The German iOS developer also found out that WhatsApp consumes a lot battery. WhatsApp after your close it by pressing the home button, it stays active for 10 minutes communicating to its server instead of using iOS’s native push notifications. Here’s the dev explaining it:
WhatsApp for example. When it seems like it’s terminated it’s actually running exactly those allowed 10 minutes and continues to communicate directly with it’s server instead of using iOS’ push notifications. That’s draining more battery, of course.
So if you are getting a message in this 10 minute timeframe and open WhatsApp, this 10 minute period starts again. That means if you are getting lots of messages it could happen that WhatsApp is running the whole day.
To fix this issue you have two options. For Facebook, you can delete the app and use Facebook on Safari. But to fix it on both apps, all you need to do is completely close the apps by double tapping the home button, holding the app until it jiggle then hitting the minus sign to close it.
(Source –Â blog.hagga.net)