CubCell LiOn Accu: USB Led and LoRa Delay


I have attached an LiOn accu to the cubecell board. The small led near the usb port beginns blinking, what does it mean?

My software works fine (it is based on, on every interrupt I see a message on the LoRa gateway. When i diconnect USB (board runs from LiOn) the message after interrupt is delayed for > 10 sec. Also i get retries on the gateway, which I do not understand. ADR is off, I send only unconfirmed messages.

About 1: This is the battery charge indicator.
About 2: Do you mean that interruption delays occur only when using Lion batteries?

About 2: Yes, only on battery