Dave:

Various things will affect the endurance of the battery in a battery powered device such as a phone... some of these we can control, some we can 'fix', and others we can't do anything about.

Things we can control:
Turn off some or all of the wireless transmitting functions. If you don't have a headset or GPS navigator connected to the phone, turn off the Bluetooth function (if your phone has this feature - chances are it probably does).

If you are not actually using Wi-Fi on the phone (meaning, if you are not actually connected to a Wi-Fi hotspot right at this moment, for example, when you are riding down the road) turn off the Wi-Fi connectivity.

If you don't need continuous phone and email connectivity (again, a great example is when you are actually riding the motorcycle), turn off all the transmitters in the phone. This is super-easy to do, you just put the phone into 'Airplane' mode. That will greatly increase the battery life - by greatly, I mean it will at least triple the battery life if not more.

I do a lot of long (one month or more) motorcycle rides. I put my phone in 'Airplane' mode (all transmitting and receiving functions off) during the day when I am riding. I might occasionally turn it on at lunch for a few moments (to see if any emails, voicemails, or SMS messages have arrived), and of course, if I want to use the phone I turn it on, but for the most part, I leave the darn phone off (in Airplane mode) during the day. It's not like I have to worry about some urgent message from the office arriving when I am on a moto holiday.

Things we can 'fix': Earlier this summer, my two year old iPhone 4S battery life had degraded considerably. The phone would last about 12 to 14 hours (with everything on), and that was it. I took it to the Apple store, planning to get the battery replaced, and the techs there suggested that I back it up, do a 'factory reset' (basically, this means wiping it clean), then re-load it from my backup. I was skeptical, but I did this, and I was pleasantly surprised to find that the battery life doubled... I was back to charging the thing every second day, instead of every day.

I presume that just like computers, smartphones get clogged up with crap and bits and pieces of software (programs) that run in the background even though we are not using the program. I can only presume that a 'fresh start' cleans out this crap.

If appropriate, consider buying a new battery (if you don't want to buy a new phone). But, before you do that, try the above clean-out and reset procedure.

Things we can't do anything about: Phones use up a heck of a lot of power searching for cell networks to connect to. You can see evidence of this if you leave your cell phone turned on during an aircraft trip, or when you are far out in the back-country where cell reception is spotty. In either of those cases, the battery will die in less than half the normal time.

We can't do anything about this, it is a characteristic of how the phones work, but by simply turning the transmitters off (putting it into Airplane mode) when we know cell reception is spotty, we can stop the phone from constantly searching for cell towers, and this stops the battery drain.

Hope these suggestions help.

Michael