How many of you store one of your batteries right in your Mavic?

I do for one, and I believe it's safe to do so if that's your concern?
Every Mavic (Pro at least) is delivered with batteri mounted.

Hi, Thanks for your inquiry. You can read our manuals on how you will take care of your drone's battery using our website.

https://dl.djicdn.com/downloads/ ... tery+Safety+Guides+(EN).pdf

There is always a battery stored in my mavic

I do and never had any problems. They come with a battery fitted, and some sit for many months in storage until sold.

Yes with all my craft no problems thus far.

What about letting the batteries rest in the charger?  The 4-battery one that comes in the Fly More kit, I mean.

Is that safe or will the batteries' 'auto-discharge to 65% after 4 days' feature be subverted by the charger (and I assume result in reduced battery longevity)?

Store all my Mavic Pro P batteries in Li-Po safe bags.  

always store the battery in the phantom , spark and mavic pro , no issues so far.