Showing papers on "State of charge published in 1984"

Battery control and fault detection method

Abstract: This is a method for control, fault detection, fault isolation, and state-of-health monitoring of batteries and battery arrays. The method consists of measuring all of the battery, cell, or cell group voltages, using statistics to determine a means voltage and a standard deviation voltage, then comparing all of the measured voltages to the mean voltage. If the measured voltage deviates from the mean voltage by an arbitrary amount (number of standard deviations) corrective action can be implemented or an alarm signal given. The measurements need to be made rapidly enough to eliminate battery or cell voltage changes due to state of charge or temperature changes and, in most cases, require a computerized data collection/reduction system. Absolute high and/or low voltage limits can be included to prevent catastrophic events. The concept can be expanded to include similar temperature, pressure and/or battery current measurements in an array.

Method and apparatus for determining the state-of-charge of batteries particularly lithium batteries

Abstract: Method and apparatus for determining the state-of-charge of batteries, particularly lithium batteries, involves the steps of: (a) measuring the temperature of the battery; (b) loading the battery to produce a high discharge for a short period of time; (c) after a short rest period, measuring the open-circuit-voltage of the battery; and (d) determining from the measured temperature and open-circuit-voltage the residual state-of-charge of the battery. Preferably, the residual state-of-charge of the battery is determined by comparing the measured temperature and open-circuit-voltage with reference tables showing the state-of-charge at different temperatures and open-circuit-voltages for the respective battery.

Emergency battery cell monitor

Abstract: A wet cell battery monitor developed to monitor both electrolyte fluid level and electrolyte fluid charge (specific gravity) of a single cell. The monitor includes a probe and appropriate circuitry. The probe is adapted for insertion into a cell for monitoring and is connected to two circuits which are interconnected. Both include resistors, preferably variable, and include induction coil type relay switches. Blocking diodes are preferably used to maintain the independent integrity of each of the two circuit, one which warns of fluid level drop off and the other of a decrease in electrolyte fluid charge. The two circuits each drop off independenly in response to specific gravity (state of charge) and to fluid level, respectively, setting off alarms, e.g. visual or audio signals.

Nickel-oxygen monitor cell system

Abstract: A system for monitoring the state of charge of a nickel-alkaline secondary battery wherein the monitor cell is comprised of a sealed metal-gas cell having a nickel electrode and an oxygen counter-electrode.

Battery equalizer circuit

Abstract: A discharge circuit reduces the state of charge of a battery to a nominal zero so that the battery can be put through one or more complete charge/discharge cycles.

Motor vehicle electrical system

Abstract: (57) In a charge/float vehicle electrical system, heavy battery (12) charging is effected during periods of engine deceleration by engine deceleration responsive means (224) and the float voltage is adjusted by generator control means (220) so as to maintain the battery (12) state of charge at the level in existence at the initiation of the float mode

Electrochemical characteristics of the lithium/carbon monofluoride battery and its component half-cells

Abstract: The impedance spectrum of the Matsushita lithium/carbon monofluoride battery was studied extensively as a function of load, temperature, state of charge, and time after discharge. Resolution of the battery impedance spectrum into frequency domains characteristic of the electrolyte, the anode, and the cathode permitted the polarization and kinetic parameters of the individual battery electrodes to be measured. Most of the battery voltage loss is attributed to the carbon monofluoride cathode. Comparisons of the interfacial electrochemical properties of lithium half-cells in the battery electrolyte (1.0 mol dm−3 LiBF4/γ-butyrolactone) with those of thein situ battery anode show that the battery anode is coated with a film. Attempts to correlate the high-frequency (> 1 Hz) parameters of the battery impedance with state of charge proved unsuccessful.

Device and method of evaluating state of charge of battery and composite system using said method

Abstract: A combined battery state of charge evaluator and motor control system for an electric vehicle comprises a traction battery 10, a motor controller 14, a traction motor 11, a micro computer 16 and an interface circuit 15. The micro computer 16 receives signals representing battery temperature, total battery voltage, and battery current and calculates the charge withdrawn from the battery by integrating battery current and also calculates the remaining charge in the battery as a function of battery voltage. By summing the remaining charge and the charge withdrawn, the present charge storage capacity value of the battery is calculated. The micro computer 16 compares the present charge storage capacity value with a value representing 85% of the nominal charge storage capacity of the battery when new and selects the lower of these two values. The state of charge is then calculated as a function of the charge withdrawn and this lower value and displayed on a meter 34. When the remaining charge in the battery calculated by subtracting the charge withdrawn from this lower value falls below 6% of the battery capacity, the current supply to the motor 11 is limited to a predetermined percentage of the current demanded by the driver. This predetermined percentage is progressively reduced as the remaining charge falls toward zero.

Sealed lead-acid batteries for solar applications

Abstract: Sandia National Laboratories is involved in the development of sealed lead-acid batteries capable of deep-discharge operation. This effort is an extension of existing technology employing an immobilized, starved electrolyte system with internal recombination of oxygen. Since watering is not required and there is no acid mist to cause external corrosion, the battery is maintenance-free. During contracts with Gould and Eagle-Picher, batteries were received quarterly and placed on test. With few exceptions, testing of these batteries has been completed. With proper charging, battery life averaged over 800 deep cycles. This was achieved with both the standard NEMA cycle test as well as a partial state of charge test. Charging voltages above 2.50 volts per cell appeared to be detrimental to the performance of the Gould batteries.

Hybrid PV Systems for the use of Total Solar Energy

Abstract: Studies have shown the advantages of the "solar-Diesel" hybrid systems compared to other models of fuel savers for telecommunication stations distant from commercial power lines. With a much smaller initial investment, practically the same reliability can be obtained as with 100 percent solar solutions. The idea is to put to use all the available energy of the sun with fewer solar panels (curve 2 on Fig. l), which may be called "Total Solar Energy System". Of course, it is necessary to maintain within the limits of a reliable operation the minimum state of charge of the battery. In practice this can be achieved by the use of a battery charger (Diesel-group or other) and a control system. The results are shown in two different diagrams, which can be used to make the project of hybrid solar systems. The formulas permit us to calculate, for a given site and system, all operational characteristics such as: - state of charge of the battery at the end of each month - monthly number of operation and operating time of the charging group - economy in fuel compared to 100% Diesel system Practical data and results in Brazil have proved the theory. (The above idea was first presented to the Commission of Alternative Energy Sources of Telebras in February 1981. It was partly published in Portuguese in the quarterly publication Revista Telebras in its September 1983 issue).

Battery charger and state of charge indicator. Final report

Abstract: The battery charger has a full-wave rectifier in series with a transformer isolated 20 kHz dc-dc converter with high frequency switches which are programmed to actively shape the input ac line current to be a mirror image of the ac line voltage The power circuit is capable of operating at 2 kW peak and 1 kW average power The BC/SCI has two major subsystems: (1) the battery charger power electronics with its controls; and (2) a microcomputer subsystem which is used to acquire battery terminal data and exercise the state-of-charge software programs The state-of-charge definition employed is the energy remaining in the battery when extracted at a 10 kW rate divided by the energy capacity of a fully charged new battery The battery charger circuit is an isolated boost converter operating at an internal frequency of 20 kHz The switches selected for the battery charger are the single most important item in determining its efficiency The combination of voltage and current requirements dictated the use of high power NPN Darlington switching transistors The power circuit topology developed is a three switch design utilizing a power FET on the center tap of the isolation transformer and the power Darlingtons on eachmore » of the two ends An analog control system is employed to accomplish active input current waveshaping as well as the necessary regulation« less

A Battery Charger and State of Charge Indicator

Abstract: A battery charger which has a full wave rectifier in series with a transformer isolated 20 kHz dc-dc converter with high frequency switches, which are programmed to actively shape the input dc line current to be a mirror image of the ac line voltage is discussed The power circuit operates at 2 kW peak and 1 kW average power The BC/SCI has two major subsystems: (1) the battery charger power electronics with its controls; and (2) a microcomputer subsystem which is used to acquire battery terminal data and exercise the state of charge software programs The state of charge definition employed is the energy remaining in the battery when extracted at a 10 kW rate divided by the energy capacity of a fully charged new battery The battery charger circuit is an isolated boost converter operating at an internal frequency of 20 kHz The switches selected for the battery charger are the single most important item in determining its efficiency The combination of voltage and current requirements dictate the use of high power NPN Darlington switching transistors The power circuit topology is a three switch design which utilizes a power FET on the center tap of the isolation transformer and the power Darlingtons on each of the two ends An analog control system is employed to accomplish active input current waveshaping as well as the necessary regulation

Performance characteristics of a battery charger and state-of-charge indicator

Abstract: A battery charge/state of charge indicator (BC/SCI) system for electric vehicle use was developed. The original and subsequent objectives for the BC/SCI and the rationale for those objectives are described. The requirements generated from the objectives are listed and a description of the BC/SCI is provided. The power section problem, the tests, and the test results are discussed.