Circuit diagram

Connection assignment

GY-521

D4 -> SCL of the GY-521
D3 -> SDA of the GY-521
5V -> VCC
GND -> GND
remaining ports unoccupied
Remove the resistor of the GY LED! (Retirement)

Resistors

BAT43 or better schottky diode (cathode to D0) or 330 ohms resistor between D0 and RST
230k ohms of A0 -> 5V
4k7 ohms of D6 -> 5V

DS18B20

DQ goes to D6 VCC and 5V
GND -> GND

Wemos

Remove the input diode (short circuit via Lipomodul!)
Switch / Reed between + 5V and Lipomodul + OUT
GND -> GND

Lipo Lademodul

Battery to B + and B-
GND -> GND
+ OUT switch to + 5V Wemos D1 mini
+ IN to USB + 5V of the Wemos D1 mini (optional)