled to the computer, and a plurality of output terminals respectively coupled to the charge circuit and the discharge circuit, the control circuit controls the charge and discharge circuits charging and discharging the battery.

Abstract: The present invention discloses a method for predicting the voltage of a battery, in particular a vehicle battery. The method according to the invention makes it possible to predict a voltage drop before it actually occurs as a result of a load. For this purpose, a filtered battery voltage and a filtered battery current are first of all determined from battery data, such as the battery voltage, the battery current, the battery temperature and the dynamic internal resistance. The resistive voltage drop across the dynamic internal resistance is determined from the difference current between the filtered battery current and the predetermined load current. Furthermore, a polarization voltage is calculated as a function of the filtered battery current, and is then filtered. The predicted battery voltage is calculated from the filtered battery voltage, minus the resistive voltage drop and the filtered polarization voltage. A decision on further measures can be made on the basis of this predicted battery voltage.

Abstract: A battery control for an electric motor powered device such as a golf car that includes a battery control and charging method that prolongs the life of the battery by controlling the method and rate of charging and discharging and preventing charging when it could be detrimental to the battery,.

Abstract: A method for training a support vector machine to determine a present state of charge of an electrochemical cell system includes choosing a training data, preprocessing the training data, finding an optimal parameter of the support vector machine, and determining support vectors.

Abstract: To provide a method of controlling charge and discharge of a secondary battery for automatic guided vehicle that can decide the timing of refresh charge and discharge accurately and minimize the frequency of refresh charge and discharge.

Abstract: A method for charging a lead acid storage battery to advantageously extend its life is described. The termination of a charging process is based upon an evaluation of the first derivative (dv/dt) and second derivative (d2v/dt2) of the applied charging voltage. By utilizing the first derivative (dv/dt) and second derivative (d2v/dt2) as charging criteria, an amount of overcharge is applied to the battery that takes into account the precise amount of amp-hours previously removed from the battery. A charger arrangement for performing a charging process of the invention also is described.

Abstract: This invention includes a circuit for displaying charge status to a user. The circuit includes circuitry for comparing a supply or reference voltage to a cell voltage, circuitry for sensing charging current and circuitry for displaying at least one of three charging states to a user. The circuit compares the supply or reference voltage to the cell voltage while sensing current. If the difference between the supply or reference voltage is great, and current is small, the circuit indicates a trickle charging mode. If the charging current is large, the circuit indicates rapid charge. If the difference between the supply or reference voltage is small, and the current is small, the circuit indicates a top off mode. The circuit preferably includes a plurality of comparators for both sensing and comparing the voltages and currents. A pair of light emitting diodes preferably indicates the state of charge to the user.

Abstract: A battery cell balancing system (12) for a battery (30) having a plurality of cells (32) is provided. The system (12) includes a power supply (38) and a plurality of transformer/rectifier circuits (34) electrically coupled to the cells (32). Preferential charging occurs for a cell with the lowest state of charge. At least one current limiting device (36) is electrically coupled to the transformer/rectifier circuits (34) and the power supply (38). The current limiting device (36) buffers a source voltage from a reflected voltage of at least one of the plurality of cells (32). A method of performing the same is also provided.

Abstract: A battery-condition detection which requires no current sensor. The battery is connected to a microprocessor via a circuit configuration. This circuit configuration includes means for the voltage measurement, means for the voltage comparison and, optionally, for the temperature measurement, as well as means for generating a trigger pulse. This trigger pulse generates a voltage pulse at the battery. After averaging or filtering, the pulse response is utilized for determining the complex internal resistance of the battery, from which the battery condition is then estimated.

Abstract: This method of charging includes a method of terminating charge when three events have occurred: a voltage across at least one of the cells reaches a predetermined maximum voltage, the average charging current falls below a predetermined minimum current, and the presence of a power source has been detected. The method also includes a safety termination that prohibits charge upon the expiration of a timer when the cells have stored little or no energy.

Abstract: Power supply apparatuses and methods of supplying electrical energy are provided. According to one aspect, a power supply apparatus includes an electrochemical device configured to store electrical energy, a first interface coupled with the electrochemical device and adapted to couple with a supply configured to provide electrical energy and a first load configured to receive electrical energy, and charge circuitry coupled intermediate the first interface and the electrochemical device, wherein the charge circuitry is configured to monitor a quantity of electrical energy supplied from the supply to the first load and to control a supply of electrical energy to the electrochemical device responsive to the monitoring and to charge the electrochemical device.

Abstract: A power charger which charges and provide conditioned power from at least one of a super-capacitor and a secondary battery. The type of energy device is user selectable, such that the user can select super-capacitors because of their much longer charge/discharge life and low-maintenance requirements, while another user can chose secondary batteries because of their higher stored energy, while a third user may select a combination of the two.

Abstract: A method of detecting and resolving a memory effect capable of detecting the memory effect with ease and with high precision and resolving even when the vehicle is in motion is provided. A current in a secondary battery is detected, a variation &Dgr;SOC in a residual battery capacity for a predetermined time period is calculated according to at least current integration by multiplying the detected current by a predetermined charge efficiency (S302), a temperature of the secondary battery is detected and a variation &Dgr;V in a no-load voltage for the predetermined time period is calculated based on the detected current, and an internal resistance corresponding to the detected temperature and the SOC is calculated (S303). A ratio k of the variation in the no-load voltage to the variation in the residual battery capacity is calculated (S304).

Abstract: The present invention provides a method for controlling battery charging and discharging in which a battery is charged and discharged such that a SOC (state of charge) value of the battery is increased/decreased to a predetermined range when the SOC value of the battery is in a predetermined range; and a range of the SOC values in which charging and discharging processes are performed sequentially varies and a range of the SOC values after the charging and discharging processes also sequentially varies.

Abstract: A battery control system capable of relatively smoothly canceling memory effects caused to a battery mounted on a hybrid vehicle, while avoiding deterioration of the battery and vehicle performance. Upon detection of generation of charge memory effects, an HVECU changes the center of a control range for the battery's charged amount (SOC) from its ordinary value to a value in the vicinity of an upper limit of an appropriately charged range. This SOC control is continued for a predetermined amount of time for cancellation of charge memory effects. Under such control, SOC basically varies within a range lower than where excessive charging may possibly be caused, so that battery deterioration due to excessive charging and droped power consumption due to prohibited charging can be prevented.

Abstract: A method to extend the functionality of a battery, the method comprising drawing a current greater than the minimum rejuvenation current from the battery thereby increasing a functionality of the battery.

Abstract: A method to extend the functionality of a battery, the method comprising drawing power from the battery, and repetitively drawing a current pulse greater than the minimum conditioning current from the battery, thereby conditioning the battery.

Abstract: A device and a method are provided in which memory effects can be cancelled by controlling charging and discharging of a secondary battery during driving of a vehicle. When a memory effect determinator determines that the discharging memory effect has occurred, based on at least one of the following determinations: whether a time of charging/discharging of a secondary battery has reached a predetermined time; whether a charging/discharging amount in the secondary battery has reached a predetermined amount; and whether a voltage per cell has reached a voltage V1 at a lower-limit state of charge in a range of capacity actually used, a discharging controller discharges the secondary battery until the voltage per cell reaches a voltage V3 that is higher than 1.0 V and is lower than the voltage V1 at the lower-limit state of charge.

Abstract: A charge maintenance system for a lead-acid battery includes a charger, a voltage monitor, and a load/switch series combination, all connectable in parallel across the battery terminals, the switch and the charger being under control of a microprocessor. The battery is initially loaded for a predetermined time period, or until the battery voltage drops below an absolute minimum reference level during a loading cycle, and the system stores the lowest battery terminal voltage occurring during the loading cycle. After a predetermined delay following the loading cycle the charger is activated to charge the battery until it reaches a maximum charge level. Then, if the stored lowest battery voltage level is below a predetermined reference level, the loading/charging routine is repeated, otherwise it is not and the battery is considered good.

Abstract: This invention includes an apparatus and method of initiating reconditioning of a rechargeable battery cell without an auxiliary mechanical switch. When a battery is inserted into the charger, the charger identifies the battery. The charger determines whether to charge or recondition the battery based upon factors like chemistry and prior usage. The charger then begins either a charge or reconditioning cycle and indicates such to the user. The user may override the charger's decision by removing the battery from the pocket, at which time the charger starts a window timer. If the battery is reinserted prior to the expiration of the window timer, the charger stops the charge or reconditioning cycle and begins the corresponding opposite, i.e. it stops charging and begins reconditioning, or it stops reconditioning and begins charging.

Abstract: A battery charger for a lead acid battery having a power supply with an input connected to an AC signal and an output connected to the battery. The power supply provides a charge current to the battery. A clock connected to the AC signal provides clock pulses having transitions synchronized with zero crossings of the AC signal. A voltage monitor connected to the battery detects a battery voltage substantially simultaneously with a zero value of the charge current. A charge mode control is connected to the clock and the voltage monitor for commanding different battery charge currents. The voltage monitor includes a temperature compensation circuit. The battery charger includes a display module that can be placed at a location remote from the battery charger and convenient to the user.

Abstract: Electrodes for secondary (rechargeable) batteries are fabricated using active material particles such as flakes, fingers, projections, needles, threads, fibers, pods, hairs, ribbons and the like, which have an aspect ratio of at least 1:3:1. The high aspect ratio, in combination with relatively shallow discharge cycles, provides high power of at least 800 W/kg sustainable over at least ten seconds, high energy of at least 7 W-hr/kg, and a high cycle life of at least 250 cycles. Selection of parameters also provides power to energy ratios for high power, high energy batteries of at least 10. Preferred chemistries for the novel batteries include lithium ion, and preferred active materials include carbon, metal oxides and metal. Batteries including the novel technology can advantageously be used in electric vehicles, consumer electronics, electrical appliances, and industrial applications such as battery backup systems and switches.

Abstract: The present invention provides a method for cycling a battery, containing lithium metal oxide, particularly lithium manganese oxide (LMO) active material, in a cell in a manner which reduces the extent to which loss of capacity occurs. The present method of operation extends the cycle life of such battery.

Abstract: In a preferred embodiment, a method of condition monitoring of an opportunity charged battery, including: determining length of time the battery has been off-line; determining whether charging of the battery has occurred during the length of time; if step (b) results in a determination that the charging of the battery has occurred, determining degree of charging of the battery occurring during the length of time; and if step (b) results in a determination that charging of the battery has occurred, resetting a condition monitor associated with the battery to reflect the degree of charging of the battery.

Abstract: A method and apparatus for reconditioning and charging a battery is disclosed. The lead-acid battery rejuvenator apparatus comprises of an oscillator, a frequency divider and a pair of transistors. The oscillator outputs a frequency signal. The frequency divider receives the frequency signal and splits the frequency signal into a plurality of non-overlapping operating frequency signals. These operating frequency signals are sent to respective operating frequency output terminals. The three terminals of a first transistor are electrically connected to one terminal of an inductor, the negative terminal of the lead-acid battery and one of the operating frequency output terminals. The other terminal of the inductor is electrically connected to the negative terminal of the lead-acid battery. The three terminals of a second transistor are electrically connected to one terminal of a resistor, the negative terminal of the lead-acid battery and another operating frequency output terminal.

Abstract: A method and apparatus for reconditioning and charging a battery is disclosed. The lead-acid battery rejuvenator apparatus comprises of an oscillator, a frequency divider and a pair of transistors. The oscillator outputs a frequency signal. The frequency divider receives the frequency signal and splits the frequency signal into a plurality of non-overlapping operating frequency signals. These operating frequency signals are sent to respective operating frequency output terminals. The three terminals of a first transistor arc electrically connected to one terminal of an inductor, the negative terminal of the lead-acid battery and one of the operating frequency output terminals. The other terminal of the inductor is electrically connected to the negative terminal of the lead-acid battery. The three terminals of a second transistor are electrically connected to one terminal of a resistor, the negative terminal of the lead-acid battery and another operating frequency output terminal.

Abstract: In a method of charging a battery cell, having a positive terminal and a negative terminal, a charging current is applied to the battery cell. A voltage is measured between the positive terminal and the negative terminal. The charging current is removed from the battery cell at a predetermined period subsequent to when the voltage changes at a rate, relative to time, that is not greater than a predetermined threshold. A battery cell charger for charging a battery cell includes a charger circuit, capable of applying a charging current to the battery cell, a voltage sensor circuit that measures a voltage between the positive terminal and the negative terminal and a charger control circuit that is responsive to the voltage sensor.