Battery-Powered HVAC Sensor Mesh Routing to Reduce Sleep Current Draw
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Solution Overview
Problem
Existing wireless HVAC systems face challenges with high installation costs due to hard-wiring, limited battery lifespan in wireless devices, and increased manufacturing costs due to the need for various device versions with user interfaces, which affect reliability and efficiency.
Innovation Solution
A method and circuit for detecting excessive sleep current draw in battery-powered HVAC devices using a MOSFET and transistor configuration to generate interrupts, and an energy-efficient mesh network method for data transmission that minimizes wake/sleep cycles and delegates route determination to routers, along with a kit for manufacturing HVAC sensors with reversible printed circuit boards for exposed or hidden displays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If wireless HVAC devices use batteries to eliminate hard-wiring, then installation cost and complexity are reduced, but battery lifespan is limited and requires periodic maintenance
Solution Approach 1:
The system enables self-service through automatic mesh network routing where intermediate nodes autonomously forward data packets without human intervention. The sleep current detection circuit automatically monitors and alerts when batteries need replacement, eliminating the need for manual system management and reducing maintenance burden.
Solution Approach 2:
The sleep current detection circuit performs preliminary monitoring of battery health by continuously measuring voltage drops during sleep mode. This early detection mechanism identifies potential battery failures before they occur, allowing proactive maintenance scheduling and preventing system outages.
2Use of energy by moving object
If battery-powered devices enter sleep mode to conserve energy, then power consumption is reduced, but excessive sleep current draw can occur undetected
Solution Approach 1:
The sleep current detection circuit implements continuous feedback monitoring by measuring voltage drops across the battery during sleep mode. When the voltage drop exceeds a threshold indicating excessive current draw, the system generates an alert signal to notify the microcontroller, enabling real-time correction of power management issues.
3Reliability
If mesh network nodes transmit data frequently to ensure reliability, then data delivery is improved, but power consumption increases
Solution Approach 1:
The system employs periodic transmission cycles where battery-powered end nodes transmit data packets at scheduled intervals rather than continuously. The mesh network routers buffer and forward these periodic transmissions, ensuring reliable data delivery while allowing end nodes to remain in low-power sleep mode between transmission cycles.
4Reliability
If end nodes remain awake to receive acknowledgments, then communication reliability is improved, but battery life is reduced
Solution Approach 1:
Routers in the mesh network perform preliminary actions by buffering outgoing data packets and proactively transmitting them to destination nodes before the end node wakes up. This eliminates the need for end nodes to remain awake waiting for acknowledgments, as the network infrastructure handles delivery timing and confirmation.
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
The solution extends battery life, reduces manufacturing costs, and enhances reliability by detecting excessive current draw, optimizing mesh network efficiency, and providing flexible display configurations for HVAC sensors, thereby improving overall system performance and cost-effectiveness.
Implementation Method 1
measuring a voltage drop across a MOSFET device coupled in a forward-conducting orientation in series between the battery and the microcontroller
Implementation Method 2
causing a transistor to conduct when the voltage drop exceeds a predetermined threshold to generate a first trigger signal
Data Source
AI summary
HVAC components having improved efficiency are described. In one embodiment, excessive sleep current draw in a battery-powered device having a microcontroller is detected by measuring a voltage drop across a MOSFET device coupled in a forward-conducting orientation in series between the battery and the microcontroller, causing a transistor to conduct when the voltage drop exceeds a predetermined threshold to generate a first trigger signal, integrating the first trigger signal to generate a second trigger signal, and generating an interrupt to the microcontroller. In another embodiment, a battery-saving method of operating an HVAC component includes maintaining the HVAC device in the sleep mode, receiving a user input to wake the device, transmitting a data request and returning the HVAC component to the sleep mode, waking up the HVAC device to poll an adjacent network node storing a cached response, displaying the response, and returning the HVAC device to sleep.