If you're like me, you've been searching the web looking for answers to this question.
Apparently there is a new firmware update available for the Phantom 2 "Smart" battery which will allow the battery to automatically begin a discharging process after 10 days without use. (FYI, the battery takes roughly 2 days to automatically discharge this way, and will discharge itself to about 50% power. Also any time the battery button is pressed, the 10 day countdown refreshes again.).
However, that being said, some people have said that DJI recalled this firmware update, so personally speaking I don't trust this as a viable solution.
So, what to do? As with all things DJI, since their customer service is so brutal all you can really do is scour the internet and be your own source of tech support. I discovered this helpful post in one of the forums. See answer below:
That being said, I've read on some forums that discharging the battery below 50% is not necessary and could cause damage to the battery. Also, given that the new firmware update automatically discharges a battery to ~50%, we can only assume that ~50% must be the proper discharge level.
As per the DJI Wiki Correct Battery Usage Notes:
Another thing you might be wondering is what do the Phantom 2 Battery LED indicators mean? See table below: