@scottsweb I was able to get 2.5 hours on a 3.7V 600mAh battery plugged straight into VIN/GND (no other circuitry in between). I was able to get 11 hours when putting the Core (with u.Fl antenna) into deep sleep and waking up once per minute to publish data to a web service using TCPClient (instead of Spark.publish()). I got 12 hours out of a Core with the chip antenna running the exact same code. I need to recharge my lipos and do some more testing with less frequent intervals to see how far I can get that battery to last. I’m hoping to get to 24+ hours of uptime on a single charge.