The battery was definitely not charging; I've determined the cause, not sure if it's a bug or 'feature'.  If the Hab's Reserve Power is less than 1% then it stops charging altogether and all the systems go offline, even if the systems themselves have 100 power units being supplied.   I tested this by running down the reserve power overnight, then during the day transferring it between the Hab and my suit to find the threshold value.  In the OP the cause of the low battery was a broken component, but repairing it didn't start generating power again because the Reserve Power was already below 1%.

Forgot to mention that the text "...Repairing slot for 0 minutes ..." is also stuck on screen; it doesn't go away, but the Time, Oxygen and Battery readings continue to change.