Showing papers on "State of charge published in 1987"

Battery charge state monitor

Abstract: A battery charge state monitor has a charging circuit (40) for charging nickel cadmium cells. An integrating (80) generates a saw-tooth waveform during charging and discharging of the cells, the frequency of which is proportional to the rate of charging and discharging of the cells. The saw-tooth waveform is converted into a train of pulses by a pulse shaping circuit (120), the pulses being counted by a counter (140). During initial calibration, the number of pulses generated for an exact known quantity of charge is stored in a microprocessor (160). During subsequent use and charging of the cells, the counter (140) counts in one direction during charging and in the opposite direction during discharge. Since the frequency of pulses generated during charging and discharging is exactly proportional to the rate of charging and discharging the count of the counter (140) provides an exact indication of the state of charge of the cells.

Method for detecting the state of charge of a battery

Abstract: To detect the respective state of charge of a battery, used, for example, for feeding an electrical vehicle drive motor, in a simple manner with little hardware expenditure, the battery voltage (U) is only measured when a predetermined value of the discharge current of the battery is present, the measurement value (B) is compared with a stored nominal discharge curve (a) for normal conditions and the state of charge allocated to it in accordance with this curve is indicated (Fig. 2).

Automotive electric storage battery power system

Abstract: An automotive electric storage battery 2 of secondary type in situ in a motor vehicle is connected to the electric components 4 of the vehicle and connected in parallel with a primary battery 6 of higher voltage (e.g. 18 volts) with the interposition of an electric resistance 12 and a diode 10 which prevents current flowing from the electrical components of the vehicle, e.g. the alternator, through the primary battery. The state of charge of the secondary battery 2 is substantially maintained for an extended period of time because, when the vehicle engine is not running, the primary battery 6 supplies a substantial portion (e.g. initially 90 per cent or more) of the residual electrical demand of components which are partly or wholly energised at all times, such as a clock and a computer. The arrangement is of particular use when a vehicle is exported, since the secondary battery 2 will still be able to start the engine on arrival at the destination, whereat the primary battery 6 may be discarded. The battery 6 may be coupled to battery 2 via the cigarette lighter socket in the vehicle.

Sizing Batteries for Photovoltaic Systems

Abstract: This paper describes a computerprogram for sizing photovoltaic stand-alone systems (PV-systems) with batteries. The computer program is based on an insolation model described by M Collares-Pereira and Ari Rabl (1) and a newly developed battery algorithm. The algorithm is based on - capacity derating as a function of electrolyte temperature - charging efficiency as a function of electrolyte temperature and state of charge - charging voltage as a function of electrolyte temperature and state of charge The program is used to calculate the required number of PV-modules and the size of the battery. The program was originally designed for nickel-cadmium batteries, but can also be used for sizing systems with lead acid batteries, if the required battery data are available.

Method and device for deciding state of charging of battery

Abstract: A method of determining the state of charge of a motor vehicle battery (1) in which a stabilization load (2) is applied to the battery (1) after the engine is switched off to accelerate the stabilization of the charge distribution within the battery (1). The stabilization load (2) is applied until the terminal voltage of the battery (1) reaches a level corresponding to a predicted value of the state of charge of the battery (1) After a pre-determined delay of 8 hours or less, the terminal voltage of the battery (1) is measured and the state of charge derived therefrom.

Instruments for monitoring the specific gravity of electrolyte in lead acid storage baiteries

Abstract: The change in the specific gravity of the sulphuric acid electrolyte in a lead acid storage battery serves to know the state of charge or the reserve capacity of the battery. Though the method of measuring the specific gravity using a float hydrometel is simple, it is cumbersome and time consuming when a large number of cells are involved. This paper reviews different approaches made by earlier workers and indicates the preliminary work carried out by the authors in this aspect.

Real time charge efficiency monitoring for nickel electrodes in NICD and NIH2 cells

Abstract: The charge efficiency of nickel-cadmium and nickel-hydrogen battery cells is critical in spacecraft applications for determining the amount of time required for a battery to reach a full state of charge. As the nickel-cadmium or nickel-hydrogen batteries approach about 90 percent state of charge, the charge efficiency begins to drop towards zero, making estimation of the total amount of stored charge uncertain. Charge efficiency estimates are typically based on prior history of available capacity following standardized conditions for charge and discharge. These methods work well as long as performance does not change significantly. A relatively simple method for determining charge efficiencies during real time operation for these battery cells would be a tremendous advantage. Such a method was explored and appears to be quite well suited for application to nickel-cadmium and nickel-hydrogen battery cells. The charge efficiency is monitored in real time, using only voltage measurements as inputs. With further evaluation such a method may provide a means to better manage charge control of batteries, particularly in systems where a high degree of autonomy or system intelligence is required.

Control system of charge

Abstract: PURPOSE: To control the state of charge by representing the residual capacity of a battery at the discrete value of a counting means and generating an alarm signal when the discrete value is brought to a value lower than a specified value. CONSTITUTION: A signal DCG representing a period during discharge and a signal CHG representing a period during charge are received by all input/output I/O41, and said each signal DCG, CHG is transmitted over a CPU 31. The residual capacity of a battery is shown artificially to the shape of the discrete value of a counting means such as an FF 45 from said respective signal DCG, CHG, and the residual capacity of the battery of a specified value or less is determined when the discrete value is lower than a fixed value. Accordingly, the residual capacity of the battery is controlled by the discrete value, thus improving facility, then also allowing the display of residual capacity. COPYRIGHT: (C)1988,JPO&Japio