One of the great weaknesses of smartphones is that battery performance is deteriorating, primarily because more apps are including geolocation facilities, constantly feeding data back to the app providers.
There are two simple ways to extend battery life. The first is to be more circumspect about which apps you allow to access your data. But unless you let an app use such facilities you may never know what it can do.
Alternatively, you can carry an additional battery supply. A couple of weeks ago I bought an Anker Astro mini. Only slightly larger than a cigarette lighter it is a great way to regularly top up your battery so you can be sure of having power all day.