Your github repo isn’t public so I’m not able to view it. I’d have to see the sketch to understand what’s going on with the logger code, but I’m guessing there’s a variety of factors involved in the failure. One is that it looks like your station uses way too much power overnight, so either it’s not sleeping properly or you’ve got some LEDs on or something else that is consuming power because a station reporting every 15 minutes shouldn’t drop that quickly overnight unless there’s a big load like a sensor wiper motor or other power-hungry device. From the MMW page, it looks like it’s also got an old Digi LTE board on it? That also uses more power than the more efficient modules we use now, so a lot of your draw might be from that too. And I’m guessing it’s probably a Mayfly v0.5b board too? Newer versions use power directly from the solar panel during the day to allow for fully charging the battery on the side, rather than always drawing from the battery and trying to charge it at the same time. It’s been awhile since we’ve had any Digi boards on our stations, but the battery chart looked similar to yours. I’d recommend putting a new, fully-charged battery on the station and, but also look into why the power drops so quickly when there’s no sun.