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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

Energy storage pack design with improved thermal management for battery modules. The pack uses scalloped cooling tubes that connect between cells instead of having the cells directly attach to the module housing. This allows curing the adhesive between cells and tubes using radiation. Areas shielded from radiation are cured using a secondary mechanism. The scalloped tubes also have curved or slanted internal ribs for easier manufacturing and better thermal performance with bends. The flexible module design allows using different cell types, orientations, and placeholders.

Containing and separating debris and gases during thermal runaway events in electrochemical cells like batteries to prevent ignition. The system uses a vortex separator inside the battery enclosure with an inlet from the battery chimney and outlets to the outside and a catch basin. During a thermal runaway, particles ejected by the cell are confined in the catch basin while the gases escape through the vortex separator. This prevents sparks from contacting the gases and potentially igniting.

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.

Battery service unit for charging and discharging high voltage battery packs without needing the pack installed in a vehicle. The unit can maintain and manage battery packs outside of a vehicle to set desired charge levels. It provides features like discharger, power supply, controller, and simulation circuits to duplicate vehicle characteristics for operating environments. The unit connects to the pack's primary port and discharges/charges when needed, bypassing the pack's BMS if faulty. It can also test packs to determine if they're functioning properly. This allows servicing packs outside a vehicle without needing a functioning vehicle.

A manufacturing method for lithium-ion cells that improves efficiency and accuracy by using a liquid-based thermal system to condition the cells during various stages of assembly and testing. The method involves storing cells in contact with a liquid thermal system after assembly, circulating liquid at a first temperature, then cooling to a second lower temperature before testing. This allows even heating and cooling for more accurate capacity checks. The cells are discarded or kept based on open circuit voltage tests at different temperatures.

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.

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.

Thermally conductive dielectric pad for attaching electronic components to heatsinks that uses adhesive on both sides of a ceramic tile instead of thermal grease. The ceramic tile with adhesive on both sides is sandwiched between the component and the heatsink. The adhesive provides thermal transfer and electrical insulation. The adhesive is pre-applied to the ceramic tile or introduced after assembly. This eliminates issues like grease pumping, drying, and contamination compared to thermal grease.

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.