I need to charge my batteries out in the field. First I was think about a gasoline generator with a output of 1000w. Those are not that heavy and they offers more than enough with juice. The other solution would be a 12V lithium battery (LiFEPO4) battery with ~60Ah. No need to mess with gas and completely quite. Being a lithium battery I can use all the power without damaging the battery. I’m planning to connect a 200-300W inverter and then the battery charger for the Phantom. How many batteries (P3, 4.48Ah, 68Wh, 15.2V) would I be able to charge with a 12V 60Ah battery?