Hi. I have experienced a significant battery drain throughout the last months. I recently changed to a 2013 MacBook Air from my late 2010 Air and was disappointed because I thought the newer faster macbook took up more battery and therefore has less runtime. But I got curious when I saw the mds and mdworker processes come up in the activity monitor application with cpu load off 100% and higher. I therefore changed to the terminal application and used the lsof command to identify which files are currently in use and I found out that mds and mdworker are permanently using a file located in the LogMeIn Directory. LogMeIn is an application for remote access to you Mac. It is deactivated on my system currently but nevertheless recently updates a log file in this directory:
Not always but sometimes there are recent changes to the log file every few seconds and spotlight tries to add the changes to the index but has to do so every few seconds, what results in high cpu load for mds and mdworker process, what eats up your battery.
Simply add the following directories to the privacy area of the spotlight configuration in system settings panel:
/Library/Application Support/LogMeIn Plugin
You are done and you should not loose any battery any more on this issue.