I'd recently read Roving Mars by Steven Squyres and in it he talks about how one of the heaters in the arm of the Opportunity Rover was drawing a half-amp over night and it was severely costly to it's power usage.
Opportunity’s stuck-on heater is still sucking 170 watt-hours out of the rover every sol, and we’re starting to feel it badly.
Roving Mars: Spirit, Opportunity, and the Exploration of the Red Planet.
They decided to implement Deep Sleep to save power overnight when the Heater is usually stuck on. The downfalls of Deep Sleep, however, is that the Rover wouldn't be able to carry out long Mössbauer and APXS measurements because the battery was off and was likely to kill Mini-TES.
Although for the rest of the book Mini-TES seemed to survive, and as far as I can tell it continues to survive (even though winter temperatures were dropping dangerously close to it's operational limits).
Did they simply continue to use Deep Sleep and put Mini-TES at risk or have they found a new solution to saving power while keeping Mini-TES safe?