Showing papers on "State of charge published in 1995"

Bidirectional current pump for battery charge balancing

Abstract: A battery balancing system for balancing charge among series connected batteries. The battery balancing system includes a series connected battery array having a predetermined number of series connected batteries. A predetermined number of bidirectional charge balancing modules are provided and each respective module is coupled across two consecutive batteries. A controller is connected to each of the batteries for sensing the state of charge of each of the batteries and for providing control output signals that turn on and off and control the current direction flow of the modules to balance charge among batteries. Each module includes first and second series connected switches coupled across two consecutive batteries. Each of the series connected switches have control inputs connected to control outputs of the controller. First and second diodes are respectively coupled across the first and second series connected switches. An inductor is coupled from a point between the first and second series connected switches and a point between the batteries.

Device and method for measuring the charge state of a nickel-cadmium accumulator

Abstract: The battery (3), which powers an apparatus (2), supplies an auxiliary circuit for a short time (5). A test and control component (6) of the device superimposes a low amplitude current interference Δi onto the discharge current (1). The interference signal frequency f is chosen acccording to the capacity and the discharge current of the battery (3). Processing of the frequency response of the battery (3) by the test and control component provides an indication of the combined impedence of the battery at that frequency. The value Z I =(ΔV/ΔI) sin (Δφ) of the imaginary part of the impedence so measured, or advantageously the value of the quantity Γ=Z I -2 f -3/2 thereby indicates the state of charge of the battery.

Method of controlling generated power in series hybrid vehicle

Abstract: A method of controlling a generated power in a series hybrid vehicle. From the tendency of an inverter input power or a motor dissipation power in a certain period is first estimated the tendency of the inverter input power or the motor dissipation power in the next period. The target power to be generated is then set on the basis of the results of the estimation. Alternatively the target power to be generated is corrected in accordance with the quantities such as an accelerator angle indicating the load of the motor or a battery current indicating the state of charge/discharge of the battery. Alternatively that period is compulsorily interrupted to start the next period. This will eliminate a delay arising from averaging the inverter input powers or the motor dissipation powers for use as the target power in the next period, thus resulting in improved vehicle power efficiency and drive feeling.

Generator controller used in hybrid electric vehicle

Abstract: The battery current is sampled and accumulated for T seconds (102,104). The obtained accumulated value is used to determine the control target Pg of the generated power. Since the generated power is controlled according to the accumulated current of the battery which fits the characteristic of the battery (14) compared to the charged-and-discharged power, state of charge (SOC) of the battery (14) can be more accurately controlled within the target zone. When the SOC of the battery (14) is initially outside the target zone (116), the SOC is adjusted within the target zone by forcibly discharging (112) or charging (118) the battery (14). The precision of SOC control can be improved compared to when the SOC of the battery (14) is controlled using the charged-and-discharged power.

Resettable state-of-charge indicator for rechargeable batteries

Abstract: An improved state-of-charge indicator for a battery wherein the counter cuit of the battery state-of-charge indicator includes a means for both resetting and fine-tuning the counter circuit. The current flowing from the monitored battery is passed through a sensing resistor. The voltage across the resistor is amplified and integrated over time and the result of the integration is stored in a capacitor discharged by a switch whenever a threshold voltage is achieved. The cycle is repeated each time coulomb of capacity is removed from the battery. The counter circuit counts the charge/discharge cycles of the capacitor resulting in a count representative of the amount of energy dissipated and therefore indirectly of the amount of energy remaining in the battery system. In this improvement, both a resetting means and a fine-tuning means are included for the counter circuit when the battery is being recharged. The fine tuning means can be preset to reset the counter circuit upon reaching a predetermined voltage signifying that the battery is fully charged. The fine-tuning means may further comprise a zener diode used with a MOSFET mixer.

Effect of state of charge on impedance spectrum of sealed cells Part II: Lead acid batteries

Abstract: Alternating current impedance spectroscopy (ACIS) was performed on commercial sealed lead acid batteries. A method previously developed in the literature was modified to determine the state of charge of sealed lead acid cells by obtaining the impedance spectrum in a wide frequency range. The data were sensitive to state of charge at low frequencies. A modified Randles' circuit was used to fit the impedance data. The effect of the state of charge on the equivalent circuit parameters was determined.

Controller of an engine driven generator for an electric vehicle

Abstract: Controller 40 receives accelerator opening and brake depressing amounts, and the output of an ammeter 30 and voltmeter 32 as inputs. In response to the state of these input signals, the controller 40 determines the timing to detect the state of charge (SOC) of the battery 10 and detects the SOC of the battery 10. That is, it is first judged that the SOC is not more than a predetermined value if the voltage of the battery 10 is not more than a predetermined value when the accelerator opening is not more than a predetermined value. It is next judged that the SOC is not more than a predetermined value if the voltage of the battery 10 is not more than a predetermined value when the brake is depressed beyond a certain degree. In these cases, the engine 24 is driven to cause a generator 22 to perform generation of electricity to charge the battery 10.

Charge measurement circuit for a battery in which oscillators are used to indicate mode of operation

Abstract: A battery pack (10) has a charge measurement circuit (12) for estimating the state of charge during use. The charge measurement circuit (12) includes a sense resistor (24), amplifier (26), at least one oscillator (28), counter (30), and a communications circuit (32). The battery pack powers a host device (16), which has a limited number of modes of operation, each mode requiring a different current level. The number of oscillators (28) equals the number of modes of operation of the host device (16). As current is drawn from the battery cells (18), the sense resistor (24) and amplifier (26) act to convert the current to a voltage level. The voltage level is fed to each oscillator (28) present. Each oscillator (28) provides a clock signal at a frequency corresponding to one mode of operation of the host device, and is activated when the voltage level is within a preselected range. The clock signal is fed to a counter (30), which counts at a rate determined by the frequency of the active oscillator (28). The host device (16) can request the current count value from communications circuit (30) to estimate the state of charge of the battery cells (18).

Dual battery system control circuit

Abstract: Dual batteries having a CRAnking battery and an AUXiliary battery require a switch to the alternator and to disconnect the auxiliaries before the battery becomes depleted. The switch measures the AUXiliary battery's state of charge during alternator charging. The switch opens to prevent overcharging and to preserve the CRAnking battery charge while allowing the AUXiliary battery to discharge preferentially. The switch instructs the alternator to select a burst, float or top up charging voltage depending on the AUXiliary battery state of charge. The switch uses microprocessor control. This utilizes tables to interpret circuit values. A 3-axis graph relates discharge current and voltage with state of charge.

VRLA battery monitoring using conductance technology

Abstract: A new method of monitoring the conductance of valve-regulated lead-acid batteries while in service is introduced, showing the effective use of relative conductance measurements to detect capacity loss, reduced state of charge, and the onset of thermal runaway

Method and apparatus for measuring the state of charge in a battery based on volume of battery components

Abstract: The state of charge of electrochemical batteries of different kinds is determined by measuring the incremental change in the total volume of the reactive masses in the battery. The invention is based on the principle that all electrochemical batteries, either primary or secondary (rechargeable), produce electricity through a chemical reaction with at least one electrode, and the chemical reactions produce certain changes in the composition and density of the electrode. The reactive masses of the electrodes, the electrolyte, and any separator or spacers are usually contained inside a battery casing of a certain volume. As the battery is used, or recharged, the specific volume of at least one of the electrode masses will change and, since the masses of the materials do not change considerably, the total volume occupied by at least one of the electrodes will change. These volume changes may be measured in many different ways and related to the state of charge in the battery. In one embodiment, the volume change can be measured by monitoring the small changes in one of the principal dimensions of the battery casing as it expands or shrinks to accommodate the combined volumes of its components.

Method for determining the remaining capacity of a lead acid battery and device using this method.

Abstract: of EP0391106To determine the respective state of charge of a lead acid battery under changing load, introducing reference values, a reference line is created as a measurement reference value from which a DELTA U value, determined on connection of a load, is subtracted and this reference line is accordingly shifted to a new present load reference line which is correspondingly matched to a newly determined DELTA U value when the load changes. The reference line is experimentally determined by removing a load from the loaded battery and determining the value which occurs within a short time after removing the load. The device for carrying out the method contains an A/D converter, a microprocessor system and a bar-type display.

External measurement system for checking battery charge state

Abstract: The system for contactless measurement of the state of charge of an electric accumulator (100) is based on the existence of at least one electrode within the accumulator (110) which has a conductivity which varies as a function of the state of charge The system includes a measurement circuit (140) including a coil (120) situated near to the accumulator, with further components for determining the complex impedance of the measurement circuit The measurement circuit includes an LCR circuit with a generator (130) applying a periodic excitation, and a frequency response analyser providing an output with a component related to the complex impedance This signal is relayed to a display (162) Both the modulus and the phase of the complex impedance are determined as part of the measurement

Circuit for measuring the state of charge of an electrochemical cell

Abstract: The invention relates to a circuit for measuring the state of charge of an electrochemical cell that includes a parasitic resistance. The circuit comprises: means for subjecting the electrochemical cell to a reference voltage less than its nominal voltage, so as to cause it to deliver a discharge current; means for measuring the discharge current and providing an indication of the state of charge of the electrochemical cell; and correction means for correcting the reference voltage as a function of the discharge current, the correction means providing a corrected reference voltage that compensates for the parasitic resistance.

Attachment for vehicle starter battery

Abstract: To recognise the actual state of charge for a car battery, there is an accessory that is plugged into a special socket on it The accessory is a cast plastic housing containing an electronic chip, acting as a voltage detector, combined with an acoustic alarm At the end of a certain time period, starting when the starter motor is first actuated, the actual battery voltage is compared with a threshold The voltage difference is converted into an audible alarm of a frequency which depends on the magnitude of the voltage difference If the engine fires before the time period is finished, no signal is given

Battery charge indicators

Abstract: A low-cost battery charge indicator is provided which is capable of indicating a quantity of charge upon a battery or battery pack. The charge indicator includes positive and negative battery terminals and a charge gauge circuit mounted within a battery pack or a battery-powered electronic device. The positive and negative terminals are adapted to receive a battery and to test the battery charge within the battery during times in which the charge gauge circuit is active. Activation of the charge gauge circuit occurs by depressing a momentary switch coupled between the charge gauge circuit and the battery terminals. Upon activation of the switch, one of three LEDs will emit light informing the user of the state of charge upon the battery or battery pack. The switch remains normally open to avoid current draw from the battery during non-test times.

Battery recharging system with state of charge detection to prevent overcharging

Abstract: A state of charge test is first performed on the battery by applying a current pulse 102 and then observing the voltage decay characteristics 112, 116, 118, 120 which result. Batteries which are initially nearly fully charged exhibit a larger voltage decay than batteries which are not as fully charged. The result of this initial state of charge test is used to determine how to best terminate battery charging. In this way battery overcharging is prevented regardless of the initial state of charge of the battery.

A Practical Application of the Pb/PbO2 Cell: The Determination of the State of Charge of Lead-Acid Batteries

Abstract: A laboratory-made device to estimate the available charge of lead-acid batteries is proposed. It is based on a Pb/PbO2 potentiometric cell which potential is directly proportional to the electrolyte density which in turn, is related to the available capacity of the battery. Standard deviations less than 0.5% were obtained in relation to the traditional density measurements.

Time-sharing charge equalization for series connected battery strings

Abstract: This study proposes the time-sharing charge equalization having an independent charge rate for each of the battery, which is dependent on nonuni-formities in state of charge. During one equalization charge cycle, only one battery is charged through the switch bank which are connected to AC-to-DC conveter with low rating vol­tage and current. And the next charge cycle, the equalizer charges the another battery cosequently.

Testing and evaluation of tubular positive lead-acid batteries

Abstract: The possibility of using lead-acid batteries in tandem with fuel cells in applications such as submarine propulsion require a strong understanding of the transient behaviour of the lead-acid battery. One simple yet accurate method of describing the response at a given state-of-charge is as a resistor-capacitor model. Preliminary testing supports the model's ability to describe the voltage response to load changes at a given state-of-charge. Furthermore, analysis of the steady state characteristics of the cells supports claims in the literature that the charge transfer resistance is partially a function of the inverse of the current. Once complete, the empirical relationship describing the circuit elements will be a useful tool to monitor the gassing effects during pulse charging. >

Mathematical modeling of the nickel/metal hydride battery system

Abstract: A group of compounds referred to as metal hydrides, when used as electrode materials, is a less toxic alternative to the cadmium hydroxide electrode found in nickel/cadmium secondary battery systems. For this and other reasons, the nickel/metal hydride battery system is becoming a popular rechargeable battery for electric vehicle and consumer electronics applications. A model of this battery system is presented. Specifically the metal hydride material, LaNi{sub 5}H{sub 6}, is chosen for investigation due to the wealth of information available in the literature on this compound. The model results are compared to experiments found in the literature. Fundamental analyses as well as engineering optimizations are performed from the results of the battery model. In order to examine diffusion limitations in the nickel oxide electrode, a ``pseudo 2-D model`` is developed. This model allows for the theoretical examination of the effects of a diffusion coefficient that is a function of the state of charge of the active material. It is found using present data from the literature that diffusion in the solid phase is usually not an important limitation in the nickel oxide electrode. This finding is contrary to the conclusions reached by other authors. Although diffusion in the nickel oxide active material is treated rigorously with the pseudo 2-D model, a general methodology is presented for determining the best constant diffusion coefficient to use in a standard one-dimensional battery model. The diffusion coefficients determined by this method are shown to be able to partially capture the behavior that results from a diffusion coefficient that varies with the state of charge of the active material.

Optimizing the size of photovoltaic/wind hybrid generating system controlled by fuzzy inference

Abstract: The photovoltaic/wind hybrid generating system is analyzed through simulation, and the comparison between the proportional control method (the conventional method) and the fuzzy control method which is proposed in this paper is performed. The results show that the utilization of fuzzy control method, comparing the proportional method, can cut down the energy surplus in nearly half, so that renewable energy can be used effectively. Furthermore, change of the state of charge (SOC) can be controlled, so it becomes favorable for the protection of the storage battery. From these things, thus, it is understood that the capacity of the storage battery can be reduced compared to the conventional method. And this study also shows the method calculates the optimal structure ratio of PV array/wind turbines from electrical load data and weather data.

Battery model for the Extreme Ultraviolet Explorer Spacecraft

Abstract: This paper describes a battery model that has been developed to predict whether the Extreme Ultraviolet Explorer spacecraft batteries will support proposed loads for user-specified time periods (usually about 2 weeks). For given orbit, attitude, solar array panel, spacecraft load, and time period, the model is able to calculate minute-by-minute values for the net power available for charging the batteries plus minute-by-minute values for the voltage, current, and state of charge. The model's calculations are explained for the beginning-of-charge, constant-voltage charging, and discharge phases. A comparison of predicted values with telemetry data shows good correlation. The model can be adapted to changing spacecraft conditions through the use of empirical data from ground tests and telemetry, and the model can be customized for other spacecraft.

Nickel-hydrogen battery state of charge management in the absence of active cooling

Abstract: Battery management during prelaunch activities has always required special attention and careful planning. `ne transition from nickel-cadmium to nickel-hydrogen batteries, with their higher self discharge rate and lower charge efficiency, as well as longer prelaunch scenarios, have made this aspect of spacecraft management even more challenging. The NASA AXAF-I Program requires high battery state of charge at launch. The use of active cooling, to ensure adequate state of charge during prelaunch charge, trickle charge, and stand was considered and proved to be expensive and difficult to implement. Alternate approaches were considered. A procedure including optimized charging and low rate (

Method and apparatus for non-contact electronic control of waterflow in a sanitary installation

Abstract: Water supply valves for use in sanitary installations are controlled electronically by microprocessor based units that are battery powered. The reliability of the system is dependent upon the condition and state of charge of the battery and a number of status conditions are indicated. During installation when a new battery is used a single LED operates in a blinking mode. This mode is also used to signal that either a loaded or unloaded battery is down to 10 percent reserve power level. Continuous lighting signals inadequate power and with the LED inactive the battery condition is in order.