Battery Open-Circuit Voltage Measurement Before Boot-Up Loading
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Solution Overview
Problem
Conventional fuel gauging algorithms in battery-powered devices inaccurately measure open circuit voltage (OCV) due to loading the battery during the boot-up sequence, leading to significant state of charge (SoC) estimation errors.
Innovation Solution
Sample the OCV of the battery before boot-up and hold it until the device is fully loaded, using a sample-and-hold circuit and an analog-to-digital converter to digitize the voltage for accurate SoC estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the battery is loaded during the boot-up sequence to power the device, then the device can operate, but the open circuit voltage measurement becomes inaccurate due to voltage drop under load
Solution Approach 1:
The patent measures the battery voltage before the boot-up sequence loads the battery, capturing the open circuit voltage when no current is drawn. This preliminary measurement occurs at a specific timing point during power-on before any device components are activated, ensuring the voltage reading reflects the true battery state without load-induced voltage drop.
Solution Approach 2:
The patent introduces a timing mechanism as an intermediary between battery loading and voltage measurement. By controlling the measurement to occur at a specific time window during the power-on sequence, the system mediates between the need to load the battery for operation and the need to measure voltage under no-load conditions, capturing the voltage at the optimal moment before significant current draw occurs.
2Ease of operation
If the battery voltage is measured after loading to enable device operation, then the device can function, but significant state of charge estimation errors occur
Solution Approach 1:
The system performs the voltage measurement action preliminarily, before the battery is loaded with device current demands. The measurement is captured during the initialization phase when the battery is still in a relatively unloaded state, ensuring that the voltage reading accurately reflects the battery's true state of charge before operational loads cause voltage depression.
3Duration of action of moving object
If conventional fuel gauging algorithms measure battery voltage during normal operation, then continuous monitoring is achieved, but the measurements reflect loaded voltage rather than true open circuit voltage
Solution Approach 1:
The patent implements periodic voltage measurements at specific intervals during device operation, particularly during wake-up transitions or idle periods when the battery load is minimized. This periodic sampling approach allows the system to capture open circuit voltage readings at appropriate moments while maintaining continuous monitoring capability through regular measurement cycles.
Data Source
AI summary
Techniques and apparatus for accurately measuring an open circuit voltage of a battery included in a battery-powered device are provided. One example apparatus generally includes a sample-and-hold circuit configured to sample a voltage of a battery before loading the battery and to hold the sampled voltage of the battery; an analog-to-digital converter (ADC) selectively coupled to an output of the sample-and-hold circuit and configured to digitize the held voltage of the battery; and a controller configured to enable the ADC for digitizing the held voltage of the battery after the sample-and-hold circuit samples the voltage of the battery.