Patent Application
20080030171
In the following, the invention will be described in detail by referring to the enclosed drawings in which:
In the following detailed description, identical components have been given the same reference numerals, regardless whether they are shown in different embodiments of the present invention. In order to clearly and concisely illustrate the present invention, the drawings may not necessarily be to scale and certain features may be shown in somewhat schematic form.
It is for example envisaged to limit the charging voltage that may be applied to the Li-Ion battery to a voltage of 4.2 V at each Li-Ion battery cell if the temperature of this cell is below 58° C. to 62° C. In a temperature range between 58° C. and 62° C. and 68° C to 72° C the maximum charging voltage that may be applied may be restricted to 3.8 V. If the temperature of the battery cell exceeds the threshold temperature between 68° C. and 72° C. the charging process may be stopped to prevent damage of the battery cell. It should be noted that the present invention may also be applied to other (future) battery cells using another combination of chemical components using other (higher or lower) threshold temperatures and other maximum charging voltage limitations.
The charging module for Li-ion cells is connected to a temperature sensor such as e.g. a bimetallic switch opening a connection at temperatures above 60° C. The charging module for Li-Ion cells/batteries may directly connect the power terminal restricted to a maximum voltage or 3.8 V to the battery terminals (via a diode), so that always possible to apply a charging voltage that reaches a maximum charging voltage of 3.8 V to the Li-Ion battery (cell).
The bimetallic switch (as sensor) may be connected to the sensor terminals looped in between the power terminal limited to a 4.2 V maximum charging voltage and the Li-Ion battery terminal, so that the opening of the switch/sensor may interrupt the temperature sensor terminals. If the temperature of the battery cell is below 60° a charging voltage (current) restricted to a maximum voltage of 4.2 V is supplied to the Li-Ion battery. In this case the diode in the 3.8 V power supply line serves to prevent any currents from the (connected) maximum 4.2 V to the maximum 3.8 V terminals of the power supply. If the temperature of the Li-Ion battery cell is above 60° C. the bimetallic switch interrupts the maximum 4.2 V connection to the battery (cell) and the Li-Ion battery cell is charged by a voltage limited to a maximum charging voltage of reduced 3.8 V from the 3.8 V power terminals.
In the depicted embodiment the mobile telephone is provided with a temperature sensor thermally connected to the battery (cell) and electrically connected to the MCU. It is for example possible to use a built-in temperature sensor (e.g. in an application specific integrated circuit (ASIC) of e.g. a mobile phone MCU) to determine the temperature of the battery (cell). It is also envisaged to use an A-D converter in the phone ASIC (and a software algorithm) to determine the battery voltage and temperature. It is possible to implement the invention by a software running in the Main Computing Unit (MCU) that controls the charge switch, so that charging is continued even on temperatures over e.g. 60° C. (but below 70° C.), but only as long as e.g. the Li-Ion battery voltage is below 3.8 V.
With the present invention it is possible to use less heat limitations for charging batteries. This allows devices such as phones to be smaller and/or have more high-yielding hardware with the same user experience. Reduced battery voltage in high temperature will slow battery degradation more than high battery voltage in high temperature.
This application contains the description of implementations and embodiments of the present invention with the help of examples. It will be appreciated by a person skilled in the art that the present invention is not restricted to details of the embodiments presented above, and that the invention can also be implemented in another form without deviating from the characteristics of the invention. The embodiments presented above should be considered illustrative, but not restricting especially to the voltage and temperature values given with respect to Li especially Li-Ion batteries. It should be noted that other (future) battery cells (with other chemical components) may require other (higher or lower) threshold temperatures and other maximum charging voltages. Thus the possibilities of implementing and using the invention are only restricted by the enclosed claims. Consequently various options of implementing the invention as determined by the claims, including equivalent implementations, also belong to the scope of the invention.
