Best way to do Long Term Storage?

Should be able to turn all the lights on and run the AC or Heater while in EV mode for ... some greater amount of time than driving it around would take to drop to the EV-HV threshold.

I think the idea is just to get close to that HV to EV charge threshold by whatever means you need to. Charge it up a bit if it's too low, to give it a good "glide path" in time before capacity reduction starts to creep-up. Drain the charge if it's too high, to reduce that detrimental parasitic self-discharge current, which will also keep capacity reduction to a minimum.

 

The EV range showing on the dash with the corresponding EV SOC 100%-0% is, in reality, 84%-14% of the traction battery. When Prime runs out of EV range, the real SOC is ~14% and it switches to HV mode automatically. Then on HV mode, the car keeps the real SOC between 8%-16%. 8% is what I have read on one report, but I've never seen my PRIME go down below 11% SOC. Here is a graph of corresponding SOC level from Hybrid Assistance (HA in x-axis) vs what is shown on MID (y-axis).

If you want to keep your battery real SOC in 30-40%, then keep the MID displayed SOC at 35-45%.

 

Perhaps Toyota's engineers have evidence that when at lower charge levels their battery self-discharge is lower than Battery University's working numbers. That would be one explanation for their recommendation being lower than Battery University's.

 

Another explanation is the usual disconnect between development and support. Creating documentation is difficult in the first place. Updating is even more difficult, especially if there are a variety of models. You have to verify information on a regular basis, which becomes resource intensive for everyone involved. Most of the time, what ends up getting written & maintained is generalized as a result. In fact, that's why there is that standard "may differ" disclaimer in most manuals & instructions. And that's if you're lucky. Working in the world of IT developing software for decades now, I can tell you of countless times documentation was either inaccurate or never correct.

Of course, all that assumes an audience that isn't dealing with misconceptions. We also have people intentionally working to undermine the information being shared. That reality along with having many differing approaches all sharing similar terminology, despite the technology sometimes being fundamentally different, adds a complexity most automakers don't want to deal with. This is why advertising has been weak and support even weaker. The hope is the audience itself will help bring about the necessary education... hence, us.

In other words, step back from the detail, consider purpose. What message is Toyota attempting to convey? I could be as simple as just wanting to provide some background, giving you something to work upon for finding what you specifically need to find out.

Looking at it from another completely different perspective, what obligation does the automaker actually have to provide information?

Sorry, but that's the can of worms you opened by asking an innocent question.