Got yesterday those boost converters from China. From my endless scrap box I harvested Sparkfun single cell LiPo charger.

I modeled last night the Power Half 3D model (EDIT: https://github.com/skvark/TheOtherHa...epowerhalf.stl) and printed it today. Rest of the stuff was just pretty much soldering and gluing.

There's a power on/off switch at the bottom right side (there's inset so you can't turn it on or off accidentally) and USB terminal for charging.

Charging will light up bright led in the bottom left corner. When power is on there's less bright led at other side. Those leds are embedded to the Sparkfun board and to that boost converter board.

The power switch cuts the power between those two boards so the setup works in these modes:

1. Charge the phone only from the Power Half
2. Charge the Power Half only
3. Charge both simultaneously

CSD tool shows -780 - -790 mA charging current. The boost converter gets a bit warm but not too hot.

Costs for this setup were around 32-35 USD (23-25 EUR). Can be lowered by designing all-in-one board which has LiPo charger circuit + 1A 3,7 V -> 5 V boost converter. Unfortunately I don't have time to do it

Parts:

- Sparkfun single cell LiPo charger
- 1 A boost converter
- Copper tape
- 2000 mAh LiPo
- wire
- some SPDT power switch or something else

Pictures: http://relativity.fi/jolla_power/