SU547878A1 - Method for measuring the short-circuit resistance of a chemical current source - Google Patents

Description

one

The invention relates to chemical current sources and can be applied in determining the parameters of batteries and batteries.

Methods are known for measuring the internal resistance of a chemical current source by passing a constant or alternating current l through the test source.

Their disadvantage is low accuracy and significant loss of capacitance during the measurement.

There is also known a method for measuring the internal resistance of a chemical current source by measuring the voltage at the source, discharging it to a capacitor load, determining the voltage at that load, and calculating the measured parameter 2.

However, this method is unsuitable for measuring the internal resistances of high-capacity batteries with low-impedance load, since an adjusting resistor, shunt and emitter-collector switch commute to the triode, which are not low-impedance, in the battery discharge circuit.

The aim of the invention is to improve the accuracy and improve the loss of the chemical source of the TEC during the measurement.

This is achieved by the fact that in the process of discharging a test source to a capacitor load, they fix the change in voltage on it and build a curve of dependence of that voltage on time, choose any point on the section of this curve from the origin to the voltage value 0 , (where EHIT is the EMF of the chemical current source), the coordinates of this point are determined, and then the short-circuit resistance of the chemical current source is calculated on the basis of the HanpiS equation for the capacitor charge.

FIG. 1 shows an electrical circuit for measuring the short-circuit resistance of a chemical current source; ka fig. 2 - curve of voltage dependence of the capacitor charge U on time t

Claims (2)

The circuit includes key 1, a capacitor voltage recorder 2, a capacitor of known capacitance 3 and a tested chemical current source 4. The resistance of the current collectors, the Hbtx connector of the wires and the key in the closed state must be at least one order less than the measured short-circuit resistance . When a constant voltage is applied to a series-connected capacitor and the resistance (in this case, the internal resistance of a chemical current source), the voltage across the capacitor changes as follows: t and E e vs); (1) where B is the amplitude of the applied voltage or the emf of a chemical source of current; f is the internal resistance of the chemical current source; с - capacitor capacitance. The internal resistance of the source depends on the load resistance. With the closure of the key 1, the resistance of the capacitor 3 increases from zero to the resistance to leakage. In this case, the internal resistance of the source increases with the magnitude of the short-circuit resistance. If the internal resistance of the source did not change and was equal to the resistance of the short circuit, the expression (1) would take the form: (fc and Е (- | - e) (2) The difference between the expressions (1) and (2) increases by in the initial part of the curve with the accuracy of the method described, the following expression is valid: (3) The procedure for measuring the short-circuit resistance of a chemical current source is as follows: A discharge capacitor of known capacitance is connected to the test source and recorded using a recording device The curve for changing the voltage on the capacitor from time to time (Fig. 2). Choose a point on the plot of the recorded curve bounded by the origin point and the point with the voltage coordinate equal to eight tenths of the EMF value of the test source. k and, based on the expression (1), determine f gH, which with the accuracy of the described method is equal to the desired value of i. Obviously, the closer the selected point is to the origin, the smaller the difference between the EOS; to L / C Choose a point on the curve Uc Ct) on a piece where U. / E: O, 8 does not make sense because of the sharp decrease in the accuracy of the method in this area. Example. The measurement of the short-circuit resistance of nickel-cadmium alkaline batteries of type KH-10 is carried out. Copper busbars are used with a length of 30 cm and a cross section of 0.5 cm 7. Two capacitors of known capacitance K-50-6 with nominal values up to 4000 microfarads each are used as a capacitor of a known capacity. The recording device is a C-8-2 dual-beam storage oscilloscope; Key 1 is a switch with a closed state of resistance less than 0.00006 ohm. In the process of measuring the short-circuit resistance of the batteries, a point is selected on the time dependence of the voltage across the capacitor with a coordinate corresponding to L / C / E - 0.632. At the same time, the difference between (J does not exceed 0.7%, and the difference between exceeds 1%. At the same time, for batteries with different degrees of charging, short-circuit resistance values are in the range of 0.008 to 0.004 ohms. Invention Formula A method for measuring short-circuit resistance of a chemical source current by measuring the voltage at the source, discharging it to the capacitor load, determining the voltage at that load, and calculating the measured parameter, characterized in that, in order to improve accuracy and reduce losses, the bones of the chemical current source during measurement, during the discharge of the test source to the capacitor load, record the change in voltage on it and plot the time dependence of this voltage, then select any point on the section of this curve from the origin to the voltage value, equal to 0, where (-EMF of the chemical current source), determine the coordinates of this point, after which the short-circuit resistance of the chemical current source is calculated based on the capacitor charge voltage equation. Sources of information received in the course of an examination .. 1, Vinel J. Battery, Gosenergoizdat, 19ROr, p. 35 3-3 6 O. 2. USSR Author's Certificate No. 199942, M.C. H 01 M 45/06 from 1965: and c (ti} 01 ij 1 .2