When the 40's come out, will it be prudent to always charge them to max range, as this is still only 2/3 of battery capacity?
Unfortunatly we don't know where Tesla is hiding the reserve battery portion.
If Tesla chooses to hide the last 20 KWH then it would not be prudent to range charge as it would be the same as range charging the 60.
This is the most likly senerio as it would allow the 40's to have the best performance (higher SOC).
Give the two choices I would want the higher SOC. This would give you better performance and leave you battery some charge at 0 miles (to prevent bricking). Personally I would have the 40KW between ~30% and 95% of 60KW capacity. This would you allow you to regen if you changed to max range. I have found it a minor annoyance to loose regen for the first few miles after a max range charge.
As discussed in other threads the best option would most likely be using the middle 45kwh leaving a buffer at either end. Let us also hope that they will not wish to support the 40's going forward and will over time release the reserve and make them 60's. this would be a logical path to reduce cost of maintaining a separate software branch for such a small user base.
I wonder if it's possible to lose regen by full-charging a 40. Anybody tried?
Nobody has a 40 yet.
In the end, no one will know until a 40 is delivered. My suggestion is to range charge it when you get it. If regen is initially limited after a range charge then Tesla has locked away the bottom 20 KWH and range charging would be the same as in a 60.
Interesting question, and one I've thought about daily since they made the announcement that the 40 would be eliminated. My feeling is that they will NOT release the reserve (as murraypetera suggested), since that would leave the 60 owners feeling angry that they paid an extra $10,000 for nothing. I also have a feeling that TM won't tell the 40 owners what part of the battery is locked and unusable.
My 2 cents is worth exactly that.
If the bottom 40 is locked away picture this:
A dark and stormy night in North Dakota in December. A phone calls begins.
Tesla Rep (TR): "Thank you for calling Tesla. How may I help you?"
40 Driver (40): "Well, I'm stuck on the side of the road. I ran out of power. It's -35F, there's a blizzard out, and the place is swarming with zombies."
40: "Yes. They're trying to eat my face. I know there's an extra 40kWa of power in my car. If you could just unlock it for me."
TR: "Ah yes. No problem. If you can just give me your credit card number, I'll run it for the $11,000 upgrade":
40: "I DON'T HAVE $11,000 AVAILABLE CREDIT. If I did I would have bought a 60 to start with. Is there anything else you can do?"
TR: "Well, there is this little Easter egg in the car. The ZDM."
40: "The ZDM???"
TR: "Yes. The Zombie Defense Mechanism. Elon's very proud of it. He tries to thing of everything."
40: "OK OK I'll take it. How much is it?"
TR: "It's only $4,500. I can take your credit card whenever you're ready". (Gets info). "Sir, I'm sorry but your credit card was rejected. It seems you went over the limit buying a Central Console Insert"
40: "So what can I do??"
TR: "I'm patching you through to John Broder at the New York Times. Perhaps he can help you. If not he'll have a great story to write. Have a nice evening. Goodbye"
There isn't an extra anything. You do not have access to the extra 20kwh of POTENTIAL energy in the battery and wouldn't help you during the zombies because you would then need to CHARGE the battery still. Or at least that is my impression.