Pressure Measurement Techniques for EV Batteries

Battery design with external pressure sensor to improve thermal runaway detection. The battery has cell modules, a main control unit, and a pressure sensor outside the main board, like near the switch box or on a secondary board. This allows better thermal event detection without enlarging the main board. A nearby temperature sensor on a cell board completes the setup. The external sensor avoids board size issues, improves data verification, and enables closer proximity to cells for better thermal event detection.

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Accurately measuring internal pressure of secondary batteries like lithium-ion batteries to improve safety and reliability by directly measuring the pressure instead of indirectly through gas injection. The method involves inserting a pressure sensor between the battery and lower plate, monitoring the sensor's reading as gas is injected into the battery, then measuring the sensor value when venting releases pressure. This directly measures the internal battery pressure instead of relying on gas injection.

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Estimating pressure distribution inside a battery cell during pressure testing to evaluate uniform pressing. The method involves measuring strains using sensors on the pressure apparatus as it compresses the cell. The strains are used to estimate the pressure distribution inside the cell rather than just the average pressure. This allows analysis of localized pressure imbalances and identification of causes.

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A flexible printed circuit board (FPC) for measuring the internal pressure of pouch-style lithium-ion battery cells. The FPC has a pressure sensor mounted on an extension part that extends from the sensing part to the board. The extension part has a metal protective sheath surrounding the insulation. This allows the FPC to be inserted into the gas pocket inside the pouch cell without cutting or damaging the insulation. The sheath seals against the cell outer layers during welding to enclose the sensor. The FPC can then accurately measure the cell's internal pressure during charging and discharging.

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A battery cell monitoring system that provides direct measurement of electrical, pressure, and temperature distributions inside a battery cell to improve battery design and charging. The system involves a segmented current collector array with uniform or varying density of current collectors directly contacting the cell electrode. Temperature sensors, pressure sensors, and reference electrodes are also collocated on a PCB. This allows capturing localized current, impedance, and temperature data during cell operation to understand distribution patterns and locate potential faults. The isolated data bus and controller capture the signals from the arrays without connecting to the cell electrodes.

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Battery module for electric vehicles with improved thermal runaway prevention using pressure sensing and cooling system adjustment. The module has a sensing pad on the cell sidewall connected to a battery management system (BMS). The BMS receives cell pressure measurements. If pressure exceeds a threshold, indicating swelling, it reduces cooling water flow rate to prevent overheating. This prevents cell damage and runaway from pressure buildup during charging/discharging cycles.

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Leak detection system for checking the tightness of objects like batteries by measuring pressure variations. The system involves pressurizing the object's internal space, measuring pressure inside and outside, and calculating leak size based on normalized pressure differences. The system uses multiple pressure sensors inside and outside the object, along with temperature sensors, to accurately determine leaks even in environments with large pressure and temperature variations. The normalized pressure differences account for environmental effects on the internal pressure. This allows more reliable and repeatable leak detection in industrial environments where object temperatures and pressures can fluctuate.

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Early and accurate detection of thermal chain (thermal runaway) in battery packs to improve safety. The method involves monitoring both cell voltage and pack pressure, and determining thermal chain when both are abnormal. This prevents false positives from just cell voltage issues, and accounts for pressure contributors like leaks or exhaust gas. If pack pressure or cell voltage becomes abnormal, it's monitored for a set time even if values return to normal to catch short-lived thermal chain events.

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Detecting abnormal battery operating conditions that could lead to thermal runaway in electric vehicle battery packs. The detection method involves using a pressure sensor in the cooling circuit and a battery management system (BMS). When the coolant flow is stopped, the pressure increase indicates evaporation due to hotspots from failing cells. If the pressure jump exceeds a threshold, it indicates overheating that could cause runaway. This provides higher sensitivity for detecting hot cells compared to just monitoring cell temperatures.

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Accurately measuring the swelling pressure of battery cells to prevent module deformation and improve safety. Multiple pressure sensors are arranged on the surfaces of the battery cells in a grid pattern. The sensors are connected together and output the summed pressure value. This allows comprehensive coverage of the cell surfaces to accurately measure overall swelling pressures. The sensors transmit the pressure data to a battery management system for monitoring. As resistance decreases indicating stronger swelling, the signal type changes to warn of increasing danger levels.

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Detachable pressure measuring units to accurately inspect the swelling of batteries without restriction or dispersion of pressure. The units have a body with an upper surface, a pressure sensor on the upper surface, and a connector on a side. The units can be attached to a fixed frame surrounding a battery to measure localized swelling pressures. Multiple units connected to a receiver collect and transmit the pressure data. A central processor aggregates the data to determine overall battery swelling and pressure distribution.

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Apparatus for accurately measuring the swelling pressure of battery cells to improve safety and performance of battery modules and packs. The apparatus has a pressure sensor array contacting the cell surface and a plate between the cell and sensors. This ensures uniform pressure distribution across the cell surface. The sensors are connected and summed to provide an overall cell swelling pressure. The sensors transmit data to a BMS for monitoring. As cell swelling increases, the resistance of the sensors decreases, indicating more pressure and potentially imminent cell failure.

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A battery case leak detection device for electric vehicles that can test the integrity of the battery enclosure without introducing contaminants. The device connects to the battery case service port and applies a pressure to the enclosure volume. A pressure sensor measures any decay. If decay exceeds a threshold, it indicates a leak. The device has a pre-test mode to quickly check for large leaks before the main test. This allows avoiding unnecessary testing if a large leak is found.

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A system and method to locally identify degradation in a secondary battery like a lithium-ion battery. It involves installing multiple pressure sensors on the battery surface and using them to determine degradation. The sensors detect pressure at specific locations. By analyzing the sensor readings, the system estimates the position of maximum volume expansion on the battery surface, indicating the degradation location.

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Early detection of thermal runaway in battery cells of electric vehicle traction batteries by monitoring the pressure inside the battery housing. The pressure inside the housing is continuously monitored using a pressure sensor connected to the battery management system. If the pressure exceeds a threshold or falls outside a range, it indicates a critical state like thermal runaway in the cells. This allows proactive mitigation of cell failures and potential fires by detecting runaway at an early stage.

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Controlling charging of a battery module to extend its cycle life by adjusting charge cutoff voltages based on internal pressure. A pressure sensor on the battery module measures the internal pressure. Based on predefined charge cutoff voltages and pressure thresholds, the optimal charge cutoff voltage for the current pressure level is determined. This allows customizing the charge cutoff voltage as the internal pressure increases to avoid deterioration and extend cycle life.

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Detecting battery aging in cell-to-pack lithium-ion batteries by measuring pressure between the battery cells and housing. Pressure sensors are installed between the battery cells and housing walls to detect the mechanical pressure between them. This pressure increases as the cells expand due to aging. The sensor data is sent to the battery management system to monitor cell aging and identify functional errors.

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Monitoring battery degradation in a battery pack to detect and prevent swelling and expansion. The method involves periodically discharging the battery pack and measuring the internal resistance to detect if it exceeds the initial resistance. If so, it indicates degradation and swelling. A pressure sensor monitors pack pressure. If above a threshold, it discharges the pack again. If the resistance still increases, an alert is sent. This proactive discharge and resistance monitoring catches degradation earlier than capacity loss from a fuel gauge.

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Detecting thermal runaway in electric vehicle batteries to warn occupants of potential fire hazards. The system uses pressure sensors inside the battery cells to detect swelling and gas generation that indicate thermal runaway. When runaway is detected, an alarm notifies the occupants of the potential danger. This allows early warning and evacuation before a battery fire spreads.

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Accurately evaluating airtightness of a vehicle case like a battery pack by compensating for deformation-induced pressure measurement errors. The method involves pressurizing/depressurizing the case, measuring pressure change, acquiring deformation at specific locations, correcting pressure change based on deformation, and evaluating airtightness using the corrected pressure change. This compensates for case deformation during pressure measurement that can affect accuracy. The deformation locations with larger pressure-induced deformation are identified and used for correction.

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