FYI; light sleep current pulled out of the battery depend on the battery voltage:
<2.7V device wont wake up anymore
This dependacy is caused by the DC-DC conversion that converts the Lipo voltage first to 5Vdc. (SY7088 chip).
The 5Vdc gets also down converted to 3v3 (SY8089 chip) .
According to the datasheet, the ESP itself should only use 0.8mA in light sleep. So 2mA gets waisted.
What a pitty.
The above is not completely true. I'm using the M5GFX lib and when I execute the function display.sleep(); before going to deep sleep (esp_deep_sleep_start();) the sleep current drops to a 1.25mA. Still considerable...