This is why I love EV+, and really miss it these days, as it hasn't found my place of business yet after the last PCM update.
EV+ is a way to get more EV range out of the car at a time when it's very safe to do so - just before a rest. As Plus 3 notes above, you can't discharge the HVB fully, so there's no danger there.
A little research reveals that EV+ may be a very smart thing to use! This comes from Battery University, reporting on research performed at Ohio State, in conjunction with Oak Ridge National Labs and NIST.
You kill Li-ion batteries by storing them fully charged, and at high temperatures.
Optimum storage conditions are 40% charged.
Sound like EV+ is one easy way to consistently leave the HVB at a favorable charge level to minimize charge capacity loss during storage. That kind of trumps all the other arguements, don't you think?
I wouldent take what you read from one source as fact. I have heard so many "facts" about how you should store lithium ion batteries that I dont think anyone actually knows. I have heard reputable sources, including battery manufacturers, say to store them at 90% charged, others say 50%, and everything in in between. The only common ground I have found is no one recommends completely discharging them.