The message requesting battery status is placed in a send/transmit queue. When the device wakes up (it “announces” that it is awake by sending a message to the controller), the binding sends the messages that are in the queue. Note that the queue is memory-based, so those queued messages won’t survive an OH restart.
With the binding in debug mode, you should be able to see the battery request being placed in the queue. And, some time later, you also should to see the wakeup notification being received by the binding, along with the queued messages being sent.