# US 11,114,705 B2 · Current measurement and voltage control approach > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,114,705 B2 - Document ID: US11114705B2 - Status: Granted - Kind: B2 - Application number: 16/686,899 - Filed: 2019-11-18 - Published: 2020-05-21 - Granted: 2021-09-07 - Earliest claimed: 2018-11-21 - Assignees: Honeywell International Inc. - Applicants: Honeywell International Inc. - Inventors: Ralf Schroeder Genannt Berghegger; Claas Gerdes - Web page: https://patentgrep.com/patent/US11114705B2 ## CPC - H01M 10/44: Methods for charging or discharging (circuits for charging H02J7/00) - H01M 10/448: {End of discharge regulating measures} - G01R 31/3842: combining voltage and current measurements - H01M 10/425: {Structural combination with electronic components, e.g. electronic circuits integrated to the outside of the casing (printed circuits H05K1/00)} - H01M 10/4257: {Smart batteries, e.g. electronic circuits inside the housing of the cells or batteries} - H01M 10/48: Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte (constructional details of current conducting connections for detecting conditions inside cells or batteries, e.g. details of voltage sensing terminals, H01M50/569) - H02J 7/90: Regulation of charging or discharging current or voltage - H01M 2010/4271: {Battery management systems including electronic circuits, e.g. control of current or voltage to keep battery in healthy state, cell balancing} - Y02E 60/10: Energy storage using batteries - H01M: PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) - H02J: ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY - Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION ## Abstract A circuit that indicates a warning of low battery life so that an instrument supported by a battery, may have the battery replaced before the battery dies. A switch and series resistor may be connected between the battery and a capacitor. The switch may turn on when the voltage on the capacitor is below a first predetermined voltage limit, and the switch may be turned off when the voltage at the capacitor is above a second predetermined voltage limit. When the switch is on, a voltage on the resistor can be measured and current consumption can be calculated with measured voltage, resistor value and duty cycle of the switch. When the battery is discharged, its internal resistance and then its duty cycle may increase. When the duty cycle hits 100 percent, the battery may be nearly dead but with enough life for the circuit to issue the low battery warning. ## Claims ### Claim 1 A voltage measurement and current control system comprising: a switch; a battery having a first terminal connected to a first terminal of the switch, and a second terminal connected to a reference voltage; a resistor having a first terminal connected to a second terminal of the switch; a capacitor having a first terminal connected to a second terminal of the resistor and having a second terminal connected to the reference voltage; and a controller having an input voltage supply terminal connected to the first terminal of the capacitor and a second terminal connected to the reference voltage, having a first input connected to the first terminal of the battery, having a second input connected to the first terminal of the capacitor, having a first output connected to a third terminal of the switch, and having a second output connected to voltage dividers for the first and second inputs of the controller. ### Claim 2 (depends on 1) The system of claim 1, wherein: the switch is turned on with a signal from the controller when the voltage of the capacitor is below a first voltage limit; and the switch is turned off with a signal from the controller when the voltage of the capacitor is above a second voltage limit. ### Claim 3 (depends on 2) The system of claim 2, wherein when the switch is on, the charge current is proportional to a voltage across the resistor that is connected between the switch and the capacitor. ### Claim 4 (depends on 3) The system of claim 3, wherein current consumption is calculated at the controller from the voltage measured across the resistor that is connected between the switch and the capacitor, a value of the resistor, and a duty cycle of the switch. ### Claim 5 (depends on 3) The system of claim 3, wherein the charge current at the first terminal of the capacitor is within a predefined range as given by the first and second voltage limits and a value of the resistor for a current that can be measured within a predetermined tolerance relative to a calculated value based on components of the system. ### Claim 6 (depends on 4) The system of claim 4, wherein: when the battery is being discharged, internal resistance of the battery increases or the voltage of the battery decreases, which results in an increase of the duty cycle; an amount of discharge of the battery is detected by a measurement of the duty cycle; and when the duty cycle reaches between 90 percent and 100 percent, the battery approaches being empty but has sufficient charge for a predetermined time period as indicated by an amount of current draw from the battery by an instrument for which the battery is providing power. ### Claim 7 (depends on 2) The system of claim 2, wherein the second voltage limit restricts a voltage to the input voltage supply terminal of the controller, up to an amount that is still harmless to the controller. ### Claim 8 A method for controlling voltage and measuring current, comprising: connecting a first terminal of a switch to a first terminal of a resistor; connecting a second terminal of the resistor to a first terminal of a capacitor; connecting a second terminal of the capacitor to a ground terminal; connecting a first power terminal of a controller to the first terminal of the capacitor and a second power terminal of the controller to the ground terminal; connecting a first input terminal of the controller to a second terminal of the switch, a second input of the controller to the first terminal of the capacitor; connecting a first output of the controller to a control terminal of the switch, and a second output of the controller to the second terminal of the switch; and connecting a first terminal of a battery holder or connector to the second terminal of the switch, and a second terminal of the battery holder or connector to the ground terminal. ### Claim 9 (depends on 8) The method of claim 8, further comprising inserting a battery in the battery holder or connector with a positive terminal of the battery connected to the first terminal of the battery holder or connector and a negative terminal of the battery connected to the second terminal of the battery holder or connector. ### Claim 10 (depends on 9) The method of claim 9, wherein the switch is a P-channel FET having a drain as the first terminal of the switch, a source as the second terminal of the switch, and a gate as the control terminal of the switch. ### Claim 11 (depends on 10) The method of claim 10, further comprising: connecting a pull-up resistor across the source and the gate of the FET: inserting a first voltage divider at the first input terminal of the controller; and inserting a second voltage divider at the second input terminal of the controller. ### Claim 12 A battery charge detection circuit comprising: a battery receptacle having a first terminal for connection to a positive terminal of a battery and a second terminal for connection to a negative terminal of the battery; a switch having a first terminal connected to the first terminal of the receptacle, and having a second terminal and a third terminal; a resistor having a first terminal connected to the third terminal of the switch and having a second terminal; a capacitor having a first terminal connected to the second terminal of the resistor, and having a second terminal connected to a ground terminal and to the second terminal of the battery receptacle; and a controller having a first power terminal connected to the first terminal of the capacitor and a second power terminal connected to the ground terminal, having a first input terminal connected to the first terminal of the switch, having a second input terminal connected to the first terminal of the capacitor, having a first output connected to the second terminal of the switch, and having a second output connected to the first terminal of the switch. ### Claim 13 (depends on 12) The circuit of claim 12, further comprising a battery inserted or situated in the battery receptacle with connections made between the first terminal of the battery receptacle and the positive terminal of the battery, and between the second terminal of the battery receptacle and the negative terminal of the battery. ### Claim 14 (depends on 13) The circuit of claim 13, wherein: the switch is turned on when the voltage at the first terminal of the capacitor relative to the ground is below a first predetermined voltage limit; and the switch is turned off when the voltage at the first terminal of the capacitor is above a second predetermined voltage. ### Claim 15 (depends on 14) The circuit of claim 14, wherein: when the switch is on, a voltage between the first and second terminals of the resistor is measured; and the voltage measured is proportional to a charge current at the capacitor. ### Claim 16 (depends on 15) The circuit of claim 15, wherein the voltage measured divided by the resistance of the resistor indicates an amount of charge current to the capacitor. ### Claim 17 (depends on 16) The circuit of claim 16, wherein an average current consumption is determined by the amount of charge current and a duty cycle of the switch. ### Claim 18 (depends on 16) The circuit of claim 16, wherein the charge current is constrained to a predefined range according to the first predetermined voltage and the second predetermined voltage. ### Claim 19 (depends on 18) The circuit of claim 18, wherein the amount of charge current is measured with an accuracy within a range of plus and minus five percent of a verified actual value. ### Claim 20 (depends on 17) The circuit of claim 17, wherein: when the battery is discharged, its internal resistance increases and thus the duty cycle of the switch increases; and measuring the duty cycle as it becomes one hundred percent leads to an indication that the battery is almost totally discharged but at that moment the battery can be exchanged for a battery having more charge before the power available becomes insufficient for a supported circuit or instrument to function or operate.