So far I have used a rechargeable 3.7 V LiPo battery with 1200 mAh. Unfortunately, the RasPi turns off after a few seconds when the Python script is started and all LEDs are blinking. I guess the LEDs draw too much current, or I have a bug in the circuit, or it may be due to the missing level shifter for the NeoPixels.

Anyway, I ordered new prismatic LiPo batteries with more mAh for testing. Every millimeter in thickness counts, even though I had already increased the height of the main shell. I'll go with the 2000 mAh LiPo.

These are the dimensions of the LiPos I tested (own measurements, vary a bit to the product numbers):

• 1200 mAh: 5 mm thick, 61 mm length, 36 mm width (LP503562)
• 2000 mAh: 6 mm thick, 66 mm length, 40 mm width (LP654065)
• 2500 mAh: 7 mm thick, 61 mm length, 51 mm width (LP785060)

I had previously tried to leave space in the upper area for the lid with the recessed pocket for the handheld scanner (Medical Mark X). But that's not going to work. I need the space for the wiring and it will be a very tight fit with the battery included. I will therefore use a flat rear lid, so it will be a Mark IX Science.

I had originally planned to attach the Raspberry Pi and PowerBoost module to the lid. I dismissed this idea and decided to install the RaspberryPi with the PowerBoost module and LiPoPi circuit first and put the LiPo battery on top last. This makes it easier to remove the lid and access the battery and RasPi.

When the battery is inserted in vertically (portrait format), the PowerBoost module can be placed next to it and the height of the JST socket is no longer a problem. There is also enough space below the PowerBoost module to insert the LiPoPi circuit there. And at the top left I can add the power switches.