Systems and methods for constructing a battery pack
Methods and systems for constructing a battery, the battery including at least two energy storage sections connected in parallel to a common module power bus, the energy storage sections including at least one battery cell and at least one section disconnect device capable of disconnecting the at least two energy sections from the module power bus, and, a section protection device to control the section disconnect device based on data from the energy storage sections. In an embodiment, the battery can include at least two battery modules connected in series using an interlock signal, where the battery modules include a module protection device having an interlock signal controller and fault logic for controlling the interlock signal controller, such that the modules can control the interlock signal and hence a disconnect device that receives the interlock signal and is connected between the modules and a load and/or charger.
1. A battery pack comprising:
at least one battery module connected to battery pack terminals, plural modules, if provided, being connected in desired configuration to achieve a desired voltage and current capability;
each battery module comprising at least two energy storage sections connected in parallel across positive and negative module power buses,
said battery pack further comprising module monitoring and protection circuitry for monitoring one or more of the voltage across, current through, or temperature of the module(s), and for providing an interlock signal that controls disconnection of the module(s) from at least one of a charge source and a load responsive to detection of a module fault, wherein said module monitoring and protection circuitry does not control connection of the individual energy storage sections to the module power buses;
each energy storage section comprising:
(1) at least four battery cells connected in at least two series-connected strings, each of the corresponding single cells of each string also being connected in parallel to form at least two cell groups, each cell group comprising at least two cells connected in parallel, whereby each cell group thus comprises single cells connected in parallel,
(2) at least one device for monitoring the operation of the battery cells in each energy storage section, and for providing a disconnect control signal responsive to the operational state of the cells within the energy storage section, said at least one device being capable of separately monitoring each cell group of single cells connected in parallel, such that the cells of each cell group of single cells connected in parallel are monitored collectively; and
(3) a controllable element for permanently disconnecting the entire energy storage section from the module power buses responsive to said disconnect control signal,
wherein the only means for disconnecting the energy storage sections from the module power buses are comprised by the energy storage sections; and
whereby the remaining energy storage section(s) continue to function to deliver energy upon disconnection of any of the other energy storage sections.
2. The battery pack of claim 1 , wherein said device for monitoring the operation of the at least four battery cells of each energy storage section separately monitors at least one of voltage, temperature, or current of each of the cell groups of single cells connected in parallel.
3. The battery pack of claim 1 , where the controllable element of each energy storage section is thermally activated.
4. The battery pack of claim 3 , where the controllable element of each energy storage section includes a resistive heating device arranged to heat a first thermally-activated controllable cut-off device.
5. The battery pack of claim 4 , wherein each controllable element further includes a second thermally-activated controllable cut-off device connected to cut off current to said resistive heating device after said first thermally-activated controllable cut-off device has been actuated.
6. The battery pack of claim 1 , where each energy storage section further comprises a fuse, which is blown responsive to a current beyond its rating.
7. The battery pack of claim 1 , where each energy storage section includes a circuit for comparing the voltage on said individual cell groups of single cells connected in parallel to a predetermined battery cell voltage or to one another, and an equalizer circuit for directing energy from at least one cell group of single cells connected in parallel to an electrically resistive device to better match the characteristics of the cell group of single cells connected in parallel to that of other cell groups of single cells connected in parallel within said energy storage section.
8. The battery pack of claim 1 , wherein said battery pack has a minimum capacity rating, and the number of energy storage sections and their relative capacity are chosen correspondingly so that said battery pack is capable of supplying power at its rated capacity after permanent disconnection of at least one of said energy storage sections responsive to detection of a malfunction.