An electric vehicle, also referred to as an electric drive vehicle, is a moving vehicle using one or more electric motors as driving system. Unlike petroleum-based transportations which are moved by the energy from gasoline, the electric vehicles use electric power as their propulsion. They won't generate waste gas. Noise is also less. During the last few decades, increased concern over the environmental impact of the petroleum-based transportation, along with the spectre of peak oil, has led to renewed interest in electric transportation. Electric power for electric vehicles can be generated from a wide range of sources, including fossil fuels, nuclear power, and renewable sources such as tidal power, solar power, and wind or any combination of those.
In the past, an electric vehicle consumes huge electric power due to their power system. The electric power can only be transmitted to the car through overhead lines. This infrastructure makes the electric vehicles impossible to be popular. Only some of public transportations have access to it. Routes of the public transportation are strictly limited by the lined arrangement. With the development in power systems of electric vehicles, especially in batteries, the electric vehicles become a future star and more and more sources are devoted in this field.
Although electric vehicle batteries are more and more efficient and can support an electric vehicle to run over 150 Km without charge, battery management still has room to improve. Like other electric devices, such as notebook, rechargeable battery cells of electric vehicle are also composed of many small rechargeable battery units (cells) linked to one another in series or parallel. Team work of the cells is the performance of the rechargeable battery. Battery management is more complex for an electric vehicle. This is because cells in a rechargeable battery often up to several thousands.
It is obvious that electric vehicle battery management requests more advanced technique to run the cells and prevent each cell from over-heat, over-voltage and over-current. Meanwhile, when one or more cells are out of order, a battery management system (BMS) must know how to work the rest cells to maximize the efficiency. No matter what kinds of electric devices are used, battery management system is often software or firmware, such as one time programmable (OTP) memory. The battery management system can be updated for new management processes. However, since the BMS is software or firmware, the BMS is not able to be separated from the rechargeable battery. It causes problems to use the rechargeable battery cells. For example, if a rechargeable battery used for car A needs to be changed to car B, due to different performances of the cars, different battery management systems must be applied for different cars.
There are some methods to improve battery management system for electric vehicle. U.S. Pat. No. 7,233,127 discloses a battery management system. Please refer to FIG. 1. The battery management system for managing a number of subsystem circuits and functions of a mobile communication device powered by a battery is disclosed. The battery management system includes a battery monitoring circuit, a user interface, and a battery management module. The battery monitoring circuit is operable to monitor a present battery capacity and generate a battery capacity signal based on the present battery capacity. The user interface is operable to receive a user-input allocation of battery capacity among the subsystem circuits and functions. The battery management module is operable to receive the user-input allocation and the battery capacity signal, and to selectively disable each subsystem circuit or function when each subsystem circuit or function has depleted its allocation of battery capacity. Although users can selectively disable each subsystem circuit or function to achieve the goal of updating current battery management system, it is not applied to any new systematic update, especially to any update during charging of battery. Furthermore, this method is only applied to mobile communication devices.
Another prior art is shown in FIG. 2. U.S. Pat. No. 7,768,235 discloses another battery management system. The battery management system manages a battery of a hybrid vehicle including a motor, a battery, and a main switch connecting the motor and the battery. The battery management system includes a sensing unit and a micro center unit (MCU). The sensing unit measures the current, the voltage and the temperature of the battery. The MCU integrates the battery current to produce an integrated current value, and determines whether the battery is overcharged or over discharged using the integrated current value. It is a typical battery management system for a hybrid vehicle, not for an electric vehicle. Meanwhile, the battery management system can not be updated.
Thus, a charging module and a rechargeable battery for electric vehicles having a battery management system which can be updated for different requirements are still desired. Preferably, the battery management system can be updated when the vehicle or rechargeable battery is being charged.