Being able to charge your Phantom 4 batteries in the field has been discussed at length here before. The most common solution is an inverter between your car's cigarette socket and your Phantom's charger brick. My goal was to be able to charge without using a car, reduce bulk and in the event anyone was wondering if this could be a solution for them.

Being primarily a still photographer, I own two Paul C. Buff Vagabond Lithium(US $240) batteries I use to power my (non-continuous) lights. Since the batteries have AC plugs (and a USB as well!), I thought I would run a test to see how practical using one as a Phantom 4 field charging solution would be.

Summary
The Vagabond is a pure sine wave battery so no worries on damaging your Phantom 4 battery due to variable sine. It also has a built-in fan to dissipate heat. With a fully charged Vagabond battery, you should get 1 complete Phantom 4 battery charge from 20% to 100% with about 1/4 of power left on the Vagabond. Unless you already own one of these like I do, it's not an ideal solution for field charging but could be a solution for some depending on your needs, especially if a vehicle is not available.

The Vagabond battery is for you if
You already own one, of courseYou can't or you'd rather not use your vehicleYou want/require a lightweight (3.5lb), non-bulky solution
One full charge (plus another 20%) is enough for your purposes

The Vagabond is not for you if
You need 2 or more charges
Using your vehicle's cigarette socket is available or preferred
The price of the battery doesn't justify the amount of power

Testing
Using a two-week-old Phantom 4 battery, I drained it down to 20% via normal flying and plugged it into the Vagabond battery.

Charge time from 20% to 100%: 61 minutes
Vagabond remaining power: Less than 1/4
Second battery: I charged a second battery to completely drain the Vagabond. It took the 2nd battery from 20% to 40%.


Vagabond specs
        3.5 pounds total weight
Dimensions: 2.75” x 4.3” x 7.8”
14.8V 8.8AH LiNiMnCoO2 lithium battery (130 Watt-hours)
        120VAC inverter with two standard, 3-prong 120VAC outlets


Hopefully this information helps anyone. Thanks to all who contribute to these forums.

The published capacity of the battery inside the Vagabond unit is only a little bigger than the capacity of a single P3 or P4 battery, I don't see how that is going to help you.

i have a bike battery of 48vx20A which is supposed to offer 900+Wh/ loose 100Wh in the transfer and 3hr to recharge, still looks like i need 9 batteries to keep it going through. so before buying the camp power, i still need 2000$ for the 8 extra batteries. add 6-700$ for camp battery, you look at 3000$ extra.

I already have two of these I was not using as I have new lights with their own power source.  Thanks for the info, as now I can use them in the field to charge a couple of batteries!!

Same here.  I got two of them and they might come in handy as a remote field charger, when going from one shoot to another, or switching and waiting for a spare battery to charge.  I've been surprised how long they can run my studio flash units in the field too.  Even runs my large HP laptop for a hour too since its internal battery is shot.  I don't believe the Li-Po pack in the Vagabond-mini runs with the intelligent battery system as DJI uses so they have lasted me 'several years' and are still working (ahem!).  Plus, it has a USB charger as well.  The late Paul Buff really designed this thing well and there are copies of it out there for more.

Now if I could pair them to charge the I2 dual batteries somehow...

i wanna know where you got a red P4 battery?