Has anyone tried adding a scoop-like part to the air inlet on the left rear window to try and force more air into the battery pack for cooling? My FEH (2008) is quite old with a lot of miles and it's slowly turning into a frankenstein car with stuff bolted to it everywhere and wires running along the outside of the pillars so I don't mind aesthetics anymore lol. I wonder if increasing ambient airflow can increase the amount of charge/discharge the HV battery can take before the BMS limits it due to heat.

 

I think the battery cooling fans should draw in plenty of air for battery cooling providing the battery air filter is clean. An additional scoop would only be functional at highway speeds and wouldn't help in stop and go city driving where battery overheating is more likely. It is possible to monitor the temperature at the rear evaporator using using the Forscan software. I would put my energy into keeping filter clean and making sure AC is working properly.

 

You should leave it 100% stock and make sure the rear AC and fans work properly. Don't mess with the design. Don't pass Go and Collect $200. If you need to get inside the exterior vent assembly to make sure everything works, it's not that difficult. Everything "lives" in the rear cargo compartment driver's side trim panel which is not difficult to remove. If you think the airflow is obstructed somehow, that's probably *debris* doing it. Adding a scoop will only bring in more debris. The system itself was engineered very well on the 2008.

The AC on your car has a second evaporator that should supply "ice cold air" to the battery when it is hot. The only reason I can think of doing this is that yours isn't working properly. The car's A/C system and the battery fans should supply PLENTY of cold air when needed unless the system is malfunctioning.