I'll move this here from the computing thread:
TIL that Opportunity was having to go into deep sleep mode every night because one of the heaters had failed-on during the landing, and would otherwise drain the battery. (This may have contributed to its demise, if the realtime clock got reset due to low power.)
Apparently the Lithium-ion battery was at 85% of initial capacity at the end of the mission. Which (as with the current generation of electric cars) just goes to show how well they can perform when managed properly.
