초록 ▼

A battery monitoring device of a battery pack configured for powering a cordless power tool may include an integrated circuit connected to a microprocessor of the pack that is external to the integrated circuit, and which is connected to each of N battery cells of the pack. The integrated circuit m

A battery monitoring device of a battery pack configured for powering a cordless power tool may include an integrated circuit connected to a microprocessor of the pack that is external to the integrated circuit, and which is connected to each of N battery cells of the pack. The integrated circuit may be configured to take, singly or sequentially, a sampled reading comprising one of an individual cell voltage or a total pack voltage for all cells in the pack. The sampled reading is filtered in the integrated circuit prior to being read by the microprocessor.

대표청구항 ▼

We claim: 1. A battery monitoring device of a battery pack configured for powering a cordless power tool, comprising: an integrated circuit in the pack and connected to a microprocessor of the pack that is external to the integrated circuit, and connected to each of N battery cells of the pack, the

We claim: 1. A battery monitoring device of a battery pack configured for powering a cordless power tool, comprising: an integrated circuit in the pack and connected to a microprocessor of the pack that is external to the integrated circuit, and connected to each of N battery cells of the pack, the integrated circuit configured to take, singly or sequentially, a sampled reading comprising one of an individual cell voltage or a total pack voltage for all cells in the pack, wherein the sampled reading is filtered in the integrated circuit prior to being read by the microprocessor; wherein the integrated circuit include a logic controller in communication via a serial communication interface with the microcontroller and configured to process a given serial data command received from the microprocessor for taking sampled readings from one or more of the N cells, or to direct selective discharging of one or more of the N cells. 2. The device of claim 1, wherein the integrated circuit is further configured to selectively discharge one or more of the N cells as the battery pack is being charged. 3. The device of claim 2, wherein the microprocessor issues commands to sequentially and periodically measure individual cell voltages and total pack voltage, compare the measured individual cell voltage values received from the integrated circuit to a given threshold as the pack is being charged, and selectively discharge those cells not satisfying the threshold. 4. The device of claim 3, wherein the threshold is an average cell voltage value for all cells that is determined from the total pack voltage measured by the integrated circuit, the average cell voltage value being stored and updated over the duration of charge in the microprocessor. 5. The device of claim 4, wherein the cell having a maximum differential voltage above the average cell voltage is discharged during the charge until its measured cell voltage has dropped to equal the average cell voltage. 6. The device of claim 4, wherein any cells exceeding the average cell voltage are discharged during the charge until their respective measured cell voltage has dropped to equal the average cell voltage. 7. The device of claim 3, wherein the threshold is set as the highest voltage cell measured in a given cycle of measurements, and the microprocessor issues a command to the integrated circuit to discharge the highest voltage cell as evident from the given cycle of measurements. 8. The device of claim 3, wherein the threshold is set as the X highest voltage cells as measured in a given cycle of measurements, and the microprocessor issues a command to the integrated circuit to discharge the X highest voltage cells until these cells measured voltages evident from the given cycle of measurements. 9. The device of claim 3, wherein the threshold is an integer Y (Y≧1) multiplied by a minimum voltage for the cell that is set in advance, and the microprocessor issues a command to the integrated circuit to discharge those cells exceeding Y*preset minimum voltage. 10. The device of claim 1, wherein N is greater than or equal to 5. 11. The device of claim 1, wherein the integrated circuit is operatively connected to a corresponding channel of each cell in the battery pack, each channel having a channel input from its cell to the integrated circuit, and the integrated circuit further includes gate drive circuitry in communication with the logic controller for controlling one or more of a plurality of field-effect transistors (FETs), each FET corresponding to a given channel and operable to selectively discharge its corresponding cell, based on a given data command received from the microprocessor. 12. The device of claim 1, wherein the integrated circuit is operatively connected to a corresponding channel of each cell in the battery pack, each channel having a channel input from its cell to the integrated circuit, and the integrated circuit further includes; a switch matrix connected to each of the channels and in communication with the logic controller, and which is adapted to select given channels to output the sampled reading based on a control signal from the logic controller, and a capacitor connected to the output of the switch matrix for storing the sampled reading, wherein the sampled reading is digitally filtered as the capacitor is being charged so that an average voltage value is stored in the capacitor, and wherein, after a controlled delay to allow the capacitor to charge, the average voltage value stored on the capacitor is output from the integrated circuit for reading by the microprocessor. 13. The device of claim 12, wherein, based on a data command received for measuring a given cell voltage or a total pack voltage, the logic controller sends control signals to close the switch matrix and select given channels for taking the sampled reading, and to align switch positions for a group of switches such that the capacitor becomes part of an RC filtering circuit at the output of the switch matrix to filter the output as the capacitor charges up with the sampled reading. 14. The device of claim 12, wherein the integrated circuit further includes an auxiliary circuit thereon that is connected to the output of the switch matrix for connection to an external differential amplifier, wherein the external amplifier can be selectively connected to the switch matrix output to provide an alternative to the capacitor for taking sampled readings. 15. The device of claim 1, wherein the cells of the battery pack have a lithium-ion cell chemistry. 16. The device of claim 1, wherein a nominal voltage rating of the battery pack is at least 18V. 17. A method of monitoring battery cells of a battery pack that is configured for powering a cordless power tool, comprising: receiving a first serial data command from a microprocessor of the pack to take a voltage measurement from channels connected to one or more of the cells, the voltage measurement embodied as a differential voltage value measured across an individual cell or a differential voltage value measured across all cells to reflect a total pack voltage, storing the voltage measurement in a capacitor, wherein the voltage measurement is filtered so that the capacitor charges up to an average of the differential voltage value for a given cell or across all cells of the pack, and receiving a second serial data command to connect the capacitor to a buffer amplifier so that the microprocessor can read the average voltage value off the capacitor.