While it's been documented why this is, but you didn't ask that, I'll stick to what I do.
A few things actually.
1. I put my phone into airplane mode a lot.
2. I follow the ABC rule (Always Be Charging) since I don't want to buy a new battery in year 2. This rule, batteries is well discussed.
3. If I do want cell service I'll disable bluetooth, WiFi, GPS and data use.
In my day to day life I travel around my town and maybe to nearby towns. At the end of the day my cell phone will be down to the 70-75% power range (I don't use it all that much). But every time I travel to a friend's house which is in the next county and in a narrow valley, and not all that far from San Francisco, when I go home that evening my phone gives an alarm that it is about out of power. What's the deal? Anything I can do?