Abstract: There is disclosed a power supply for storing electrical energy in capacitors connected in series, the power supply having a function of shorting out capacitors at fault. Shorting means are connected in parallel with the capacitors, respectively. If any one of the capacitors is charged abnormally, it is detected by detection means. The terminals of this detected capacitor are shorted out by the corresponding one of the shorting means. The shorting means can also act as bypass means ancillary to parallel monitors, respectively. By detecting temperature rises of the bypass means, abnormal charging of the capacitors can be judged.

Abstract: Methods and apparatus are disclosed for inputting messages and other infotion, such as advertisements, to a vehicle while the vehicle is coupled to a local station, such as a recharging station or a refueling station. The messages can be selected in accordance with information received from the vehicle, including information that selectively identifies one, some, or all of: (a) a characteristic of an occupant of the vehicle (e.g., name, account number, address, etc.); (b) a characteristic of the vehicle (e.g., make, model, year, class, registration number, marker number, odometer reading, owner, etc.); (c) a destination of the vehicle (entered through a data entry console and optionally stored within a vehicle memory); and (d) any other characteristic of interest.

Abstract: A battery capacity predicting method predicts a remaining capacity of a battery unit including a plurality of battery cells connected in series in an apparatus which uses the battery unit. The battery capacity predicting method includes the steps of comparing output voltages of each of the battery cells, and predicting the remaining capacity of the battery unit based on at least one of a minimum voltage and a maximum voltage out of the compared output voltages of the battery cells.

Abstract: A technique for detecting failed batteries while the battery is attached to one or more electronic devices and is receiving a float charge is disclosed. The float voltage minimizes the normal voltage differences between battery cells. The technique employs a ratio comparative analysis of cell voltages of a battery provided across the terminals of the battery. Application of the ratio comparative analysis in assessing the condition of a battery assumes an equal voltage drop across each battery cell such that the cells are modeled as a series of resisters with respect to the float voltage. Such equal voltage drop enables a comparative ratio analysis of the voltage across each of the two portions of the battery's cell stack to the voltage across the entire battery. The comparative ratio analysis determines a voltage threshold that identifies whether a battery has a shorted or open cell.

Abstract: Methods and apparatus are disclosed for inputting messages and other infotion, such as advertisements, to a vehicle while the vehicle is coupled to a local station, such as a recharging station or a refueling station. The messages can be selected in accordance with information received from the vehicle, including information that selectively identifies one, some, or all of: (a) a characteristic of an occupant of the vehicle (e.g., name, account number, address, etc.); (b) a characteristic of the vehicle (e.g., make, model, year, class, registration number, marker number, odometer reading, owner, etc.); (c) a destination of the vehicle (entered through a data entry console and optionally stored within a vehicle memory); and (d) any other characteristic of interest.

Abstract: A battery tub tester is disclosed that tests the individual batteries, battery accessories and connections as they are being assembled into a battery tub for an electric vehicle. The batteries and battery tub accessories, including temperature sensing devices and battery monitor modules, are mounted and electrically connected in the battery tub in accordance with a known battery tub assembly scheme. As the assembler mounts and connects the batteries and battery tub accessories, the tub tester determines the battery voltages of each battery after it is mounted and connected within the tub to determine if the batteries have the desirable voltage and will operate as they are intended and are connected properly. Additionally, the tester determines the temperature readings as the temperature sensors are being mounted, to determine if the temperature sensors will operate as intended and are connected properly.

Abstract: This disclosure sets out a multiple battery tester having a tray loaded with a set of batteries. The tray is placed in a receptacle and end located terminals move vertically to clamp a battery. The contacts bear on the battery, establishing a current flow path. This loop connects in charge/discharge system for testing. Test routines can be varied and data is recorded over time.

Abstract: Instability and oscillation are avoided in an overcharge/overdischarge control circuit by providing comparators with sufficient gain to minimize leakage current penetration into control circuitry when an output of a comparator used for comparing the output voltage of a secondary cell with a reference voltage is at an intermediate level. An overcharging/overdischarging detection circuit with two secondary cells connected in series has voltage dividing resistors connected in parallel therewith for producing a divided output voltage for each secondary cell, the divided output voltages each being supplied to a respective comparator. A first comparator has an input stage comprising N-channel MOS devices. A second comparator has an input stage comprising P-channel MOS devices.

Abstract: A cell evaluating method for evaluating characteristics of a secondary cell which can be repeatedly charged and which includes a step of detecting a cell voltage after a predetermined first charge operation for the cell is started, a step of, if the detected cell voltage is smaller than a reference voltage, proceeding to a second charge operation different from the predetermined first charge operation, and a step of evaluating a state of the cell. Moreover, the cell evaluating method includes a step of carrying out a first cell voltage detection after a first predetermined period of time has passed since a halt of the charge or discharge of a cell, a step of carrying out a second cell voltage detection after a second predetermined period of time has passed, and a step of evaluating, if the difference between the results of the first and second detections is not smaller than a predetermined value, that an internal short circuit occurs in the cell.

Abstract: A device for testing a battery includes circuitry adapted to measure a first conductance of a first portion of a string of cells that makes up the battery. Further circuitry is adapted to measure a second conductance of a second portion of the string of cells that makes up the battery. Comparison circuitry compares the first conductance and the second conductance and provides an output based upon the comparison which is related to a condition of the battery.

Abstract: A circuit and method are presented for making differential voltage measurements when one or both measurement points are at voltages that exceed those allowed by a typical differential amplifier, and is particular useful for monitoring the individual cell voltages of a number of series-connected cells that make up a rechargeable battery in which some cell voltages must be measured in the presence of a high common mode voltage. Each measurement point is connected to an input of a respective voltage divider, with all the divider outputs connected to a multiplexer having two outputs. The two multiplexer outputs are connected to a differential amplifier. When the voltage dividers are "closely matched," the output of the differential amplifier is directly proportional to the differential voltage between the pair of points to which the dividers are connected, and the differential voltage between those two points is accurately determined.

Abstract: A battery-cell protection system includes a processor, a wake-up circuit, and a shunt or isolation switch. The processor responds to voltages from cells in a battery by detecting any of the voltages being less than or equal to a predetermined threshold voltage. The processor samples cell voltages at a fast sampling rate and compares the sampled voltages to a predetermined threshold value. The processor further identifies any cell having an associated voltage that is less than or equal to the predetermined threshold voltage. The wake-up circuit responds to a current load from the battery by activating the processor. The shunt switch responds to the identification of the cell by selectively electrically shunting the identified cell to allow the other cells of the battery to continue to supply power to a connected load. The monitoring and identification of cells are performed in parallel to rapidly monitor all of the cells at once.

Abstract: A method of testing the electrical capacity of a plurality of secondary batteries connected to a load. The battery testing method reduces the time during which the entire electrical capacity of the secondary batteries remains low. In the case of secondary batteries which are made up of a nickel cadmium battery cell, the testing method prevents a memory effect from arising in the batteries. Using the battery testing method, the secondary battery is forcibly discharged, whereby the characteristics of the battery resulting from the discharge are tested. During the test, the secondary battery to be tested is discharged when the other secondary batteries are charged to saturation. In the case of the nickel cadmium secondary batteries, the batteries are fully discharged. The electrical capacity of the secondary battery is checked by measuring the time that elapses before the secondary battery has completely discharged.

Abstract: In a battery-driven portable computer, a battery pack is constituted by m battery sets connected in series each including n lithium-ion secondary battery cells connected in parallel. A voltage monitor for monitoring the voltage of the terminal electrode of each battery set and a charger for independently appropriately charging each battery set in accordance with a monitor result are arranged, thereby realizing battery driving by a lithium-ion secondary battery pack having a large capacity.

Abstract: Connections between batteries and impedance measuring circuitry in a system for on-line measurement of battery cell impedance is effected by twisted wire triplets.

Abstract: An apparatus and method for determining a location and resistance of an electrical leak in a battery having a first and second terminals. The apparatus includes a resistor, a switch assembly for selectively connecting the resistor to the first terminal of the battery and for selectively connecting the resistor to the second terminal of the battery, and a controller.

Abstract: A battery monitor for monitoring the voltage and temperature of the batteries associated with a battery pack of an electric vehicle. The battery monitor includes an opto-isolator that electrically separates an isolated portion of the battery monitor connected to the batteries from a non-isolated portion of the battery monitor that transmits battery voltage and temperature signals to a vehicle controller of the electric vehicle. The battery monitor is positioned proximate to a battery tub holding the batteries of the electric vehicle so that high voltage wires connected to the batteries within the battery tub are limited in length for safety purposes. Further, a limited number of wires transmitting the battery voltage and battery temperature signals from the battery monitor to the vehicle controller are required.

Abstract: A cordless device 11 comprises a load 13 and a multiple pack power supply 15 connected to load 13. A voltage detection circuit 23, 63, 64, 75, 76 is connected to supply 15 and detects when one of the batteries 17, 19 is charged and the other is discharged. Circuits 23, 63, 65, 75, 76 may also function as a voltage comparator circuit to identify when one of the batteries 17, 19 is defective. The detection or comparator circuit includes comparators 25, 33 for comparing the battery voltages. An indicator 41, 43, 65, 74, 81 is connected to the output of comparators 25, 33 and provides an end user identifiable signal responsive to the outputs of comparators 25, 33.

Abstract: For measuring a temperature with a thermistor, an electrical circuit including the thermistor and resistors for voltage division has to be maintained in the normally energized state and a variation in the voltage caused by resistance variation is detected. This requires a considerable amount of power consumption. On the other hand, thermal reed switches SW1 to SWn are mounted on the surfaces of the unit cells 1-1 to 1-n included in the battery pack 10. Each of the thermal reed switches is connected at one end to a common power source VDD and at the other end to a corresponding input terminal of a selector switch 20. The selector switch 20 is responsive to a switch signal from a determining unit 30a for passing selectively and periodically input signals of the input terminals to the determining unit 30a which in turn detects the temperature of a corresponding unit cell on the basis of the input signal selected by the switch signal.

Abstract: The present invention provides a method for detecting an electrical conductivity leakage path in a vehicle having a plurality of batteries coupled in series and having a chassis ground. The method comprises the step of (a) providing a voltage divider for each of the batteries, each voltage divider having an output having a voltage at a potential between the potentials of the positive and negative terminals of the voltage divider's respective battery. The method also includes the step of (b) providing a plurality of electrical connections, each switchable between open and closed, each between a voltage divider output and chassis ground. Furthermore, the method comprises the steps of (c) closing the switchable electrical connection between the first voltage divider output and chassis ground.

Abstract: A device for measuring the cell parameters of an entire storage battery having several series-connecter cells. A non-linear circuit is connected between each electric connecting point of the cells and a common measurement point. The non-linear circuits have known current-voltage characteristics which can be varied by an element connected between the common measurement point and an end pole or a selected connecting point of the entire battery. The parameters of the individual cells can be determined from the electric variables established at the common measurement point, for different values of the element, and the corresponding operating points of the individual non-linear circuits, as defined by the known current-voltage characteristics.

Abstract: A battery-operated implantable medical device comprises a battery, a measuring device for determining the state of charge of the battery through measurement of the no-load voltage, and an electric load. The no-load voltage of the battery has an increased drop in a range in which a remaining residual energy suffices to keep the operation of the device going for a minimum period of time required to carry out a therapeutic process.

Abstract: In one embodiment of the present invention, a system is provided or measuring the voltages of the traction batteries of an electric vehicle. The system includes switches provided to switchably couple the batteries individually to an amplifier. The system also includes switches provided to assure that the same polarity is always provided to the amplifier; a single-ended amplifier can thus be used. The system includes an analog-to-digital converter coupled in communication with the output of the amplifier, and an optical coupler which couples the output of the analog-to-digital converter to the low-voltage portion of the electric vehicle's electrical system.

Abstract: A method of and apparatus for centrally monitoring the capacity of batteries in a battery string includes electrical leads connected to each battery terminal of the battery string. A capacity testing system a) switches between the electrical leads for sequentially selecting the leads associated with the terminals of each battery, b) measures the internal resistance of the battery associated with each selected pair of electrical leads, c) compares the internal resistance of each battery cell to an internal resistance threshold, and d) triggers an alarm when the internal resistance of a battery exceeds the internal resistance threshold.

Abstract: A continuously monitored battery operated power supply for maritime applications includes four batteries which form a parallel connected pair of banks in which the cells in each bank are series connected to each other. A Wheatstone bridge circuit connects a midpoint between the plurality of cells in the first bank of battery cells and a midpoint between the plurality of cells in the second bank of batteries. The circuit also includes a volt meter for indicating a voltage change due to the degeneration of a cell when the voltage change exceeds a predetermined value.

Abstract: A battery charger/monitor circuit for charging and/or monitoring a plurality of series-connected cells, including a voltage sensor for sensing the voltage across each of the cells to provide a high cell voltage signal proportional to the highest voltage across any of the cells and a low cell voltage signal proportional to the lowest voltage across any of the cells. The circuit is operable in a monitor mode or a charge mode. In the monitor mode, the cells are disconnected from a load if the low cell voltage signal decreases to a first predetermined level. The circuit includes a controller which provides a control signal in response to the high cell voltage signal, the low cell voltage signal and a current sense signal, for controlling the charging of the cells.

Abstract: A battery monitor for monitoring the voltage and temperature of the batteries associated with a battery pack of an electric vehicle. The battery monitor includes an opto-isolator that electrically separates an isolated portion of the battery monitor connected to the batteries from a non-isolated portion of the battery monitor that transmits battery voltage and temperature signals to a vehicle controller of the electric vehicle. The battery monitor is positioned proximate to a battery tub holding the batteries of the electric vehicle so that high voltage wires connected to the batteries within the battery tub are limited in length for safety purposes. Further, a limited number of wires transmitting the battery voltage and battery temperature signals from the battery monitor to the vehicle controller are required.

Abstract: The circuit has a common measurement transducer together with individual measurement interfaces for each of the cells. Each interface has its own generator for defining a measurement signal relating to a characteristic of the associated cell, and each of the interfaces has its own measurement signal output that is connected to the measurement transducer of the circuit via a common single-wire link. Each interface also includes two ports, operable in alternation so that one constitutes an input for control pulses transmitted to the interface while the other acts as an output for relaying such pulses after they have been received. Each interface also includes means for forcing a signal to be emitted via its measurement signal output to the measurement transducer of the circuit in the event of a threshold being crossed by a measurement element that monitors a characteristic of the cell with which the interface is associated.

Abstract: A multi-battery charging system for reduced fuel consumption and emissions for an automotive vehicle. The system starts the vehicle with a start battery in a fuel savings manner, removing electrical torque from the alternator shaft, and allows a second (run) battery to provide all or some of the current required by the vehicle loads as a fuel savings measure. The system also utilizes an electrically heated catalytic converter (EHC) and a third (EHC or storage) battery to provide a 3 to 15 second preheat and/or a 20 second current, during vehicle start, to the EHC heater coil, e.g., of a small EHC located in series with a standard catalytic converter for emissions reduction to reduce emissions during start. The start battery is recharged after start and switched out of the system fully charged for future vehicle starts.

Abstract: Disclosed is a series connection circuit for secondary batteries for preventing a reduction of energy usable as the builtup battery due to a difference of DOD of the batteries and a difference of voltage detection level of voltage detectors. The circuit includes voltage detectors for detecting the terminal voltage of the secondary batteries thereby to calculate the respective values of DOD thereof, transistors for discharging the secondary batteries independently, a charging unit to charge the secondary batteries and a controller for controlling the independent discharging operation of the transistors corresponding to the respective values of DOD. With the arrangement mentioned above, it is possible to equalize the values of DOD, whereby the reduction of usable energy caused by the increasing of difference of DOD can be prevented.

Abstract: A measurement circuit for a modular system of cells electrically connected in series, in particular for electrical accumulator batteries, includes individual interfaces respectively connected to each power terminal of a different cell and each including a single-wire measurement output for a current measurement signal to be transmitted to a common transducer via a common single-wire connection. The interfaces each incorporate a switchable measurement current generator. They are connected in series by successive elements of a single-wire connection enabling serial transmission of individual switching control pulses grouped into streams for the current generators.

Abstract: A method for detecting the condition of the individual cells of a bank of serially connected battery cells is provided. The method utilizes a single common sensing wire connected through respective non-linear component switching mechanisms to respective reference terminals. The reference terminals are located between adjacent batteries and at the end of the battery assembly. The method includes the step of detecting an instantaneous change of impedance at points of transition of the state of the individual switches provided.

Abstract: A system for monitoring aging of a battery comprising a plurality of cells connected in series and able to be fully discharged comprises a discharger which discharges one of the previously charged cells at a time to an end of discharge value. The quantity of electricity supplied by each discharged cell during discharging is measured. The quantity of electricity supplied by at least one discharged cell is processed to detect excessive aging of the battery. Excessive aging of the battery results in a residual capacity which is less than a fraction of the nominal capacity of the battery.

Abstract: This invention is a battery monitor and battery capacity indicator that uses a sense cell in addition to the main battery to determine main battery remaining capacity and depletion condition. A parameter of the sense cell is related to the main battery capacity so that the main battery will have a minimum capacity remaining when the sense cell parameter reaches a particular value or crosses a particular threshold. In a preferred embodiment, the sense cell is a battery which is identical and of the same manufacturing lot as the battery cell or cells in the main battery pack. A current is drawn from the sense cell that is larger than the current being drawn from the main battery. When the sense cell is fully depleted, the main battery will have a remaining capacity whose magnitude depends on the relationship between the main battery current and the sense cell current.

Abstract: Methods and apparatus are disclosed for inputting messages and other infotion, such as advertisements, to a vehicle while the vehicle is coupled to a local station, such as a recharging station or a refueling station. The messages can be selected in accordance with information received from the vehicle, including information that selectively identifies one, some, or all of: (a) a characteristic of an occupant of the vehicle (e.g., name, account number, address, etc.); (b) a characteristic of the vehicle (e.g., make, model, year, class, registration number, marker number, odometer reading, owner, etc.); (c) a destination of the vehicle (entered through a data entry console and optionally stored within a vehicle memory); and (d) any other characteristic of interest.

Abstract: A multi-battery charging system for reduced fuel consumption and emissions for an automotive vehicle. The system starts the vehicle with a start battery in a fuel saving manner, removing electrical torque from the alternator shaft, and allows a second (run) battery to provide all or some of the current required by the vehicle loads as a fuel savings measure. The start battery is recharged after start and switched out of the system fully charged for future vehicle starts. The run battery is recharged when its charge level drops below a predetermined level with an on board battery charging device powered from a 115 volt or 220 volt ac power line source external to the vehicle. The system also increases the alternator field current to charge the run battery during vehicle deceleration to use vehicle momentum to torque the alternator shaft, thus saving fuel. The system controls the alternator field current with a voltage regulator.

Abstract: A method of testing characteristics of battery set includes a multicircuit voltage tester having a plurality of voltage testing line sets, which are coupled respectively with a positive terminal and a negative terminal of a battery unit of the battery set, which is subsequently permitted to discharge to a load for a predetermined period of time and which is subsequently recharged. During such times when the discharging and the recharging of the battery set are under way, the multicircuit voltage tester is capable of scanning, reading and writing repeatedly the voltage data of each battery unit. Such data are stored in a memory and are plotted equidistantly to form a chart comparing the voltage characteristics of the battery set. The characteristics of each battery unit can be determined by observing the change in space between the characteristic curves in the chart.

Abstract: A reserve time predictive system for predicting the capacity of a discharging battery monitors the instant voltage of a battery, its discharge rate and a slope of the voltage vs ampere-hours removed from the battery. The discharge profile of battery voltage vs ampere-hours removed, and the difference between the present and end voltage and the slope of voltage vs ampere-hours remaining is utilized to determine a prediction of reserve time remaining until the battery discharges to the specified end voltage. A combination of remaining reserve time and the measurement of capacity removed also determines the available capacity of the battery from a fully charged state. This information is used as historical data for use in subsequent predictions of battery capacity.

Abstract: Defective battery cells are detected by individually monitoring the voltage utput therefrom, which characteristically becomes abnormal when the defective condition occurs. Each cell is independently referenced to a common ground by its voltage monitoring device which drives a level sensing comparator that generates a control signal when the output voltage from that cell becomes abnormal. This control signal drives at least one switch to indicate when the defective condition occurs.

Abstract: Impedance measurement of battery cells within a battery system comprising at least one string of battery cells is accomplished by dividing each of the strings into at least two portions. A loading current for measurement purposes is only imposed on a portion of one of the strings at any given time and battery cell voltage measurements are made only within this string portion.

Abstract: An apparatus and method for locating and electrically isolating failed cells in a network of cells is disclosed. The apparatus includes a device for sampling voltage and current levels of each of the cells of the battery. Another device compares the sampled voltage and current levels to voltage and current limits to determine whether a cell has failed. If a cell has failed, control circuitry produces an activation signal which is conveyed to a switch associated with the failed cell. The activation signal drives a heating element of the switch. The heating element, which surrounds a fusible link of the switch, melts the fusible link. The fused link congregates at the base of the switch. In the case of a parallel network of cells, the fused link forms an open circuit, while in the case of a series network of cells, the fused link forms a bypass circuit. Consequently, the switch isolates the failed cell from the good cells remaining in the battery.

Abstract: An apparatus for measuring charge state of a battery having multiple cells includes a transmitter that is connected to the battery to apply a test signal across the battery. This test signal is preferably a continuous square wave signal having a frequency less than 3 Hz. The test signal alternates between a voltage adequate to charge the battery and a lower voltage, and the charging voltage is retained for a time sufficient to allow a polarization voltage to develop across individual cells. A receiver is connected to the cell to monitor the polarization voltage across a cell as it develops in response to the test signal. This polarization voltage can be monitored for example using a DC voltmeter, or by displaying the voltage versus time waveform. In either case an accurate indication of the state of the charge of the cell is provided.

Abstract: A charging station for electric vehicles which have rechargeable batteries is provided. The charging station comprises a power section controlled by a fast acting power controller, a power connector and associated power cables for connecting to the vehicle, an interface with signal cables to carry status and/or control signals between the vehicle and the power controller, and a lockout which precludes delivery of power to the vehicle except when the power connector is in place. High charging currents are delivered to the battery of the vehicle as a consequence of signals at any instant in time to the power controller, so as to be able to turn delivery of the charging current on and off in less than a few milliseconds. The resistance free voltage of the vehicle battery is measured during intervals when the charging current is off, and the operation of the power controller is a function of the battery resistance free voltage at any instant in time.

Abstract: Disclosed is a battery condition monitoring system that monitors the condition of batteries connected in parallel in order to determine that each battery is generating the necessary power. The system determines the difference in voltages that are proportional to the currents generated by the batteries. The system compares the voltage difference between the currents that is a positive value to a predetermined reference voltage which is the maximum allowed difference in the battery currents. If the positive difference value is greater than the reference voltage, one or more LEDs will illuminate indicating that one or more of the batteries is weak or defective, uniquely identifying the battery or batteries.

Abstract: A method and apparatus for monitoring the performance of fuel cells arranged in series. More particularly, the method and apparatus involve the measurement and comparison of fuel cell performance indicators, such as voltage, in groups of cells connected in series. In a first embodiment, the voltage across each fuel cell group is compared to a reference voltage equal to a predetermined minimum voltage. In a second embodiment, the voltage across each group is compared to a reference voltage equal to the average across all fuel cell groups. In a third embodiment, a reference voltage equal to the voltage across one group is compared to the voltage across each of the other fuel cell groups. In a fourth embodiment, the voltage across each group is compared as a reference voltage to the voltage across an adjacent fuel cell group. Other embodiments comprising various combinations of the first, second, third and fourth embodiments are also provided.

Abstract: A simple and inexpensive battery capacity monitor which indicates the remaining capacity of a battery by indirect measurement of the equivalent internal resistance. The monitor momentarily applies an RC load across the battery terminals and indicates the peak capacitive charge which is indicative of the equivalent internal resistance, which in turn can be correlated to the remaining battery capacity.

Abstract: A measurement system for measuring discrete voltages of serially connected battery modules making up a battery power supply wherein there would be connected to each junction between cells one terminal of a dual-level voltage responsive switch and wherein the other terminal of each switch is connected to a common terminal. The switches are identical, and each would close at a first voltage across it and open at a second, slight higher, voltage. A ramp voltage is generated and connected from the common terminal and the high voltage terminal of the supply. The ramp voltage and current through this circuit are concurrently measured and displayed wherein the difference in voltage between the appearance of two current pulses is illustrative of the battery voltage of the battery module connected between switches giving rise to the current pulses.

Abstract: An automatic monitoring system of storage batteries housed in battery rooms comprises an acquisition satellite associated with a sensor to measure various physical parameters representative of the operating state of a pilot battery cell, notably the density, temperature and electrolyte level, a data concentrator located outside the corresponding battery room and arranged to communicate by radioelectric waves with the acquisition satellite, and a centralized processing unit connected to the concentrator by a two-way cabled communication network.

Abstract: Apparatus for measuring the total internal resistance of a multicell battery having positive and negative terminals employs a first transistor device having an input and an output and having mutually exclusive conductive and non-conductive electric states. An arrangement of resistances is connected in series with the device to form a network. The network is connected between the positive and negative terminals. An operational amplifier has an output connected to the input of the device and first and second inputs. The first input is connected to the network at a point connected to both of the device and the arrangement. A square wave signal alternating between a positive voltage and ground on alternate half cycles is applied to the second input. The device is in the conductive state when the alternating voltage is positive and is in the non-conductive state when the alternating voltage is at ground.

Abstract: The non-intrusive open battery bank detector circuit senses an alternating current component of the DC trickle charge carried by one of a pair of cables connected between the battery charger and the bank of batteries. The detector circuit includes a sensor that is disposed adjacent, but not physically around or electrically connected to, one of the cables. The sensor detects magnetic fields established around the cable. The output of the sensor is connected to a low-pass filter which passes signals consisting primarily of 60 and 120 hertz components. A pre-amplifier amplifies the passed signals. A ripple filter smoothes the pre-amplified signals and a comparator determines whether the smoothed signal is greater than a reference signal thereby signifying the presence of a DC trickle charge on the cable next to the sensor. A transistor switch has its control input connected to the output of the comparator and is triggered on when the output of the comparator is high.