You know what it’s like, the sun is beating down, you’re out in your favourite bando and you’re running out of packs. You’re just warming up and you’ve already smashed that trick you’ve been practicing. You’ve got your footage, but you’re itching to keep flying. If only you had some way of charging a few packs up. You can with PiigBox. Designed around a chunky lithium-ion pack, they come with XT60 socket so you can run a lipo charger in the field.

How many packs though…
Well, after much research on the subject, I’ve settled on the following ‘scheme’ to determine that.

We calculate the mWh as a common factor for both the field charging pack, and the packs you’re using. I can hear you think “But you never fully charge a lipo, you take it from storage to full”. This is true, but the same goes for the field charging pack, you don’t want to fully discharge that. So I’ve found the aWh route to be the most appropriate:

For example:
Our 3S 12 cell 21700 packs use 5000mah cells
The mWh is calculated by multiplying mAh x V so 5000 (mAh) * 4.1 (Volts) * 12 (cells) = 246,000 mAh for the whole pack

We now calculate the mWh figure for your lipo batteries
For example:
A 6S 1300mah lipo would be – 1300 (mAh) * 21.6 (Volts) = 28,080mWh for the pack

So you can charge 8 * 6S – 1300mAh packs
or
You charge 10 * 4S – 1500mAh packs

I’ll do some testing to verify this but I’ll quote theoretical 6S 1300mah packs and 4S 1500mah packs in adverts.