The shield SD card reader for WeMos d1 mini will allow you to make small data loggers very easily. You can add a Shield Battery to operate the WeMos on a LiPo battery.
Arduino connection and code
The Shield microSD uses 4 pins of the ESP8266 (D5, D6, D7 and D8) to operate. A sample code is available from the Arduino IDE or from GitHub here.
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Micro SD Card Shield For WeMos D1 Mini TF WiFi ESP8266 Compatible SD Wireless Module For Arduino For WeMos D1 Mini
|Current Price||$0.54||12 August 2020|
|Highest Price||$0.54||18 April 2020|
|Lowest Price||$0.54||18 April 2020|
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|$0.54||18 April 2020|