[Nexus 5 Q&A, Help & Troubleshooting] TheContinental:
Every Battery Tip I Know for Nexus 5 w/Lollipop

Following the steps below, I now get more than a week of battery life in standby.

The biggest battery drain culprit during idle time is behind-the-scenes software — continuously running, polling the Internet, or updating. On a Google device such as the Nexus series, most of that power-hungry activity comes from Google itself. Before we get to the Google stuff, let’s tweak some overall settings and Play Store settings to reduce battery drain in those areas:

First, let’s make sure you’re on the latest OS version for the Nexus 5. In Settings, swipe down to About Phone, choose that, then swipe down to “Android version”. When I wrote this in mid-February 2015, the latest OS version was 5.0.2 (I have a custom ROM). Check for OTA updates on the same screen, and update to the latest OTA version if necessary. If rooted, feel free to install the latest custom ROM of your choice.

Once updated:

Hit your Play Store icon. Click the three-bar menu at the top left. Select “Settings” near the bottom.

Under “Auto-update apps,” choose “Do not auto-update apps.” (Why? Because that “feature” uses battery juice to download and install stuff whenever it feels like it, instead of whenever you say.)

On the same page, under Notifications, make sure “Notify me about updates to apps or games that I downloaded” is checked. That way you will know if something needs updating.

On the same page, uncheck “Add icon to Home screen for new apps.” Because it’s annoying, not because it uses battery.

While in Settings, let’s turn off some radios:

Go to your phone's Settings.

Choose “Wi-Fi”.

Tap the three-dot symbol at top right.

Tap “Advanced.”

Make sure “Scanning always available” is unchecked.

If you don’t travel much with your phone, disable Location (GPS). You can always re-enable it on demand.

If you don’t use Near Field Communication (NFC) for tap-to-pair features, disable that. You can always re-enable it when ready.

Disable Bluetooth when not using it.

Obviously, keep your device’s screen brightness as low as is comfortable. (The display is the biggest power hog on your device.) You can change the display brightness settings under Settings, Display.

While in Display Settings, disable Ambient Display. (Well, first Google it, because you might actually like the feature.) But it does use battery.

In Settings, under Sound and Notification, go to “other sounds.” Uncheck “Vibrate on touch.” (I have this setting on a custom ROM. I don’t know if the OEM ROM has it.)

When disabling or uninstalling Google apps, DO NOT uninstall anything essential to the smooth running of your phone. That includes:

Google Search

Google Chrome (unless you replace it with another browser)

Google Settings

Hangouts (you can disable Hangouts once you've replaced it with an aftermarket texting app)

Google Now (although we will disable many of its features and opt-out later)

Google Play

Gmail

Any app that doesn't have an "uninstall" option, unless you know what you're doing

Now let’s clean up a few apps. We will stay away from system apps, such as Email — because people can get into trouble uninstalling essential system apps.

It’s tough to keep up with every app working in the background or polling the Internet. This thread lists many ways to monitor and disable services. Also, in my opinion, you should uninstall any app that you didn’t specifically put on the phone yourself (system apps not included). This assumes that the app allows you to uninstall. System apps and a few others will only allow you to disable them. For example, I uninstalled:

Google Earth

Google +

Hangouts (after I replaced it with Textra)

Google Docs

Google Drive

Google Sheets

Google Slides

Google Fit

Plus, any downloaded apps I’m no longer using, such as wallpaper apps.

For traveling smartphone owners, Google Now can be a godsend — always reminding you of what’s next, keeping you out of traffic jams, and keeping you on schedule. However, with Google Now, the Nexus 5 mic is always on and listening for that “OK Google” search command — which obviously uses battery power.

I found that I didn’t need Google Now at home, where my Nexus 5 sits 90% of the time (I work from home). If you’re like me, (or don't appreciate the privacy invasion and battery use), you can opt-out of Google Now — or at least stop the mic from listening.

We’ll start with the least draconian measure: stopping the mic from listening for the “OK Google” command:

From your main home screen, swipe left until you get to the Google Now screen.

Tap the three-bar symbol at top left.

Choose Settings.

Choose Voice.

Choose “OK Google” Detection.

Uncheck both “from the Google app” and “From any screen.”

If you don’t want Google Now at all (I don’t like it because it’s always updating something or doing something in the background), here’s how you disable it completely, while leaving full Google Search (and Voice Search, by tapping the mic symbol) functionality intact:

Start by disabling “OK Google” voice detection as shown above.

Then, in your Applications, open the Google Settings app.

Tap “Search & Now”.

Tap “Now cards.”

Uncheck “Show cards.”

You will see a message that asks if you really want to turn off Google Now. Go ahead and do that.

From now on, you can still easily search by swiping your finger up from the bottom of any Home screen. And you can still do voice searches by tapping the microphone on any Google Search screen.

I hope these battery-saving features do as much for you as they did for me!