Disconnect battery negative, wait...(1 minute, 10 minutes, 30 minutes...depends who you ask) solves a lot of gremlins with LR's. Same key fob problem happened when I let an auto shop tech perform a "free scan" and reset codes...fortunately the "disconnect negative terminal and wait" trick did the job, and I learned my lesson about "free scans"!
Regarding battery going dead, as others have noted turn the interior lights off, they pull a surprising amount of current. Also, assuming keyless ignition, stash the key away from the vehicle. Every time the computer 'sniffs' the key it wakes up the system, ready to start.
There is one point on the vehicle where the key can be easily stashed out of range of the sensors (PM if you need to know where)
Regarding battery going dead, as others have noted turn the interior lights off, they pull a surprising amount of current. Also, assuming keyless ignition, stash the key away from the vehicle. Every time the computer 'sniffs' the key it wakes up the system, ready to start.
There is one point on the vehicle where the key can be easily stashed out of range of the sensors (PM if you need to know where)