Why does my iphone 4 die so quick?

I recently bought an iphone from amazon and it was at&t so i had to unlock it because the service i have is lycamobile.i've noticed that my iphone dies VERY quick.i'll charge it all night and wake up with 100% then within 15-30 minutes it's about to die. Sometimes it will just die at 40% or when it's completely dead i will plug it up and it will say it's on 77%? My brightness is low, i close all my apps by holding the home button until they shake and minus them away.don't use Wi-Fi. It's very weird and i don't want to have to get a new battery because that will be so much work. Is there anything i can do to fix this? Anyone know what the problem is?

You either have a bad battery, or you have to many apps running at once, or a certain app itself if taking up a lot of energy which would probably be face book, i would suggest updating apps, and deleting unwanted apps.

Well obviously I would say that your iPhone's battery is pretty much shot, you will probably need to get it swapped for a new one. As for things you can do to keep it on until then? Only use it when really needed, then turn it off, have everything at its lowest setting (brightness low, vibrate off, volume low, wi-fi or cellular data off if you are not using them, etc.), always close the apps out from your multitasking bar, and do not turn on LED notifications. Hope you get your phone fixed.

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