[Optimus One, P500, V General] Whyzor:
I decided to write a guide for those who are interested in extending their battery life, for emergency situations or for general purpose everyday use. I have the Optimus V specifically, but these could apply to many other phones as well.

Using Inferior Human Organs Cyanogenmod 7.1 ROM on standard 1500 mAh battery

Here are my settings and explanations behind them, prioritized from what I believe to have the most impact to the least.

- No 3G, wifi, BT, GPS unless needed by toggling in status bar

I have the notification toggle set in CM7 settings to set/unset these all with 2 swipe actions, so it's very convenient. 3G data uses more power than wifi, by turning it off, it saves a lot of battery. To get immediate msgs through, I set SMS notifications for FB messages, Google Voice SMS forwarding, or even email notification from certain people. SMS runs off the cell phone network instead of the more battery intensive data (2G/3G).

- Light SMS, occasional phone call, and browsing through Opera Mobile browser

By letting SMS & phone calls ring like normal, it still allows important messages through. Instead of installing different apps like FB, traffic, weather, gasbuddy, I have those sites bookmarked. Using Opera Mobile Turbo technology also saves on transferring data (it compresses webpages on remote server before sending).

- Airplane mode for sleep & work hours.

I don't want to be interrupted during certain hours of the day, might as well turn off the radio. However if there are no rogue apps running the background, idling even with a cell signal should be less than 1%/hr.

- Lowest brightness in most indoor settings. 50% in outdoor bright areas. I enabled CM7 setting to allow drag notification bar to set brightness easily.

- Data sync, animations, clicks, vibrations all off

Whenever the CPU does extra processing, it requires higher frequency CPU, so getting rid of the eye candy focuses the processing to just the important tasks. Also audible clicks & haptic feedback uses extra battery power. Motors (for vibration) typically use a lot of power compared to audio & CPU processes.

* 122-480 InteractiveX governor

Power consumption formula is P = C * f * V^2 (where C is constant, f is frequency, V is voltage). Voltage normally has the highest impact but the OV only has 2 steps, 0-480 Mhz is the low step, above 480 is the higher step. 480 Mhz is fast enough for everyday non-gaming use.

Interactive or InteractiveX (locks sleep freq to lowest) ramps up faster than default ONDEMAND governor, and still scales down when not much processing is needed.

- Bloatware removed, no battery manager/task killer of any kind either

Don't install any app that you don't use regularly (or freeze them). They can easily prevent the phone from sleeping properly to conserve battery. Use BetterBatteryStats to find those misbehaving apps & uninstall them until the developer fixes it.

- Turn on airplane mode in weak or no signal areas

A cell phone searching for signals can drain the battery pretty quickly. Not only does it transmit at maximum power, but it does it frequently to try to re-establish a connection with a tower. So if you know you'll be in a weak/no signal area for a while, just disable it.