Regarding battery life, there are two things to consider.
Firstly as @Fab mentioned yes, naturally it will drain more if there are many background services and apps. Just having Facebook Messenger, Skype, WhatsApp, Twitter and Tumblr drained my battery more considerably. Even if most of them are push-based notifications, they will still drain more battery in the background. So for Android users you'll definitely want to keep an eye on that.
For iOS users you'll probably just want to disable the push notifications in the Settings app or sign out of those applications/
Secondly as @NightDancer and @Caroline alluded to, the battery may be faulty. Particularly if it drains extremely rapidly (sudden drop from say 90% to something really low like 30% as opposed to gradual drop) or if the capacity of the battery has dropped below a certain threshold whilst still in warranty. If you have an iOS device Apple can do an on the spot check for you if you live near an Apple Store.
You'll find that warranty on batteries will always tend to be met with some questioning by the manufacturer as they're generally considered a consumable... for example if the battery reports having over 500+ recharge cycles in less than a year then that would be interpreted as being excessive as normal use would normally be defined as being fully charged within 1-2 days. To get 500+ cycles you'd have to be fully charging 3-4 times a day!
I speak from experience from dealing with Apple's battery policies for MacBook laptops at a school.