Method and system for battery state of charge estimation by using measured changes in voltage
View Patent ↗A method ( 20 or 30 ) and system ( 40 ) for estimating a battery state of charge can include a memory ( 48 ) for storing at least one among an impedance value, a plurality of values for V drop 0 - 1 , or a plurality of values for V drop 0 - 1 normalized for charge or discharge values providing a stored plurality of values. The system can include a processor ( 44 ) and can measure at least one among V drop C- 0 providing a measured V drop C- 0 value and V drop 0 - 1 for the providing a measured V drop 0 - 1 value. The processor can be programmed to perform the functions of dividing the V drop C- 0 value by the impedance value to estimate a charging current at the battery or comparing the measured V drop 0 - 1 value with a value among the stored plurality of values to estimate the battery state of charge.
1. A method of estimating a battery state of charge, comprising the steps of:
measuring a battery voltage when a charger is on;
measuring a battery voltage when the charger is subsequently turned off;
calculating a difference between the battery voltage when the charger is on and when the charger is subsequently turned off;
dividing the difference by an impedance value stored in a memory to estimate a current that the battery is being charged at; and
storing a plurality of values that are an ohmic measurement proportional to R 1 C 1 in a battery cell model represented as 2 sets of series RC elements in parallel.
2. The method of claim 1 , wherein the method further comprises the step of updating a charge indicator on an electronic device using the current that has been estimated.
3. The method of claim 1 , wherein the method further comprises the step of storing the impedance value in a EPROM.
4. The method of claim 1 , wherein the method further comprises the step of temperature compensating the plurality of values.
5. The method of claim 2 , wherein the step of updating the charge indicator comprises the step of updating a fuel bar.
6. The method of claim 1 , wherein the difference in battery voltage is calculated at the moment between when a charge current was being applied and when the charge current is removed from the battery.
7. A method of estimating a battery state of charge in an electronic device, comprising the steps of:
storing at least one among a plurality of values for V drop 0 - 1 for a given battery and a plurality of values for V drop 0 - 1 for the given battery normalized for charge or discharge values providing a stored plurality of values;
measuring V drop 0 - 1 for the given battery providing a measured V drop 0 - 1 value, wherein measuring V drop 0 - 1 includes measuring a voltage drop associated with R 2 C 2 and a normalized voltage drop to charge/discharge currents in a battery cell model represented as 2 sets of series RC elements in parallel; and
comparing the measured V drop 0 - 1 value with at least one value among the stored plurality of values to estimate the battery state of charge.
8. The method of claim 7 , wherein the method further comprises the step of temperature compensating the stored plurality of values.
9. The method of claim 7 , wherein the step of comparing occurs in one among a charge mode and a discharge mode.
10. A system for estimating a battery state of charge, comprising:
a memory for storing at least one among an impedance value, a plurality of values for V drop 0 - 1 and a plurality of values for V drop 0 - 1 for a given battery normalized for charge or discharge values providing a stored plurality of values
a measuring device measuring at least one among V drop C- 0 for the given battery providing a measured V drop C- 0 value and V drop 0 - 1 for the given battery providing a measured V drop 0 - 1 value, wherein measuring V drop 0 - 1 includes measuring a voltage drop associated with R 2 C 2 and a normalized voltage drop to charge/discharge currents in a battery cell model represented as 2 sets of series RC elements in parallel; and
a processor programmed to perform at least one among the functions of:
dividing the V drop C- 0 value by the impedance value to estimate a current that the battery is being charged at; and
comparing the measured V drop 0 - 1 value with at least one value among stored plurality of values to estimate the battery state of charge.
11. The system of claim 10 , wherein the memory comprises an EPROM.
12. The system of claim 10 , wherein V drop C- 0 comprises a difference between a battery voltage when a charger is on and when the charger is turned off.
13. The system of claim 10 , wherein V drop 0 - 1 comprises a battery voltage delta (V drop) from the moment that the charge current is removed from the battery ( 0 ) to some duration of time thereafter ( 1 ).
14. The system of claim 10 , wherein at least one among the memory, the measuring device, and the processor resides within at least one among a battery and an electronic device.
15. The system of claim 14 , wherein the electronic device is selected among the group comprising a cellular phone, a shaver, a charging device, a two-way radio, a cordless telephone, a cordless toothbrush, a cordless hand tool.
16. The system of claim 12 , wherein the charger is a wireless charger.
17. The system of claim 13 , wherein the charger is a wireless charger.