Auxiliary Battery Disconnect Detection in Stop-Start Systems
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Solution Overview
Problem
Conventional automatic stop-start engine systems lack the ability to detect a disconnected auxiliary power source without additional hardware, which can disrupt power and prevent engine restarts.
Innovation Solution
A system and method that utilize a power control relay and an engine control module (ECM) with an algorithm to isolate the auxiliary power source from the primary power source, allowing the ECM to determine if the auxiliary power source is disconnected by temporarily isolating it and checking for power loss, thereby enabling detection and disabling auto-stop events until the issue is serviced.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the auxiliary power source is disconnected, then the system cannot detect the disconnection without additional hardware, but the disconnected auxiliary power source disrupts power to vehicle modules and prevents the autostart event
Solution Approach 1:
The system uses its existing controller and power control relay to perform the detection function, rather than requiring separate dedicated detection hardware. The controller activates the power control relay to isolate the auxiliary power source and monitors itself for power loss, enabling the system to self-diagnose the auxiliary battery connection status using components already present in the stop-start system.
2Difficulty of detecting and measuring
If additional hardware is added to detect auxiliary power source disconnection, then detection capability is improved, but device complexity increases
Solution Approach 1:
The existing controller performs the detection function by monitoring its own power status after isolating the auxiliary power source through the power control relay, eliminating the need for separate detection sensors or additional hardware components.
Solution Approach 2:
The power control relay, originally designed for power management functions in the stop-start system, is also utilized for isolation during detection. The controller serves multiple roles including normal engine management and auxiliary battery disconnect detection, reducing the need for dedicated single-function components.
3Measurement precision
If the power control relay is activated to isolate the auxiliary power source, then the controller can detect disconnection, but power is temporarily disrupted to the controller
Solution Approach 1:
The controller activates the power control relay to isolate the auxiliary power source before performing the detection check. By preparing the isolation condition in advance and then monitoring its own power status, the controller can accurately determine auxiliary battery connection status without requiring continuous power disruption.
Data Source
AI summary
A system for controlling an automatic engine stop-start system of a vehicle includes a controller, an engine configured to be automatically stopped and started in response to a signal from the controller, a primary power source electrically coupled to the controller, and an auxiliary power source electrically coupled to the controller. A power control relay is electrically connected between the primary power source and the auxiliary power source and is configured to be selectively activated to isolate the auxiliary power source from the primary power source such that only the auxiliary power source is configured to supply power to the controller. The controller is configured to determine if the auxiliary power source is electrically disconnected from the vehicle when the power control relay is activated.