This seems like a strange design decision but here’s what support told me:
Thanks for reaching out for assistance. Your solar power accessory looks like it has started providing power to the SKY unit again - after examining the battery voltage data it appears the battery was only depleted. This was likely due to the cold, as freezing temperatures will artificially lower the voltage and prohibit charging cycles to prevent damage to the battery. Re-charging a LiFePO4 battery in freezing temperatures will cause irreversible damage to the battery. To protect the life of the battery in the solar power accessory, charging will not occur when air temperatures are at or below 0°C (32°F).
If this happens again:
- To get your SKY back up and running ASAP we recommend using lithium batteries (best for use in low power outdoor electronics in freezing temps). As long as outdoor temps are at or below freezing, you may need to continue using 8xAA lithium batteries. Here’s a help page with more info:
https://help.weatherflow.com/hc/en-us/articles/360001913374-Batteries-Solar-Power
- You can troubleshoot your solar power accessory (SPA) to make sure it’s okay otherwise. First, you’ll need to detach the SPA from in between the SKY and its mount. Take the SPA inside and leave it by a sunny window for at least a day or two. When convenient, (even if that means spring) re-attach the SPA to the SKY and then check the battery voltage in the app.
Remember to take the AA batteries out of the SKY when using the SPA. Also, align the arrows on the SPA and base of SKY and then twist to lock.
To check the battery voltage, go to Settings > Stations > (choose a station) > Status > scroll down to SKY’s Battery > if it’s above 2.1 volts there is enough charge to power the SKY.
To enable a battery indicator display, go to Settings > Stations > (choose a station) > Advanced > Enable Battery Card.
If outdoor temperatures are on the cusp of freezing, you will be able to continue using the solar power accessory; it will still provide power but it won’t be able to re-charge the battery in sub-freezing temperatures. Low sun angle and minimal daylight hours are not an issue to keep the battery charged.