AA Battery Powered 5V USB Supply (MT3608 Boost Converter Case)

A compact and support-free 3D-printable battery box for 3× AA cells, a MT3608 boost converter, a standard rocker switch, and a USB output. It reliably provides 5V at 500 mA – perfect for powering small USB devices, especially those that don’t work well with regular power banks. Once setup the MT3608 should always deliver the same voltage even when you switch between AA batteries and rechargeable AA NiMH cells.

Why?
Many USB-powered devices draw very little current and cause regular power banks to shut down or not turn on in the first place. This DIY solution stays on, making it ideal for microcontrollers, Raspberry Pi Zero, and other low-draw electronics.

Features:
Designed for 3x AA cells (1.2–1.5 V each)
MT3608 boost converter slot
Rocker switch to fully disconnect power
USB output (solder directly to Vout pins)
Delivers stable 5V @ up to 500 mA
Works with AA batteries or rechargeable AA NiMH cells
Uses metal springs as battery contacts
Support-free print, no rafts or brim required

Assembly Instructions:
Print the case orientation flat, opening side up
No supports or brims needed
Material: PLA, PETG, or ABS

Components:
3 AA cells (in series)
Metal springs for battery terminals
MT3608 Boost Converter
Standard rocker switch (19×13 mm opening)
Solid wire/cable No glue needed if wiring is good.

Wiring:
Connect the metal springs to form series connections between cells (soldered)
Connect the positive end of the battery series to VIN+ of the MT3608
Connect the negative end through the rocker switch to VIN−
Adjust the MT3608 to output 5.0 V or 5.2 V using the potentiometer.

Solder USB output:
VOUT+ → USB Vcc
VOUT− → USB GND