I hate battery life threads, but I got my G7 Thurs afternoon and battery has been pretty disappointing.
Unfortunately under battery, the LG home launcher is the biggest culprit, at times showing as 30%. Even if I'm using a different launcher it still shows up number 1 on the list.
I'm guessing there is a way to use ADB to debloat or disable some of the apps.
Aside from that, really happy with the phone.
1. You have to wait several weeks so that Android can recognize your habits and optimize your phone.
2. Download LG Package Disabler Pro and disable useless LG and bloatware apps that you're not using. There's money back guarantee so if it doesn't work, you can get a refund. Works great with my V20, no need for rooting or any other mods, works straight out the box (this is better than using ADB to disable apps, it's easier and less likely to cause corruption/errors, and best of all, you can re-enable apps whenever you want).
3. Uninstall apps you don't use such as Google Hangouts, Google+, Google Newsstands, Google Play Music, LG SmartWorld, your carrier bloatware (use package disabler for apps you can't disable). Know that these apps run in the background 24/7, sending you push notifications. Consider using a 3rd party Facebook app such as Metal which consumes less battery than Facebook and FB Messenger (or temporarily disable it with Package Disabler when not in use).
3. Install Greenify and use manual hibernation every once in a while (I use the widget shortcut). Some apps will always auto start (Facebook & FB Messenger) but other apps will not start again until you open it. You can also use LG Package Disabler to temporarily disable apps and then re-enable it later. It also frees up RAM. I don't recommend auto hibernation.
4. Install ForceDoze. Standby time will be improved vastly.. you'll have to use ADB to install it (Google the instructions). ForceDoze forces the phone to go into Doze Mode immediately after you turn off the screen, Doze is an Android feature but only turns on after a long period of inactivity.
5. Enable Data Saver mode.. it will restrict apps from using mobile data (you can customize which apps you allow).
6. Check your mobile data settings and make sure they're correct, sometimes the phone is searching for a signal in the wrong towers and that kills the battery.
7. Consider turning off WiFi and Data off when not in use, I think all LG phones have the data on/off toggle shortcut.. AT&T and Samsung removed that shortcut. You can go to WiFi advanced settings and have WiFi turned off automatically when the screen is off.
8. Disable OS animations: go to settings > about phone > software info > then click build number 5 times. Then go back to settings and you'll see developer options. Turn developer mode on and scroll down to window animation scale, transition animation scale, and animator duration scale.. turn them all off. Might save a bit of battery by taking the GPU load off from the animations from the OS plus it'll be super speedy fast when you're navigating through the OS.
9. The G7 has a new ultra bright mode, don't use that unless needed. Try to use lower brightness.
10. Enable "Battery Saver Mode", I've experienced 1.5-2x battery life with it on. It's actually not that slow (unlike Samsung's battery saver mode), can't tell the difference in speed. Make sure it's set to "always on" when it's enabled.
11. Turn off OK Google voice detection. To check if it's on, say "OK, Google". Kinda creepy it's on by default and Google is hearing everything you say.