Adding cooling ducts to my chargers was mostly successful. I am still able to make the chargers overheat (and shutdown) when charging in hot 95-100 °F outdoor temperatures at the maximum 30 A rate, but it takes them longer to do so. I can work around this by charging at a lower rate or delaying charging until the day is cooler.   I have my “80%” charging profile set to use the recommended 25A rate instead (and may even lower this depending upon the results of future temperature logging sessions).

However, on rare occasions I may need to charge as fast as possible for one to two hours at a charger away from home (to extend my range). I would typically not be making long trips in 100 °F temperatures, so I tested charging at the full 30A rate on an 80°F ambient day, which generated the following graph. (I have two chargers, so they each have their own watts and temperature line.)

The graph above shows a charging session that put 8.6 kWh into my battery pack over the course of almost 3 hours at 80 °F ambient temperatures. (If you are wondering why   one charger’s watts output drops out earlier than the other near the end of the charging session, you can read all about it here.)

My chargers typically shut down due to overheating when they reach 67 or 68 °C. From the yellow and blue lines, you can see that my chargers’ temperatures rose quickly from ambient to 60 °C ( 140 °F) in the first hour, and then the heat rejecting ability and heat generation equalized, so the chargers never reached above 63 °C. The manual states that the “working temperature” range for the chargers are -25 to 55 °C (-13 to 131 °F). The manual also has a note that “models whose output power greater than 2KW will ensure 2KW output at 60°C.” Looking at the graphs, I believe that I could charge indefinitely with the chargers hovering at 62/63 °C.

I would prefer that the chargers not go above 55°C in normal operation, which is why I’ve changed my 80% charging profile (that I use most of the time) to use a 25A max charging current limit.

But it is nice to know that I can charge at the full 30A rate for one to two hours in 80 °F temperatures if needed.   I may eventually mount the chargers on an aluminum heat plate in an effort to keep them under 55 °C while charging at full power for many hours, but that project will be much more involved.