Well, this is my take on it. When Ford designed the car, they did not expect people to buy this car and use it exclusively in electric mode. I think the intent was to use the EV mode in the city and use the ICE on the highway or on longer trips. The 240v charging thing was actually more of a downfall for some people, because it gave the opportunity to recharge the car very quickly and people starting using it to go in and out all day on electric power. Remember Gary drove almost exclusively on electric 100% EV all the time and went as far as going to the dealer to ask them to drain the "dealer" gas (free tank of gas he got with the new car) and put it in containers for him so he could burn that in his Ford Explorer, crazy right? I'm sure he got laughed out of the dealer or laughed on after he walked out. He lives in Florida and you don't see him on the forums any more...I'm sure his battery is worn out already and down on capacity with all the EV driving 100% of the time and his 500+ mpg average that he was so proud of.
Don't get me wrong I use EV when I can around town, but I also use the engine and travel quite the distances with the car. I'm pretty much netting somewhere around 68mpg lifetime with the car. Yesterday I drove to Boston, recharged there and drove back home. It was hot so what I did during that recharge was to program the car to run the AC while it was charging to keep the temps down inside. I got like 90% charge while I did my business and headed back home. I got stuck in traffic with the AC running and I'm sure the HVB got hot as it can't not with all the heat outside in the mid 90's so when I got home I just let it rest overnight and this morning I charged it from 0 to 20% and that's it, I'm letting it rest some more I don't need to use the car much today anyways. Later tonight I'll go to the store with the 20% and charge it there some after the sun has gone down.
Your best bet is to use the battery slowly and never draw more than 2 bars out of it. I turn off cruise control up hills and limit the battery draw to 2 bars and let the car slow down as necessary instead of having CC draw like 2.3 bars to keep up the speed up a steeper hill. Taking 1 hour to drain the battery for 30 miles is way better than doing it in 10 minutes at high speed.
Tom, after the summer is over it would be interesting to see where your HVB range ends up, I would expect some loss due to age and usage, but not as steep as last summer with the overheating and all the EV driving you were doing, I think you said you used to drive like 70 miles EV a day with recharging in between?