Method and circuitry to calculate the state of charge of a battery/cell

[0024] In the course of the detailed description to follow, reference will be made to the attached drawings. These drawings show different aspects of the present inventions and, where appropriate, reference numerals illustrating like structures, components, materials and/or elements in different figures are labeled similarly. It is understood that various combinations of the structures, components, and/or elements, other than those specifically shown, are contemplated and are within the scope of the present inventions.

[0025] Moreover, there are many inventions described and illustrated herein. The present inventions are neither limited to any single aspect nor embodiment thereof, nor to any combinations and/or permutations of such aspects and/or embodiments.

[0026] Moreover, each of the aspects of the present inventions, and/or embodiments thereof, may be employed alone or in combination with one or more of the other aspects of the present inventions and/or embodiments thereof. For the sake of brevity, certain permutations and combinations are not discussed and/or illustrated separately herein.

[0027] FIGS. 1A-1C illustrate block diagram representations of exemplary adaptive charging circuitry in conjunction with a battery/cell, according to at least certain aspects of certain embodiments of the present inventions, wherein FIG. 1B includes discrete memory coupled to the control circuitry, and FIG. 1C illustrates circuitry external which accesses the memory to store one or more predetermined ranges employed by control circuitry in conjunction with adapting, adjusting and/or controlling one or more characteristics of the charge or current applied to or injected into the battery/cell so that a change in voltage at the terminals of the battery/cell in response to such charge or current is within a predetermined range and/or below a predetermined value during a charging or recharging sequence, operation or cycle;

[0028] FIG. 1D illustrates, in block diagram form, exemplary adaptive charging circuitry in conjunction with a battery/cell (which may include two terminals (for example, positive and negative terminals), according to at least certain aspects of certain embodiments of the present inventions, wherein in this embodiment, the charging circuitry may include voltage source and/or current source, and the monitoring circuitry may include voltage and/or current sensors (for example, a voltmeter and/or a current meter);

[0029] FIGS. 2A-2D illustrate exemplary waveforms illustrating a plurality of exemplary charging signals and discharging signals of an exemplary charging technique, wherein such charging signals may generally decrease according to a predetermined rate and/or pattern (for example, asymptotically, linearly or quadratically) as the terminal voltage of the battery/cell increases during a charging or recharging sequence, operation or cycle (see, FIGS. 2B and 2D); notably, a charging or recharging sequence, operation or cycle may include charging signals (which, in total, inject or apply charge into the battery/cell) and discharging signals (which, in total, remove charge from the battery/cell);

[0030] FIGS. 3A-3N illustrate exemplary charge and/or discharge packets of the charging and discharging signals (which are exemplary illustrated in FIGS. 2A-2D), wherein such charge and discharge packets may include one or more charge pulses and one or more discharge pulses; notably, in one embodiment, each charge signal of FIGS. 2A-2D may include a plurality of packets (for example, about 100 to about 50,000 packets) and, in one embodiment, each packet may include a plurality of charge pulses, discharge pulses and rest periods; notably, the pulses may be any shape (for example, rectangular, triangle, sinusoidal or square); in one exemplary embodiment, the charge and/or discharge pulses of the packet may include a temporal duration of between about 1 ms to about 500 ms, and preferably less than 50 ms; moreover, as discussed in detail below, one, some or all of the characteristics of the charge and discharge pulses (for example, pulse amplitude, pulse width/duration and pulse shape) are programmable and/or controllable via charging circuitry wherein the amplitude of the positive and/or negative pulses may vary within the packet (and are programmable and/or controllable), the duration and/or timing of the rest periods may vary within the packet (and are programmable and/or controllable) and/or, in addition, such pulses may be equally or unequally spaced within the packet; the combination of charging pulses, discharging pulses and rest periods may be repetitive and thereby forms a packet that may be repeated; all combination or permutations of pulse, pulse characteristics, periods, packets and signal characteristics and configurations are intended to fall within the scope of the present inventions;

[0031] FIG. 4A is a flowchart of an exemplary process of determining, adapting and/or controlling the characteristics of a charging current based on or using a change in voltage at the terminals of the battery/cell in response to a charge packet (which may include one or more charge pulses and one or more discharge pulses), according to certain aspects of the present inventions; wherein the charging techniques and/or circuitry adapt, adjust and/or control one or more characteristics of the charge or current applied to or injected into the battery/cell so that the change in voltage at the terminals of the battery/cell in response to one or more subsequent charge packets is within a predetermined range and/or below a predetermined value during a charging or recharging sequence, operation or cycle;

[0032] FIG. 4B is a flowchart of an exemplary process of adaptively determining the characteristics of the discharging current based on or using a change in voltage at the terminals of the battery/cell in response to a discharge packet (which may include one or more discharge pulses and one or more charge pulses), according to certain aspects of the present inventions; wherein the discharging techniques and/or circuitry adapt, adjust and/or control one or more characteristics of the charge or current removed from the battery/cell so that the change in voltage at the terminals of the battery/cell in response to one or more subsequent discharge packets is within a predetermined range and/or below a predetermined value during a charging sequence, operation or cycle;

[0033] FIG. 5A illustrates an exemplary charge packet having a charge pulse including a charging period (T_charge) followed by a rest period (T_rest) wherein the period of the charge packet is identified as T_packet, according to certain aspects of the present inventions; an exemplary terminal voltage response of the battery/cell to such charge packet is illustrated wherein a first voltage (V₁) is identified (which correlates to the beginning of the charge pulse), a second voltage (V₂) is identified (which correlates to the end of the charge pulse and/or the peak of the change in the terminal voltage due to the charge pulse) and a third voltage (V₃) is identified (which correlates to the end of the charge packet, the beginning of an immediately subsequent packet (for example, charge or discharge packet) and/or the end of the rest period of the charge packet);

[0034] FIG. 5B illustrates an exemplary charge packet having a charge pulse (which injects charge into the battery/cell) and a discharge pulse (which removes charge from the battery/cell) wherein the charge pulse includes a charging period (T_charge) and the discharge pulse includes a discharging period (T_discharge), according to certain aspects of the present inventions; notably, in this exemplary charge packet, an intermediate rest period (T_inter) is disposed between the charge and discharge pulses, and a rest period (T_rest) is disposed after the discharge pulse and before the next packet; an exemplary terminal voltage response of the battery/cell to such charge packet is illustrated wherein a first voltage (V₁) is identified (which correlates to the beginning of the charge pulse), a second voltage (V₂) is identified (which correlates to the end of the charge pulse and/or the peak of the change in the terminal voltage due to the charge pulse), a third voltage (V₃) is identified (which correlates to the beginning of the discharge pulse), a fourth voltage (V₄) is identified (which correlates to the end of the discharge pulse and/or the peak of the change in the terminal voltage due to the discharge pulse) and a fifth voltage (V₅) is identified (which correlates to the end of the charge packet, the beginning of an immediately subsequent packet (for example, charge or discharge packet) and/or the end of the rest period of the charge packet); notably, as discussed in detail below, one, some or all of the characteristics of the charge pulses (for example, pulse amplitude, pulse width/duration and pulse shape) are programmable and/or controllable via charging circuitry wherein the amplitude of the positive and/or negative pulses may vary within the packet (and are programmable and/or controllable), the duration and/or timing of the rest periods may vary within the packet (and are programmable and/or controllable) and/or, in addition, such pulses may be equally or unequally spaced within the packet; the combination of charging pulses, discharging pulses and rest periods may be repetitive and thereby forms a packet that may be repeated; all combination or permutations of pulse, pulse characteristics, periods, packets and signal characteristics and configurations are intended to fall within the scope of the present inventions; moreover, discharge packets may have similar characteristics as charge packets except, however, a net charge is removed from the battery/cell; for the sake of brevity, the discussion/illustration with respect to discharge packet will not be repeated;

[0035] FIG. 6A illustrates an exemplary charge packet having a charge pulse wherein the amplitude of the charge pulse is greater than the amplitude of the charge pulse of FIG. 5A wherein the charging circuitry, in response to instructions from the control circuitry, adjust the amplitude of the charge pulse to increase the responsive terminal voltage so that the change in terminal voltage of the battery/cell is within a predetermined range and/or below a predetermined value during a charging or recharging sequence, operation or cycle; an exemplary terminal voltage response of the battery/cell to such a charge pulse is illustrated wherein a first voltage (V₁) is identified (which correlates to the beginning of the charge pulse) and a second voltage (V_2′) is identified (which correlates to the end of the charge pulse and/or the peak of the change in the terminal voltage due to the charge pulse) wherein the amplitude of the responsive terminal voltage is greater than the amplitude of the terminal voltage of the battery/cell which is responsive to the charge pulse of FIG. 5A;

[0036] FIG. 6B illustrates an exemplary charge packet having a charge pulse wherein the amplitude of the charge pulse is less than the amplitude of the charge pulse of FIG. 5A wherein the charging circuitry, in response to instructions from the control circuitry, adjust the amplitude of the charge pulse to decrease the responsive terminal voltage so that the change in terminal voltage of the battery/cell is within a predetermined range and/or below a predetermined value during a charging or recharging sequence, operation or cycle; an exemplary terminal voltage response of the battery/cell to such a charge pulse is illustrated wherein a first voltage (V₁) is identified (which correlates to the beginning of the charge pulse) and a second voltage (V_2″) is identified (which correlates to the end of the charge pulse and/or the peak of the change in the terminal voltage due to the charge pulse) wherein the amplitude of the responsive terminal voltage is less than the amplitude of the terminal voltage of the battery/cell which is responsive to the charge pulse of FIG. 5A;

[0037] FIG. 7 illustrates of three exemplary changes in net effective charging current of a battery/cell over time (which, in one embodiment, is a function of the state of charge of the battery/cell), according to certain aspects of the present inventions;

[0038] FIG. 8 is an exemplary illustration of the relaxation time as function of state of charge of a battery/cell (rated at 2.5 A.h); notably, the data was acquired using a square-like charging pulse having duration of 20 ms;

[0039] FIG. 9A illustrates an exemplary charge packet having two charge pulses (each including a charging period (T_charge)) followed by a rest period (T_rest) wherein the period of the charge packet is identified as T_packet, according to certain aspects of the present inventions; an exemplary terminal voltage response of the battery/cell to such charge packet is illustrated wherein a first voltage (V₁) is identified (which correlates to the beginning of the first charge pulse and, in this embodiment, the beginning of the packet), a second voltage (V₂) is identified (which correlates to the end of the first charge pulse and/or the peak of the change in the terminal voltage due to the first charge pulse), a third voltage (V₃) is identified (which correlates to the beginning of the second charge pulse), a fourth voltage (V₄) is identified (which correlates to the end of the second charge pulse and/or the peak of the change in the terminal voltage due to the second charge pulse) and a fifth voltage (V₅) is identified (which correlates to when the terminal voltage of the battery/cell decays to a predetermined value (for example, preferably less than 10% of peak deviation relative to the terminal voltage of the battery/cell when the charge/discharge packet is applied (here, V₁) and, more preferably, less than 5% of such peak deviation); wherein the partial relaxation time of the battery/cell due to the exemplary charge packet is the amount of time between (i) the termination/end of the second charge pulse and/or the peak of the change in the terminal voltage due to the second charge pulse and (ii) when the terminal voltage of the battery/cell decays to a predetermined value (for example, preferably less than 10% of peak deviation and, more preferably, less than 5% of peak deviation);

[0040] FIG. 9B illustrates an exemplary charge packet having a charge pulse (which injects charge into the battery/cell) and a discharge pulse (which removes charge from the battery/cell) wherein the charge pulse includes a charging period (T_charge) and the discharge pulse includes a discharging period (T_discharge), according to certain aspects of the present inventions; notably, in this exemplary charge packet, an intermediate rest period (T_inter) is disposed between the charge and discharge pulses, and a rest period (T_rest) is disposed after the discharge pulse and before the next packet; an exemplary terminal voltage response of the battery/cell to such charge packet is illustrated wherein a first voltage (V₁) is identified (which correlates to the beginning of the charge pulse and, in this embodiment, the beginning of the packet), a second voltage (V₂) is identified (which correlates to the end of the charge pulse and/or the peak of the change in the terminal voltage due to the charge pulse), a third voltage (V₃) is identified (which correlates to the end of the discharge pulse and/or the peak of the change in the terminal voltage due to the discharge pulse) and a fourth voltage (V₄) is identified (which correlates to when the terminal voltage of the battery/cell decays to a predetermined value (for example, preferably less than 10% of peak deviation relative to the terminal voltage of the battery/cell when the charge/discharge packet is applied (here, V₁) and, more preferably, less than 5% of peak deviation); wherein the relaxation time of the battery/cell due to the exemplary charge packet is the amount of time between (i) the termination/end of the discharge pulse and/or the peak of the change in the terminal voltage due to the discharge pulse (see, V₃ and T₁) and (ii) when the terminal voltage of the battery/cell decays to a predetermined value (for example, preferably less than 10% of peak deviation and, more preferably, less than 5% of peak deviation) (see, V₄ and T₂); notably, as discussed in detail herein, one, some or all of the characteristics of the charge pulses (for example, pulse amplitude, pulse width/duration and pulse shape) are programmable and/or controllable via charging circuitry wherein the amplitude of the positive and/or negative pulses may vary within the packet (and are programmable and/or controllable), the duration and/or timing of the rest periods may vary within the packet (and are programmable and/or controllable) and/or, in addition, such pulses may be equally or unequally spaced within the packet; the combination of charging pulses, discharging pulses and rest periods may be repetitive and thereby forms a packet that may be repeated; all combination or permutations of pulse, pulse characteristics, periods, packets and signal characteristics and configurations are intended to fall within the scope of the present inventions; moreover, discharge packets may have similar characteristics as charge packets except, however, a net charge is removed from the battery/cell; for the sake of brevity, the discussion/illustration with respect to discharge packet will not be repeated;

[0041] FIG. 9C illustrates an exemplary charge packet like that of FIG. 9B wherein the packet includes a charge pulse (which injects charge into the battery/cell) and a discharge pulse (which removes charge from the battery/cell) wherein the charge pulse includes a charging period (T_charge) and the discharge pulse includes a discharging period (T_discharge), according to certain aspects of the present inventions; in this illustration, a partial relaxation time corresponding to the charge pulse of the packet is also depicted (see, Relaxation time_AB) wherein the relaxation time associated with the charge pulse is equal to the difference between T_A (which coincides with V₂) and T_B (which coincides with V_4′); notably, the relaxation time of the battery/cell in response to the charge packet having a charge pulse and discharge pulse may be shorter than the relaxation time of the battery/cell in response to the charge packet not having a discharge pulse (compare ΔT_BA and ΔT₂₁) and, as such, under certain circumstances, the total charging time of a charging sequence employing packets having charge and discharge pulses may be shorter than the charging time of a charging sequence employing packets having no discharge pulses to shorten or reduce the relaxation time;

[0042] FIGS. 10A-10F are flowcharts of an exemplary processes of determining, adapting and/or controlling the characteristics of a charging current based on, using and/or in accordance with relaxation time of the battery/cell in response to a charge packet (which may include one or more charge pulses and/or one or more discharge pulses) and/or discharge packet (which may include one or more charge pulses and/or one or more discharge pulses), according to certain aspects of the present inventions; wherein the charging techniques and/or circuitry adapt, adjust and/or control one or more characteristics of the charge and/or discharge pulses of one or more charge or discharge packets based on, using and/or in accordance with partial relaxation time of the battery/cell; notably, charging techniques and/or circuitry may employ data which is representative of the partial or full relaxation time to determine, calculate and/or estimate the state of charge of the battery/cell (see, for example, FIGS. 10E and 10F);

[0043] FIG. 11 is an illustration depicting three responses to a charge packet having a charge pulse (which injects charge into the battery/cell) and a discharge pulse (which removes charge from the battery/cell) wherein a first response (A) includes a significant “overshoot” whereby the discharge pulse removed too little charge from the battery/cell, a second response (B) that include no significant “overshoot” or “undershoot” wherein the discharge pulse removes a suitable amount of charge which provides the fastest partial relaxation time of the three responses, and a third response (C) includes a significant “undershoot” whereby the discharge pulse removed is too much charge from the battery/cell;

[0044] FIG. 12 is a flowchart of an exemplary process of determining, adapting and/or controlling the characteristics of a charging current based on, using and/or in accordance with (i) a change in voltage at the terminals of the battery/cell in response to a charge or discharge packet (which may include one or more charge pulses and/or one or more discharge pulses) and (ii) partial relaxation time of the battery/cell in response to a charge or discharge packet, according to certain aspects of the present inventions; wherein the charging techniques and/or circuitry adapt, adjust and/or control one or more characteristics of the charge and/or discharge pulses of one or more charge or discharge packets based on, using and/or in accordance with a change in voltage at the terminals of the battery/cell in response to one or more packets and the partial relaxation time of the battery/cell in response to such one or more packets;

[0045] FIG. 13A illustrates the partial relaxation of the terminal voltage of the battery/cell following the application of a charging current pulse based on or at three different states of charge values of an exemplary battery/cell (a commercial lithium oxide cobalt cell rated at 2.5 A.h); notably, the relaxation curves are distinctly different; a 4.20 A-current pulse is 734 ms in duration; the voltage difference is measured relative to a “resting” open circuit voltage immediately preceding application of the current pulse to the battery/cell;

[0046] FIG. 13B illustrates the peak increase in voltage of the battery/cell described in FIG. 13A, following the application of a 2.5-A, 734 ms pulse, as a function of the state of charge of the battery/cell;

[0047] FIG. 14A illustrates an exemplary trend of the change in partial relaxation time as the state of health of the battery/cell degrades;

[0048] FIG. 14B illustrates actual measurements of the partial relaxation time as the state of health of the battery/cell degrades with increasing number of charge/discharge cycle numbers (notably, each cycle is a full charge followed by a complete discharge);

[0049] FIG. 15A illustrates an exemplary embodiment of the overpotential of the battery/cell wherein at the end of the “full” or “complete” relaxation time of the battery/cell, the overpotential of the battery/cell may be determined; notably, the overpotential may be characterized as the voltage difference between the terminal voltage of the battery/cell at the initiation of the charge signal and the terminal voltage of the battery/cell when the battery/cell is at full equilibrium (which may be characterized as when the terminal voltage of the battery/cell is substantially or relatively constant or unchanging under no charging current—which, for a conventional lithium ion battery/cell, is typically after a temporal duration of, for example, 1 to 1,000 seconds);

[0050] FIG. 15B illustrates an exemplary charge signal (which may include a plurality of charge packets and/or discharge packets—each packet having one or more charge pulses and/or one or more discharge pulses and an exemplary terminal voltage response of the battery/cell to such charge signal wherein a first voltage (V₁) is identified (which correlates to the voltage of the battery/cell at the end/termination of the charge signal) at time T₁ and a second voltage (V₂) at time T₂ is identified (which correlates to a predetermined percentage of voltage V₁) wherein the control circuitry may determine the overpotential or “full” relaxation time of the battery/cell based on or using the form, shape and/or rate of decay of the terminal voltage; the predetermined percentage is preferably greater than 50% and, more preferably, between 60% and 95%);

[0051] FIG. 15C illustrates an exemplary charge signal (which may include a plurality of charge packets and/or discharge packets—each packet having one or more charge pulses and/or one or more discharge pulses and an exemplary terminal voltage response of the battery/cell to such charge signal wherein a first voltage (V₁) is identified (which correlates or is related to the voltage of the battery/cell at the beginning/initiation of the charge signal) at time T₁ and a second voltage (V₂) at time T₂ is identified (which correlates to a predetermined percentage of voltage V₁) wherein the control circuitry may determine the overpotential or “full” relaxation time of the battery/cell based on or using the form, shape and/or rate of decay of the terminal voltage; the predetermined percentage is preferably greater than 50% and, more preferably, between 60% and 95%);

[0052] FIG. 16 is a flowchart of an exemplary process of determining, adapting and/or controlling the characteristics of a charging current based on or using the overpotential or full relaxation time of the battery/cell in response to a charging signals (which may include one or more charge packets/pulses and one or more discharge packets/pulses), according to certain aspects of the present inventions; wherein the charging techniques and/or circuitry adapt, adjust and/or control one or more characteristics of the charge or current applied to or injected into the battery/cell so that the overpotential or full relaxation time of the battery/cell in response to one or more subsequent charging is less than a predetermined value and/or within a predetermined range during subsequent charging or recharging of the charge operation or cycle;

[0053] FIGS. 17A-17E illustrate, in flowchart like form, adaptive charging techniques having one or more adaption loops wherein each adaption loop estimates, calculates, measures and/or determines one or more different parameters; notably, the adaptation loops may be implemented alone/separately or in combination; all combination or permutations thereof are intended to fall within the scope of the present inventions;

[0054] FIGS. 18A-18D illustrate exemplary parameters of the adaption loops including, for example, (i) a first adaption loop based on change in terminal voltage in response to one or more charge/discharge pulses (of one or more charge/discharge packets) and/or the partial relaxation time of a pulse/packet, (ii) a second adaption loop based on SOC of the battery/cell and/or full relaxation time or overpotential, (iii) a third adaption loop based on SOH (or changes therein) of the battery/cell, and (iv) a fourth adaption loop based on the temperature of the battery/cell (notably, in this embodiment, the system includes a temperature sensor to provide data which is representative of the temperature of the battery/cell);

[0055] FIGS. 19A-19D illustrate exemplary charge pulses having different shapes and pulse widths; all combination or permutations of charge pulse characteristics are intended to fall within the scope of the present inventions;

[0056] FIGS. 20A-20D illustrate exemplary discharge pulses having different shapes and pulse widths; all combination or permutations of discharge pulse characteristics are intended to fall within the scope of the present inventions;

[0057] FIG. 21A illustrates an exemplary measurement the current and change in voltage at the terminals of a battery/cell immediately after the application of a current pulse (which, in this example, is 4.2 A); wherein in the first few milliseconds (a time period substantially that may be faster than any chemical reaction or ion transport to take place within the battery/cell), the voltage rise is due to ohmic drop in the battery/cell; notably, the dashed line pertains to the voltage (left axis) and the solid line pertains to the current (right axis); and

[0058] FIG. 21B illustrates the impedance of the battery/cell corresponding to FIG. 21A, wherein dividing the voltage drop by the current yields the ohmic impedance of the battery/cell; notably, in this particular example, the impedance of the battery/cell is about 50 milliohms;

[0059] FIG. 22 illustrates, in block diagram form, exemplary charging circuitry in conjunction with a battery/cell (which may include two terminals (for example, positive and negative terminals) and a user interface which provides information regarding the characteristics of the battery/cell and/or charging thereof (for example, the state of charge of the battery/cell), according to at least certain aspects of certain embodiments of the present inventions, wherein in one embodiment, the charging circuitry may include voltage source and/or current source, and the monitoring circuitry may include voltage and/or current sensors (for example, a voltmeter and/or a current meter);

[0060] FIGS. 23A-23C illustrate, in block diagram form, exemplary user interfaces, which may include a display and/or a speaker wherein the display may be a conventional fuel gauge (for example, displayed figuratively (such as bars or tank fill) and/or numerically (for example, as a percentage)) depicting the amount of charge or a charge state of the battery/cell and the speaker provides audible information pertaining to the amount of charge or a charge state of the battery/cell; and

[0061] FIG. 24 illustrates the voltage of the battery/cell as a function of available stored charge in the battery/cell) for a given state of health (SOH) of the battery/cell; in the context of a typical lithium-ion battery, the voltage-charge curve changes as the state of health (SOH) of the battery/cell degrades wherein the voltage-charge curve shifts indicating that the amount of available charge (Q) at a given voltage (V_m) measured at the terminals of a battery/cell at a first state of health (SOH₁) is greater than at a second state of health (SOH₂) which is greater than at a third state of health (SOH₃), wherein the SOH of the battery/cell changes from the first SOH, to the second SOH to the third SOH, for example, as the battery/cell ages, deteriorates and/or degrades.