IanS wrote: ↑
Wed Jul 11, 2018 6:55 am
There are plenty of people powering the Pi in a mobile project from a LiPO power pack, but these are normally available in multiples of 3.6V, so you will need a 7.2V LiPO and then a voltage regulator to bring it down to 5V
Except new LiPos are 3.7v nominal and can be as high as 4.35v when fully charged. Two in series == 8.7v
Not mentioned is the fact you can run a Pi off a single Lithium Ion cell with a boost circuit.
This, in my opinion, is far safer.
By using one cell, you can recharge it without having to remove it from your project or fiddle with complex balancing electronics.
Additionally, if the boost module fails, your Pi will see 2.9-4.2v, which may be enough to run it until you can shut it down. Worst case scenario, your Pi crashes and potentially corrupts the SD card.
If, however, you use 7.4v and buck it down, and that buck fails, your Pi plus everything connected to it, will see 7.4v, frying it all instantly.