My battery is at about 40% after not using it at all today. This is strange (for me); my phone usually will usually be at 80% after not using it all day. When I looked at what used the most battery it was "Cell standby" [34%] and "Phone idle" [27%]. What are these, and why did they take up so much battery? They seem like processes that shouldn't take much battery at all (standby and idle). Thanks.