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2024 Prius Prime PHEV High-Voltage Battery Deep Dive
0:00 Introduction: The video explores the 13.59 kWh high-voltage battery of the 2024 Toyota Prius Prime PHEV, which is refrigerated, unlike earlier air-cooled Prius batteries.
0:36 Battery Specifications: The battery has a nominal voltage of 266.4V, a capacity of 51 amp-hours, and contains 72 prismatic cells.
2:06 Heat Shields: Thin, delicate heat shields/insulators (unnamed in Toyota's service information) are located at the bottom of the battery housing and between cell stacks to isolate the stacks.
2:56 Battery Heater: A low-voltage (12V) electric heater, similar to the one in the 2017-2022 Prius Prime, is present. Its primary function is likely to prevent electrolyte freezing, not for general battery warming.
5:42 Battery Cooler Sheet: An aluminum "cooler sheet" with channels for refrigerant flow is used for cooling. Refrigerant enters one side, snakes through three channels, and exits the other.
7:27 Three Cell Stacks: The battery comprises three stacks of 24 cells each, connected in series.
11:02 Limited Cooling Contact: Each cell has a small contact area (approximately 1 inch square) with the cooler sheet for heat transfer, using thermal interface material.
13:01 Cell Series Connections: Cells within each stack are connected in series using bus bars, forming a serpentine pattern.
14:07 Cell Voltage Monitoring: Each cell's voltage is individually monitored by a dedicated computer.
14:55 Temperature Sensors: Each cell stack contains five temperature sensors.
16:48 Wire Harness: Specific wire harnesses and brackets must be installed before the third cell stack, due to bolt access limitations.
23:08 Manual Service Disconnect: The manual service disconnect lever (service plug grip) with a large fuse is located under the rear seat cushion.
23:30 Refrigerant Lines and Control: The refrigerant system includes an inlet line with a "magnet valve" (precision stepper motor), temperature sensors at both inlet and outlet, and a pressure sensor.
26:14 Unavailable Service Tools: Special service tools for this battery are currently unavailable in the USA, making leak checking difficult.
29:56 Battery Junction Block: Contains the positive and negative contactors, but no pre-charge contactor.
30:19 Pre-Charge Method Change: The Prius Prime (and likely other Toyotas) now use the DC-DC converter bidirectionally for pre-charging, eliminating the need for a dedicated pre-charge contactor.
32:42 Battery ECU: Includes both the main battery ECU and the cell voltage sensing computer.
33:11 Battery Heater Relay: Controls the low-voltage battery heater.
39:20 Refrigerant Service: Discharging and recharging the refrigerant requires a special scan tool procedure to open solenoids and stepper motors, preventing trapped refrigerant.
40:15 Battery Vents: Two vents are present: a Gortex vent for pressure equalization and a spring-loaded door for rapid gas release in case of thermal runaway.