Wireless Audio Battery Pre-Charging Circuit
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Solution Overview
Problem
Wireless audio devices, particularly those with NiMH batteries, face issues with inconsistent voltage measurements due to aging, leading to incorrect charging activation and power depletion, which prevents effective charging.
Innovation Solution
A portable charging case with charging circuitry that pre-loads the device battery with a resistive load to accurately determine voltage and applies a constant pre-charging voltage if the battery voltage is below a certain threshold, switching to standard charging mode once the voltage is raised above the undervoltage lockout value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If standard charging mode is activated based on voltage measurement, then charging can proceed efficiently, but voltage measurements become inaccurate due to battery aging and inconsistent readings
Solution Approach 1:
The patent applies preliminary action by performing a pre-charge operation before standard charging. The charging case first applies a pre-charging voltage to bring the battery voltage above the undervoltage lockout threshold, ensuring accurate voltage measurements before initiating standard charging mode. This preliminary step resolves the measurement accuracy issue that would otherwise prevent efficient charging.
2Measurement precision
If pre-charging mode is applied to all batteries, then voltage measurement accuracy improves, but charging time increases due to additional pre-charge step
Solution Approach 1:
The patent applies dynamics by making the charging mode adaptive rather than static. The system dynamically switches between pre-charging mode and standard charging mode based on the measured battery voltage. If voltage is above the undervoltage lockout threshold, standard charging is applied directly; if below, pre-charging is applied first. This dynamic approach optimizes charging time while ensuring measurement accuracy when needed.
3Reliability
If undervoltage lockout threshold is set high, then device functionality is maintained, but batteries with aging show inconsistent voltages preventing charging activation
Solution Approach 1:
The patent applies preliminary action by implementing a pre-charging step that raises battery voltage above the undervoltage lockout threshold before standard charging begins. This preliminary action enables the system to maintain a high undervoltage lockout threshold for device functionality while still being able to charge aged batteries that would otherwise show inconsistent voltages below the threshold.
Solution Approach 2:
The patent applies parameter changes by introducing a pre-charging voltage parameter that is higher than the standard charging voltage. This temporary parameter change allows the battery voltage to be raised from below the undervoltage lockout threshold to above it, enabling subsequent standard charging to proceed while maintaining the original high threshold for device functionality.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Ensures accurate voltage determination and pre-charging of NiMH batteries, preventing power depletion and enabling effective standard charging, thus maintaining device functionality and safety.
Implementation Method 1
applying, via the device microcontroller, a pre-charge load to the device battery
Implementation Method 2
charge the device battery, via the power transfer connection, in pre-charging mode
Data Source
AI summary
A portable charging case is provided. The case includes a charging interface configured to establish a power transfer connection with a wireless audio device having a battery. The case includes charging circuitry configured to determine a voltage of the battery. The charging circuitry is further configured to, if the voltage is less than or equal to an undervoltage lockout, charge the battery in pre-charging mode. In pre-charging mode, the charging circuitry is configured to apply a constant pre-charging voltage to the battery. The charging circuitry is further configured to switch from pre-charging mode to standard charging mode when the voltage exceeds the undervoltage lockout value. The charging circuit is further configured to determine the voltage by (1) powering on, via a case power source, the wireless audio device; (2) applying, pre-charge load to the device battery; (3) retrieving the voltage; and (4) transmitting the voltage to the case.