I discovered something today.
my train room/workshop is in an outbuilding. it has heat, but I only bring it up to temperature (58F) when I'm in there, otherwise I set the thermostat at 42F.
the other day I plugged my HC in at the end of the day, and I noticed the next morning it had not charged.
today I brought it into the house, plugged it in (to the Ring charger) and after a few seconds on the "charging page" it errored with "under temperature warning".
I unplugged it and let it warm up to room temp and now it's charging properly.
who knew??
Ken