No problem .....
Only comment I can pass now is that some people recc'd the multi battery charger bases that use the DJI power brick as supply. Why I will never know. They are a total con and grossly overpriced. They sequential charge - that means they charge one battery - THEN the next and so on. Useless in my view.
The only worthwhile multi battery unit is one that simultaneously charges, but they cannot get enough power from a DJI brick. THEN you get an absolute benefit of not waiting to charge next battery. In fact a single DJI charger is better IMHO ... you can plug in next battery while flying with first and still wait the same time as the daft sequential unit !
There are various adaptors that can charge multiple batterys from a single LiPo charger ... or you easily make one yourself. There are various LiPo chargers that have multiple outlets that are individually programmable outputs.
DJI has a simple power brick system to charge, the P3A / P3P charger is about as high an Ampage you'd want to go to be safe and not push limits of the battery pack. The P3S charger is lower wattage and slow charging ... but still reasonable safe rate.
I don't know much about the P4 setup as I have no P4 at hand. I would assume similar ..
For the average DJI only flyer or anyone who just wants convenience - the car charger via Ciggy Socket of eBay for a few $ is well worth it and enough. My car charger cost about $5 and works a treat for my P3 batterys. I can even charge a battery while driving to flight site. (close by - so I can throw out of window if needed !!)
Nigel