Why does my iphone 4's battery need charging 3x a day?

I got it at Christmas of 2013 and it did good for a couple of months. But now it need charging 3 times a day, maybe 4 or 5. Is there anything I can do? Because I don't want to get a battery case because I bought a otterbox defender and a otterbox reflex and a lifeproof case.

Replace the battery & get on with your life.

It is likely there's an application you downloaded that needs to have the radios on all the time. You need to quit them… Go to Settings - General - Background App refresh. Turn off the ones you don't want on.

If you don't use a Bluetooth device, turn Bluetooth off: General - Settings - Bluetooth.

When your phone is not being used as a hotspot, turn off Personal hotspot - turn it on only when you need it.

There may be more - these are a good place to start.

Heres a battery tip, charge your battery at 20% or lower but don't let it go completely flat, rechargable batteries have a cycle, if you charge your battery at 20% or more your battery isn't completing its full cycle which means you will have a shorter battery life, where as charging it at 20% or lower will give your battery a better lifespan and also battery life over time.