2017-11-02 - Proterra Abbreviated HVAC Spec Spheros

o
o
The pressure loss through the coolant side of the plate heat exchanger shall be ≤ 100kPa
at the nominal flowrate and 25°C coolant temperature
The coolant is expected to be 50/50 ethylene glycol/water
Heating
• The heating elements shall be operated directly off battery system voltage, which varies
between 560VDC and 740VDC
o It is preferred that the heating elements be PTC-based
• The HVAC unit shall have ≥ 16kW of total heating capacity at 650VDC (for conditioning cabin air
only)
Low Voltage
• The low voltage system (fans, valves, controller, etc.) shall operate at 24VDC
o The typical voltage range is 26.5VDC to 28VDC
o The minimum voltage the at which the system shall be expected to operate is 20VDC
• The low voltage system shall consume ≤ 3kW of power from the low voltage system
Controls
• The controls system shall support SAE J1939 protocol for control, feedback, and diagnostics
Electrical
• The isolation resistance between high voltage and ground shall be ≥ 10MΩ across all operating
conditions
• The isolation resistance between high voltage and low voltage shall be ≥ 10MΩ across all
operating conditions
• The total system x-capacitance across the high voltage input is expected to be ≤ 0.2mF
Other Targets
• Cost Target ≤US $20000.00
• Weight Target ≤700 lbs.
• Length ≤ 95 inches, Width ≤ 72 inches, Height ≤ 18 inches
Target segments: The requirement is applicable to all Proterra vehicle platforms (35ft, 40ft, 60ft). If the
solution is optimized as specified, it is possible that this unit would be the lead HVAC candidate for all
future vehicle programs.
Business Case: The design and development of the unit should be focused on optimizing cost and mass
while meeting Proterra’s performance requirements. Spheros to provide development cost, piece price,
and scope of development with milestone plan identified. Additionally, Spheros to describe standard
offered warranty, service support strategy and geographic presence in North America.