초록 ▼

Improved methods of battery charge and/or discharge control make use of an electrical device which is connected in series with the cell or cells of the battery and which is preferably a permanent part of the battery, so that when the battery terminals are connected in order to charge or discharge th

Improved methods of battery charge and/or discharge control make use of an electrical device which is connected in series with the cell or cells of the battery and which is preferably a permanent part of the battery, so that when the battery terminals are connected in order to charge or discharge the battery, the device provides an automatic guard against excessive battery temperatures and/or current discharges. The device comprises a PTC element which is preferably composed of a conductive polymer composition, and which is in a low resistance state under normal operating conditions but which changes to a high resistance state (and thus reduces the charging current or the discharge current) when the temperature and/or current become excessive.

대표청구항 ▼

A method of recharging a battery comprising one or more secondary cells and having a capacity of C ampere hours, which method comprises passing current through the cell or cells while they are part of a circuit which also comprises a source of DC power and an electrical device which (i) is connected

A method of recharging a battery comprising one or more secondary cells and having a capacity of C ampere hours, which method comprises passing current through the cell or cells while they are part of a circuit which also comprises a source of DC power and an electrical device which (i) is connected in series with the cell or cells of the battery; (ii) is in thermal contact with at least one cell of the battery; (iii) comprises a PTC element and at least two electrodes which are placed so that current flows through said PTC element; and (iv) has an electrical power/temperature relationship and is capable of dissipating heat at a rate such that (A) when the current is initially passed through the circuit, the circuit is in a rapid-charging condition in which there is a rapid-charging current through the cell or cells of the battery of at least 0.25C, and there is a stable equilibrium between the rate at which the device generates heat by I2R heating and the rate at which heat is lost from the device; and (B) when the rapid-charging current has recharged the cell or cells to a certain state of charge and in consequence the cell or cells and the device have reached elevated temperatures, the rate at which the device generates heat by I2R heating exceeds the rate at which heat is dissipated from the device and thus causes the temperature and the resistance of the device to rise rapidly, and thereafter the circuit reaches a trickle-charging condition, in which condition there is a trickle-charging current through the cell or cells which is less than half said rapid-charging current and is from 0.03C to 0.2C amps and in which condition the rate at which the device generates heat by I2R heating is equal to the rate at which heat is dissipated from the device, said trickle-charging condition being maintained so long as current continues to pass through the circuit.