Traction battery specs and usage

Greetings,

I'm interested in knowing exactly how much (or rather, how little) of the traction battery's useful range is being used. Does anyone have a direct source for that info? I've read here that default SoC is 60%, top of the battery indicator is 80%, and don't know about the bottom.

I'm pondering expanding the range through the software. Toyota states that they have not had to replace a single Prius traction battery because of an end of life issue. Perhaps we could use a little more of the battery's charge/energy storage range without comprimising the useful lifespan, hopefully at reducing it to equal the lifespan of the car. And of course, this could also extend the range for EV mode, and possibly allow useful charging for really short trips (perhaps as much as 2 miles, instead of the 1 mile we now have, if one would install a charger.)

Regards,