Would this cause my battery life to go bye bye?

All models of the iPhone from the beginning of iPhone time (29 June 2007) have had rapid battery discharge incidents occasionally. This is your turn. It isn't related to any specific version of iOS and hasn't been cured by newer versions in the past. The only thing that resolves it is identifying the app that is causing the drain. With almost 500,000 apps available that can be a challenge. However, the prime suspects include email (especially if you have an Exchange or iCloud account), contacts, calendar and game center, among the built in apps, followed by apps that update in background (social networking, primarily), then apps that use Notifications such as news apps. And streaming apps, of course, if you don't shut them down.

Restoring as New is a good test; if the battery still drains rapidly after the Restore and before you add any email accounts or apps it is likely a hardware problem. But this is rare.

1 Double Tap Home - Hold One on MultiTasking to wiggle them

2 Press the Stop button on every single one of them you're not going to use. Background Applications including Navigation, Location Services, and more utilize a great deal of your idle battery power even on background frozen.

3 Also, you can do several tweaks.

Settings - Mail - Fetch New Data - Hourly

Brightness - Half Way

WiFi - Off (when never at a WiFi station, don't bother having it on) (even turn off "Ask to Join Networks")

Airplane Mode - ON (If your iPhone doesn't work from time to time, mine doesn't in basements)

4 Add a battery pack - I use my apps frequently and drain the life out of it. Battery packs help.

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Note that it's a good idea to be sure you saved your camera roll and store them into your photo library for the ones you want to keep. Your camera roll has limited memory compared to your hard drive space.

Unplug it, then plug it in again for 30 minutes. If it doesn't come up to 100% and it gets hot during those 30 minutes you have something running in background that is using more power than the charger can supply. If it stays cool and doesn't come up to 100% you probably have a bad battery. Take it to Apple for replacement.

It can be normal to be at 96% after charging in one situation. When it charges and reaches 100% charging stops to protect the battery. If you have background processes that use battery power the battery will start to discharge, and the charger won't come on again until the battery drops about 5%. So a battery level between 95% and 100% after charging is not necessarily abnormal. Unplugging it and then plugging it in again starts charging and should bring it up to 100% in 30 minutes or less.

I've found iCloud to be both a battery and data hog. Especially iCloud email. My average data use has been under 200 MB/month. Last month I subscribed my iCloud email to a listserv that delivers 3-4 large messages (~50K) a day, and my data usage went to 700 MB. So I've stopped using iCloud email. (I have a grandfathered unlimited data plan, so I don't care about the data volume, but the battery life hit was noticeable).

iCloud must be very inefficient, because 50K x 4 x 30 is only 6 MB; why that should require an additional 500 MB or data is a true mystery.

Sounds like a plan. Let the battery drop to zero and recharge. Just keep using the phone until the screen goes blank. Ignore the low batt warnings.

Yes, a Restore would be a last resort. FYI, mine loses less than 10% overnight.

I agree about a Restore. Restore as New and see if the battery drains before setting up email or adding any apps. If it does you need to get it exchanged by Apple. If it doesn't try adding your email accounts one at a time, then your apps.

I have no idea what mine does overnight, because I charge it overnight, every night. For 5+ years now.

Hey i recently got my 2nd replacment 4s and decided to do some tests on it. Starting with a DFU reset and not adding icloud or any back up, just music from itunes and contacts, i started testing each feature over night. We should be able to say these are what all the 4s' should expect in performance. So i charged it to 100% and then let it drain over night (8hrs) then used it normally to drain it thru the day.

Setting Drain Total standby possible(hrs)

No settings active <1% >800hrs

Bluetooth only >3% <266hrs

Wifi only (ask to join on and off) >12% <66Hrs

Wifi only (no network connected). <1% >800hrs

Siri only <1% >800Hrs

Data (3G) only <1% >800Hrs

Location services (all services on) <1% >800Hrs

Wifi on plus all options >15% <53Hrs

3g data on plus all options <1% >800Hrs

Wifi &amp; all options(no blue tooth) >14% <57Hrs

Im just starting to add and test my mail accounts and then icloud after that. Let me kno if u want me to try any settings or explain which settings i used. Might serve as a gd reference to people who thing theres something wrong... Except mine could have something wrong too... For instance my wifi shouldnt drain the phone that much and would be good to know if any 1 elses does.