the How Intelligent Batteries Work link discusses storage of your batteries at 50-65%.

what duration is "not used for a long time"?  a week, a month, 6 months?

when i complete a flying session (going through 3 batteries), each battery is around 8-14% charge level.   if i don't plan to fly for a few days, a week, sometimes more, i leave them that way until i know i will fly again.  i put them in the docking station and charge them up the night before.

is there any problem leaving them in the nearly discharged state (~10%) for 1-2wks or should i bump up the charge to the 50-60% level before letting them sit idle for "awhile"?

Yet another battery video:

Don't leave you battery discharged at 8%-14% for any extended period of time -> it's not good for the life of the battery. After they cool down, it's best to charge them back to the 50%-60% level.

I have an extra battery that I've only ran down to under 50% once or twice.  Never once under 30%.  

It's only 3 months old and has been stored (numerous times) for a few weeks with a charge of 70% to 90%. Probably  charged it (more like topped it off) about 10-15 times since I bought it.

Should I do a deep discharge of it just to assure the readings are correct?  

0DRK3RT Posted at 2016-1-1 17:37
I have an extra battery that I've only ran down to under 50% once or twice.  Never once under 30%.   ...

You should not need to discharge the batteries for storage. There is a setting in DJI GO to set the time before the batteries "auto discharge" to storage levels. I suggest that if you do run them below 50%, then best to recharge them to full (after they cool) and let the battery discharge as it is programmed to after (normally 7 to 10 days). My batteries have discharged before, it's great to have a feature like that, as I had to manually discharge over 20 Lipos for my other aircraft (for the winter when I will not be flying). Hope that helps

The simple answer to your question is no, leaving batteries in a discharged state will not harm them. Fully charging them and leaving them may cause swelling, this is why the intelligent battery function discharges them after a certain time. What you are currently doing is fine.

Nathan B Posted at 2016-1-1 21:02
You should not need to discharge the batteries for storage. There is a setting in DJI GO to set th ...

Thanks Nathan. Funny thing is, i noticed my batteries were not auto discharging as programmed, but didn't really follow up as to why until very recently. (New dad here, life is a bit hectic)..

Come to find out, any time you push the power button to check the levels, it resets the auto discharge timer.  Mine are programmed for 10 days, and I will use periodically check the battery level within 10-13 days. Found it odd why it still showed 3/4 LEDs.

So essentially, I've been storing this poor battery at levels WAY above the recommended 50% level since I bought it.

Given all the recent reports of batteries going from 90% to critical and falling out of the sky, as well as cold weather flying issues, I just want to make sure the microchip reading the battery levels is accurate.