I´ve been doing some research on the auto-discharge system of the P3 battery and didn´t find much. I did so in hopes to better understand its function and find out how the system can put the necessary load on the battery to get it down to the desired level. I mean, you need a resistance of some sort (a light, a motor, etc.) to turn the charge into heat, movement, whatever. But the smart pack only has a few LEDs I guess. I once kept an eye on a discharging battery and noticed it didn´t even get hot, and it was supposed to... to the point I wasn´t sure it was discharged, but the LEDs confirmed it was.
That´s to say I trust the P3 battery smart management system, to fly and keep charge and even balance within acceptable parameters - but not entirely this "auto discharge" part which I don´t know entirely how it works. I dunno the long-term effects of this discharge into the balance of cells which is quite a delicate matter when it comes to multi cell LiPos.
So I leave my batteries charged even for a week (but never above that), if I had a flight planned that didn´t happen for some reason. And I prefer to take off with, say, 97% or something, than keep discharging/charging and as in doing so "eat" through the LiPo precious cycles. The whole storage deal is about improving the battery life, more than performance - i.e. to get more cycles from the battery. So I see not much of a point for most pilots. Maybe newbies or the general public was their target, who knows. For me, if a LiPo starts acting weird I try to recondition it (balance). If it works then fine, it gets to fly. Otherwise I just get a new battery. Better spend $120 and be safe than "save" and maybe sorry.
What really harms LiPos is overcharge and deep discharge, and also unbalancing. Also heat can harm them. More than storing them full, at least in my experience. Either way, the expected lifespan of these batteries is quite large, unless they take hits, get dropped, get too warm or too cold or get discharged beyond their minimum (about 3.5 volts) frequently. I don´t worry too much with overcharging because the smart controller does control top charging. Well, at least it´s supposed to
They also seem pretty good at keeping balance between cells, which can be a problem if gone bad.
Please don´t take it that I´m recomending anyone to do differently than advised by DJI. By all means, follow the manual if you wish or doesn´t want to take chances. It´s just that I´ve been dealing with LiPo (and before that, other types) for some time and I prefer to perform "smart" management of batteries with a good, computerized charger. The kind that not only can cycle reliably through charge-discharge levels for flying, conditioning and/or restoring (balancing cells), but give accurate status info. For the day-to-day I use a voltimeter on the top of the GO app info provided to see how the cells are doing, and that´s more than enough.
