Tesla's Thermal Management Techniques for EV Batteries

A system for providing coolant ingress into an electric vehicle battery pack during internal thermal events to mitigate chain reactions. The system has a fill port access mechanism that allows water or other coolant to be directed into the battery pack through a breach made in the enclosure wall. The breach is created using a specialized tool that pierces the enclosure without damaging it. This allows responders to introduce coolant into the pack during emergencies where the normal fill port is unavailable. The breach is sealed after coolant ingress to prevent ongoing ingress.

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Integrating a battery pack into an electric vehicle to improve protection, noise insulation, thermal insulation, and vibration damping compared to traditional mounting methods. The battery pack enclosure is mounted between the vehicle floor and the road. An insulating layer is placed between the enclosure and the floor to isolate noise, heat, and vibrations. The insulating layer compresses when the enclosure is mounted to the vehicle. The insulating layer can have properties like high acoustic isolation, low thermal conductivity, and high temperature resistance. Materials like silica fibers, alumina, or calcium-magnesium-silicate fibers can be used.

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Battery pack design to mitigate thermal runaway hazards in electric vehicle batteries. The battery pack has multiple sealed compartments, each with a vent assembly containing an elastomeric valve. Under normal conditions, the valves seal the compartment exhaust ports. But if a battery inside overheats, the valve cracks open to vent hot gases safely through an exhaust guide. This prevents pressure buildup, compartment failure, and spontaneous ignition. The pack enclosure also has a lower-pressure equalization valve to balance compartment pressures. This prevents catastrophic pack rupture if one cell fails.

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System to mitigate risks during battery pack thermal runaway in electric vehicles. The system has a failure port in the pack enclosure that stays closed during normal operation but opens during runaway. This allows hot gas to escape instead of building up pressure. The port has a thinner weaker section that fails first, preventing the whole enclosure from melting. The enclosure material has high melting point layers to contain runaway heat. A channel directs exhaust away from passenger compartment. Insulation and fire retardant layers further protect.

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A system for safely cooling high-energy battery packs during thermal runaway events to prevent chain reactions and explosions. The system allows water ingress into the battery enclosure through a selectively permeable fill port. The port has an obstruction that allows water to enter while preventing gas escape. This allows controlled water flooding of the battery pack to cool overheated cells and stop runaway reactions. The fill port is positioned clear of hot gases. The enclosure is reinforced to protect against mechanical damage.

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Automated low temperature fast charging system for lithium-ion batteries that enables fast charging at cold temperatures without risk of lithium plating damage. The system monitors critical parameters periodically and dynamically scales the charging rate based on those parameters. If the parameters allow, it uses a high rate charging process. If not, it uses a slower rate charging process that won't cause plating. This allows charging at low temperatures without disabling fast charging.

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Detecting and responding to exceptional charge events in series-connected battery packs to prevent overcharge and overdischarge in individual cells. The method involves detecting exceptional charge events using different modalities for steady state and transient charging conditions. Steady state detection involves analyzing statistical parameters over time. Transient detection looks for deviations in cell characteristics during fast charge/discharge. Responses to exceptional charge events include preventing further charging, increasing cooling, and limiting future charging.

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Detecting and remediating exceptional charge states in individual battery elements of a multi-element battery pack to prevent overcharging and overdischarging. The method involves monitoring charge-dependent parameters of each battery element during operation to establish a normal charge characteristic pattern. An exceptional charge event is detected when a battery element's charge pattern deviates from normal during a time segment where it should match. This indicates an imbalance that could lead to overcharge or overdischarge. Responses include preventing charging, increasing cooling, or limiting future charging to prevent further imbalance.

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Detection and remediation of exceptional charge events in series-connected battery packs to prevent overcharge and overdischarge of individual cells. The system uses two detection modalities: one for overall charge imbalance and another for exceptional charge events in specific cells. Responses include reducing charge imbalance, limiting charging, increasing cooling, and preventing further charging for overdischarge events. The dual detection and customized responses address exceptional charge events that can bypass normal balancing systems due to measurement errors.

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Early identification of an impending fast-charge opportunity for battery packs in electric vehicles and using that information to prepare the batteries for fast-charging. The system predicts if an upcoming charge will be fast or slow, and adjusts the battery temperature profile accordingly. For fast charging, the temperature is raised above the standard operating temperature to improve performance. For slow charging, the temperature is lowered to preserve lifetime. This allows optimizing battery temperature for specific charge rates.

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System for thermally conditioning an electric vehicle's battery pack during charging to maintain optimal temperature. The system involves providing external cooling or heating to the battery pack while charging, based on information received from the vehicle about its battery temperature. This allows customized thermal management during charging, which can be different from driving conditions. The external cooling/heating can be provided using a separate fluid loop with an arm extending into the vehicle to connect to the battery pack. This allows more targeted thermal conditioning compared to relying solely on the vehicle's internal cooling system.

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Battery charger and charging process for low temperature charging of lithium-ion batteries to extend charging profiles below freezing without degrading cycle life. The charging system uses an adjustable voltage profile with a variable low temperature charging stage. The profile includes a non-low temperature stage for charging above freezing and a low temperature stage with decreasing charging current below freezing to prevent capacity loss. The profile is determined using an imaginary resistance component based on cell temperature. This compensates for resistance increases at low temperatures to maintain charging performance below freezing.

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Optimizing battery performance in electric vehicles by dynamically controlling battery temperature to improve power, extend life, and mitigate degradation. The system measures battery impedance at different temperatures and determines the optimal temperature for minimum impedance. It preheats the battery to that temperature for high performance driving modes. For normal driving, it maintains the battery at an optimal temperature. During storage, it brings the battery to a target storage temperature. This prevents overheating for performance, keeps it cool enough for longevity, and avoids degradation at extreme temperatures.

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Battery charging system for electric vehicles that heats the battery during charging to improve charging efficiency in cold temperatures. The system compares the battery voltage to a line voltage offset calculated based on a voltage level added to the line source voltage. If the battery voltage is less than the offset, a heating element is connected in series with the charging source to heat the battery fluid. If the battery voltage is above the offset, the heating element is bypassed. This prevents overheating the battery when already warm, while providing heat assist during cold charging.

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Integrated battery pack heat exchanger system for electric vehicles that provides efficient heat transfer while utilizing vehicle surfaces. The system involves integrating the heat exchanger into the battery pack enclosure that is mounted under the vehicle floor. The heat exchanger conduits are thermally coupled to the inside surface of the enclosure base plate. When the thermal management system configures the system into the first operational mode, the heat exchanger is coupled to the batteries. In the second operational mode, it is decoupled. This allows the base plate exposed to ambient air flow during vehicle motion to act as a large heat transfer surface. A blower fan can be used to direct air over the base plate.

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A compact and efficient cooling solution for battery packs in electric vehicles. The cooling uses heat pipes with flat evaporators that contact the cell second ends. The cells are arranged with aligned second ends to maximize contact between the heat pipes and cells. This provides direct heat transfer from the cells to the heat pipes without intermediary cooling fluid. The heat pipes can then transfer the heat to an external heat sink or radiator. This eliminates the need for cooling fluid connections inside the battery pack and simplifies cooling system design.

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An automotive thermal management system with improved cooling efficiency and reduced fan power compared to stacked heat exchangers. The system has multiple heat exchangers arranged in a non-stacked configuration with separate inlets and adjustable louvers. An airflow duct connects some heat exchangers. Louvers control airflow between heat exchangers in the duct. This allows optimized cooling by selectively routing air based on temperature and need. It prevents hotter upstream air affecting downstream heat exchangers. The non-stacked layout reduces overall fan power by avoiding ducting air through all exchangers.

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Battery pack design for electric vehicles that improves pack cooling and life by reducing heating during charging and discharging. The design involves a unique cell-to-cell interconnection tab configuration that provides improved heat conduction between cells to help equalize temperatures. The tabs are sized to balance conductivity and mechanical integrity. This reduces hot spots and improves pack cooling compared to conventional tab designs. By equalizing cell temperatures, it improves battery life.

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Battery cooling system that improves manufacturability and performance of battery packs for electric vehicles. The cooling system uses a thermal interface layer between cooling tubes and battery rows. The layer has pliable fingers that deflect and contact the battery cells. This allows the tubes to be closer to the cells for better cooling without risk of shorting. The fingers also reduce forces on the tubes during pack assembly. The interface layer has properties like high dielectric strength, thermal conductivity, and low friction. It can be attached to the tubes using adhesive.

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Air supply system for vehicles with vents that provide targeted airflow without needing multiple vents per passenger. The system uses vents with high aspect ratios to generate wide, planar air streams. To control the direction of these streams, secondary vents are placed downstream to intersect with the primary streams. This allows manipulating the main streams by feeding low pressure zones or pushing them away. This provides better control over the airflow when the primary vents are mounted non-flush. The high aspect ratio vents also reduce air sticking to nearby surfaces.

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A system for arranging multiple batteries in a stable and resilient configuration to improve reliability, thermal management, and packing density compared to stacking batteries. The batteries are sandwiched between rigid substrates to distribute force and prevent crushing. Conductors draw power and connect the batteries in parallel/series. Holes in the substrates prevent shorting. Cooling channels run between the batteries and adjacent tubes flow in opposite directions to maintain constant temperature.

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A clamshell battery housing with integrated cooling channels to improve thermal efficiency and simplify manufacturing compared to separate cooling components. The housing has depressions to hold the battery cells and walls defining integrated cooling channels for circulating coolant directly contacting the cell sides and ends. This eliminates the need for separate cooling components between cells, reducing resistance and contact points. The housing also allows stacking of modules without external manifolds.

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Passive air removal from a liquid cooling manifold to prevent gas accumulation and improve cooling effectiveness. The system uses a bleed structure with a channel connecting the manifold to an area outside the sealed housing. The channel has one end in the manifold where air accumulates due to buoyancy and the other end in an area with lower pressure. The pressure differential causes the air to move passively through the channel and exit the housing, preventing it from interfering with cooling. This allows air to be removed from the manifold without active purging or changes to the cooling circuit layout.

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A battery cooling system with improved manufacturability for battery packs. The cooling system uses a contoured manifold assembly with a dual layer thermal interface. The manifold has coolant channels matching the cell row curvature. The inner layer of the interface is compressible silicone with low modulus and high thermal conductivity. The outer layer is a dielectric material with high breakdown voltage, tear resistance, low friction, and flexibility. This allows easy insertion between cells and coolant channels without shorting. The compressible inner layer conforms to cell shapes and the outer layer seals against cells while allowing coolant flow. The dual layer interface improves manufacturability by eliminating the need for custom thermally conductive interfaces between cells and coolant channels.

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Thermal management system for batteries to mitigate the risks and hazards of thermal runaway events. The system has an exhaust nozzle that directs hot gas out of the battery pack during a runaway. A seal retains the nozzle closed during normal operation. An SMA retaining member captures the seal and seals the nozzle. During a runaway, the SMA transforms and releases the seal, allowing it to eject and open the nozzle for controlled exhaust. This prevents internal pressure buildup and prevents gas release into the pack. The SMA activation can be passive or active heating.

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System to mitigate the effects and hazards of battery thermal runaway by controlling the egress of hot gas and debris. It involves a sealed battery pack with an exhaust port and valves that unseal during runaway pressure. A valve retention plate covers the port and has retention plate ports. Elastomeric valves seal the plate ports normally. During runaway, the hot gas melts and ejects the plate, unsealing the exhaust port. An angled duct inside the pack directs the expelled hot gas and debris away from the battery pack. This aims to prevent collateral damage and propagation by guiding the ejecta away from the pack and vehicle.

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Thermal management system for mitigating the effects of thermal runaway in battery packs. The system uses an airtight enclosure with cavities in the sides and a removable exhaust port cover. During normal operation, the cavities are sealed. If a battery venting gas, it enters the cavities and is directed out through the open exhaust port. This prevents gas from escaping into the pack interior or enclosure, reducing the risk of spontaneous combustion. The exhaust port can be a cap with a melting valve or cover that seals normally but opens during high pressure. The cavities can also have internal barriers to isolate groups of batteries. This allows thermal energy to flow between them, preventing propagation. The pack is also coupled to an external thermal mass to absorb and radiate heat from the cavities.

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Battery design to prevent thermal runaway propagation in multi-cell battery packs. The battery assembly has a layer of intumescent material applied directly to the cell casing walls and bottom, except around contact points with the cell cap. The intumescent material absorbs heat and expands when it reaches a certain temperature during cell overheating. This delays perforation and provides a barrier to prevent thermal runaway from spreading to adjacent cells. The intumescent coating also contains escaping gas and directs heat away from the cell.

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Battery pack design that mitigates the risks of thermal runaway propagation in case of an internal short circuit. The battery pack has a preselected cell that is thermally isolated from the other cells. The preselected cell has a higher temperature internal short circuit safety mechanism than the other cells. This allows current to be safely interrupted in the preselected cell at a higher temperature than the other cells. The thermal isolation prevents excessive heating from spreading to the other cells. The isolation can be an enclosure with materials like ceramic, intumescent coatings, or phase change materials.

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Containing thermal runaway in battery packs to prevent cascading failures and minimize damage and hazards. The pack is divided into multiple cell groups using thermal barrier elements. These elements prevent thermal runaway in one group from propagating to adjacent groups. The barriers have high melting points, low thermal conductivity, and can contain cooling fluid. They can be sandwiched layers or central regions. This limits thermal spread if a cell group fails, reducing pack and collateral damage.

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Preventing thermal runaway propagation in battery packs by using spacers between cells to maintain their separation and position during thermal events. The spacers are rigid, insulating, and have a higher melting point than the cell mounting brackets. They prevent cell movement and collapse when brackets melt during runaway, which can bridge cells and conduct heat. The spacers are independent from the brackets and fit between cells to keep them spaced and prevent runaway propagation.

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Battery design to prevent cell-to-cell propagation of thermal runaway. The design involves adding a pre-formed secondary can around the battery cell case that inhibits gas escaping through the cell walls during thermal runaway. The secondary can is made of high yield strength materials that resist perforation. This forces gas to exit through the cell ends instead of side walls, reducing collateral damage.

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Center pin for battery cells that improves thermal behavior during thermal runaway to prevent cell rupture and propagation of thermal events. The center pin is made of an intumescent material that expands and swells when heated above a certain temperature during thermal runaway. This expansion helps absorb and contain the internal pressure and prevent cell rupture. The intumescent material can fill the pin void or cover the pin surface. A secondary non-intumescent material may surround the intumescent layer to prevent chemical reactions between the intumescent material and electrode assembly.

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Early detection of thermal runaway events in sealed battery packs to quickly respond before propagation. The method involves monitoring pressure within the pack and analyzing pressure anomalies. Pressure peaks with anomalies are fitted with curves. If the trailing edge curves show exponential decay with a specific time constant range, it indicates thermal runaway. A response is triggered for that pack. Fitting and time constant checking distinguishes true runaway from false positives caused by vibration, altitude, etc.

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Early detection of thermal runaway events in battery packs to mitigate fire risks and damage. The system monitors the electrical isolation resistance of the battery pack. When the resistance falls below a threshold, indicating cell failure, it triggers a response. The response may include warning indicators, reducing load, increasing cooling, and fire containment. The response is based on factors like fall-off rate, time to recovery, and secondary effects like voltage drop, temperature rise, or humidity increase. This allows detecting thermal runaway precursors and taking action before gas escapes.

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Identifying the presence of an internal short in a battery pack using data collected during charging. The method involves monitoring various parameters like voltage, current, temperature, and charge efficiency during charging. Anomalous conditions like decreasing voltage, increasing current, higher self-discharge rate, or temperature spikes are evaluated against predetermined profiles indicative of internal shorts. If the comparing step identifies a relationship matching an internal short profile, it establishes an internal short state for the pack.

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Detecting and responding to potentially hazardous over-current due to internal short circuit in electric vehicle battery packs to prevent excessive heating and thermal runaway. The detection involves comparing patterns of series element voltages to identify if contiguous elements uniformly drop from the previous balanced condition, indicating an over-current short. The response involves summoning maximum cooling capacity to prevent heating until the short ceases or pack drains.

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A system for detecting thermal events in batteries like lithium-ion batteries to prevent runaway and fires. The system uses optical fibers placed near the battery surfaces to monitor light transmission. A light source shines through the fiber, and a detector measures the transmitted light. During a thermal event, the fiber attenuates or blocks light, indicating battery overheating. This allows early detection and response before full runaway. The system can use filters, splitters, and multiple fibers to isolate fiber health.

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Detecting and responding to high voltage electrolysis within an electric vehicle battery enclosure to limit possible excessive thermal conditions and prevent runaway thermal events. The system detects high voltage electrolysis, such as coolant bridging terminals and electrolysis, and responds by stopping the energy driving the electrolysis and lowering the coolant boiling point to prevent runaway thermal conditions. This mitigates risks from electrolysis-induced thermal runaway and hydrogen buildup in the battery pack.

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A vehicle thermal management system that allows precise control of heat rejection from the battery coolant to the refrigeration system. The system uses a bypass valve in the coolant loop that allows splitting the coolant flow between directly passing through the heat exchanger and bypassing it. This allows regulating the coolant flow through the heat exchanger based on coolant temperature, battery pack temperature, or other factors. The bypassing reduces heat transfer if the coolant is already cool enough, preventing excessive heat rejection to the refrigeration system. The system continuously monitors coolant temperature and adjusts the bypass valve to maintain optimal coolant temperatures.

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A multi-port, multi-mode valve with a single actuator that can selectively open or close fluid flow between pairs of ports without affecting flow between other port pairs. The valve has multiple inlets and outlets for a fluid like coolant. The valve uses a single actuated component, called a stemshell, to selectively open or close fluid flow between selected pairs of ports while not affecting flow between other pairs. This allows the valve to have multiple operational modes without needing multiple actuators or complex routing for different fluid paths like prior thermal systems.

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Heatsink design for liquid cooling of electronic components with internal fins that improve cooling performance. The heatsink has two cast parts, one with fins extending into an internal cavity and the other with fins that fit between the first part's fins. An inlet and outlet are on either part. The staggered fin arrangement allows efficient cooling by overlapping fin arrays. The internal cavity provides a contained path for liquid cooling. The cast fins can have drafts to aid manufacturing.

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Self-activating drain system for electric vehicle battery packs to automatically remove leaked coolant without human intervention. The system uses a passive drain device with a dissolvable element that reacts to the coolant and expands to open a valve and drain the leaked coolant. The device is installed in the battery pack enclosure wall and seals tightly when coolant is present. If coolant leaks, the expanding element opens the valve to drain the leaked coolant. This protects the battery internals from coming into contact with coolant if the cooling system fails.

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