Battery management system for control of lithium power cells

A system for powering a device, comprising:

• a plurality of rechargeable cells, each rechargeable cell having a positive and a negative terminal, the plurality of rechargeable cells in series electrical communication with each other;
• a connector for connecting the plurality of rechargeable cells to a charger or a device to be powered by the plurality of rechargeable cells;
• a processor for monitoring an input related to the state of charge of each of the rechargeable cells,
• a monitoring circuit, in electrical communication with the processor, the monitoring circuit monitoring the voltage of each of the plurality of rechargeable cells and providing a signal for each of the plurality of rechargeable cells to the processor, the signal representative of a level of voltage measured across the negative and positive terminals of each of the plurality of rechargeable cells, the monitoring circuit including a plurality of switches connecting each of the plurality of rechargeable cells to one of a plurality of bleeder circuits, each of the plurality of switches is individually responsive to an overvoltage signal from the processor directed to at least one of the plurality of switches to close the at least one of the plurality of switches to prevent overcharging of at least one of the plurality of rechargeable cells.

An intelligent battery pack system, comprising:

• a connector to engage a connector disposed in or on a device to be powered;
• a plurality of rechargeable battery cells, each of the cells having a positive and a negative terminal, and each of the cells connected in series by a bus having a positive side connected to a positive terminal of the connector and a negative side connected to a negative terminal of the connector;
• a processor for controlling the operation of a battery pack system;
• a primary protection circuit in electrical communication with the processor, the primary protection circuit including:
• a plurality of monitoring circuits in electrical communication, each one of the plurality of monitoring circuits for monitoring a parameter related to the state of charge of an individual one of the plurality of cells, and
• a plurality of bleed circuits, each of the plurality of bleed circuits connected to an individual one of the cells to bleed the cells in response to the parameter for the cell monitored by the monitoring circuit connected to that cell to prevent an overcharge of the cell;
• a secondary protection circuit for protection of the battery pack system from short circuits;
• a state of charge monitoring circuit, including a sensor for determining an amount of current flowing through the bus, a state of charge processor in electrical communication with the sensor, a state of charge memory in electrical communication with the state of charge processor, the memory for storing information related to the battery cells and also to the amount of current flowing through the bus, wherein the state of charge processor, based on the information stored in the state of charge memory and input from the sensor determines the amount of current available from the battery;
• and
• a communication bus in electrical communication with the connector, the processor, the primary protection circuit, the secondary protection circuit, and the state of charge monitoring circuit for providing for communications between the connector, the processor, the primary protection circuit, the secondary protection circuit, and the state of charge monitoring circuit.