TexasLeaf said:
I am planning a structured test this weekend to see how much blowing cold air down the Service Plug port, using the techniques I have outlined, helps cool the battery. I will post my results once I have completed the test.
I just finished the test to see if conditioned air blown through the Service Plug port could reduce battery temperature. I travel two identical trips on separate days under identical conditions, the first trip with the Service Plug port bolted closed the second trip with the Service Plug port open. Both days the outdoor air temperature was 82 degrees F for the 1st charge and 87 degrees F for the 2nd charge and with each trip I started out with a fully charged battery.
For the first leg of each trip I traveled 90 miles and CHAdeMO charged until the charged rate tapered to L2 (6.6 kW). For the second leg I returned the 90 miles and CHAdeMO charged again to L2 levels. I limited my speed to 60 mph and I monitored battery temperatures and charge rates using LeafSpy.
For the first trip with the Service Plug port bolted shut, I left the cabin AC temperature set-point at 60 degrees F on the travel legs with the AC in Fresh Air mode. I let the exhaust escape through the grilles in the trunk to simulate pushing air through the Service Plug port in the second trip. I didn’t want the energy consumption of the AC compressor on the travel legs to skew the results but I also did not run the AC during charging sessions.
For the first trip I started out with a battery temperature of 96.2 degrees F. The battery temperature had reached 102.2 degrees F by the time I started the 1st charging session and 117.6 degrees F at the end of the 1st charging session. The battery temperature was at 117.9 degrees F at the start of the 2nd charging session and 126.6 degrees F at the end of the 2nd charging session.
During the 1st charging session the battery reach a peak battery temperature of 118.1 degrees F at 15 kW. During the 2nd charging session the battery reach a peak battery temperature of 127.1 degrees F at 15 kW. Because I was using EVgo chargers that only allow 30 minute charge sessions and required multiple restarts to complete the charge, the battery temperature of 127.1 degrees F and 15 kW were both constant for quite some time.
I started the trip at 5:11 am and I finished the trip at 11:29 am. For the 1st travel leg I consumed 21.1 kWh, for the 1st charge session I added 19.9 kWh, for the 2nd travel leg I consumed 21.1 kWh, for the 2nd charge session I added 21.9 kWh. The peak charge rate for the 1st charge session was 29 kW and the peak charge rate for the 2nd charge session was 20 kW.
For the second trip with the Service Plug port open, I left the cabin AC temperature set-point at 60 degrees F with the AC in Fresh Air mode the whole time. I used the AC fan to push air through the Service Plug port. I covered the wind shield with a sun screen and I opened the hood to release condenser heat during charge sessions.
For the Second trip I started out with a battery temperature of 98.8 degrees F. The battery temperature had reached 102.7 degrees F by the time I started the 1st charging session and 115.1 degrees F at the end of the 1st charging session. The battery temperature was at 114.8 degrees F at the start of the 2nd charging session and 122.0 degrees F at the end of the 2nd charging session.
During the 1st charging session the battery reach a peak battery temperature of 115.6 degrees F at 20 kW. During the 1st charging session the battery reach a peak battery temperature of 122.8 degrees F at 17 kW. Again because I was using EVgo chargers that only allow 30 minute charging and required multiple restarts to complete the charge, battery temperature of 122.8 degrees F and 17 kW were both constant for quite some time.
I started the trip at 5:17 am and I finished the trip at 11:36 am. For the 1st travel leg I consumed 20.0 kW kWh, for the 1st charge session I added 18.7 kWh, for the 2nd travel leg I consumed 22.3 kWh, for the 2nd charge session I added 22.6 kWh. The peak charge rate for the 1st charge session was 29 kW and the peak charge rate for the 2nd charge session was 22 kW.
Even though the charge rates were generally higher for the second trip the total trip time was about the same for both trips. The additional power consumption on the second trip can be accounted for by the AC compressors running during charging sessions. But after two identical trips the battery was almost 5 degrees F hotter on the trip that did not use the Service Plug port with AC in Fresh Air mode to cool the battery.
I think it is pretty conclusive that the AC can be used to help control battery temperature on the 2018 Leaf. This trip only covered two charging sessions but on very long trips with multiple charging sessions, keeping battery temperature down may be far more important than consuming a little extra energy. My test did uncover some other pretty important discoveries but I’m going to start a new thread to discuss those.