[Galaxy S I9000 General] nanolite:
My first post. Wonderful forum.

My battery can last up to 2 days.

The eternal struggle for a longer battery life is a matter of priorities when it comes to phones like this (OLED/3G/BT/WLAN/RAM). I prefer longer battery time, so I don't mind not exploiting all the features it offers on my homescreen. Not all will share my priorities, nonetheless, I wanted to share my thoughts on this matter as it might help someone.

SCREEN:

Pixels in Super/AM-OLED generate their own light, as opposed to LCD screens which require a light source, backlight, to illuminate the RGB pixles. This light source might be CCFL or LED.

Because black pixels in LCD screens will be equally illuminated as the white pixels (not entirely true with LED backlight) it really doesn't matter if you are viewing a dark or bright picture because the battery consumption will pretty much remain the same.

Black pixels in OLED screens are simply turned off OLEDs (Organic Light Emitting Diodes), thus the superior black levels. This means that the red, green and blue diodes are not powered on, thus not consuming any power. White pixels in OLED screens however consume between 90% - 100% (approximations) of their total power consumption potential, depending on the screens brightness level, because the RGB diodes are required to run on max strength to produce white light. So it will be a tremendous difference between a dark image compared to a light one in terms of power consumption.

Preventive measures for screen related power consumption:

- If you look under Applications > Settings > About phone > Battery use you might get an idea of how important this is.

1) 10% screen brightness for general use. You don't need more screen brightness indoors because of the Super AMOLEDs excellent performance. You might need to turn it up to 100% in very sunny conditions.

2) Black background homescreen. While this Super AMOLED screen is the best one for viewing colorful images, there is really no need to have a cool background wallpaper, especially if you spend allot of time in the home screen. The gallery is for viewing images and showing off ;)

3) Use apps which are capable of using a black color background and white text/buttons, especially if you use that app allot. One example is for me is that I use FBReader instead of the included Aldiko ebook.

COMMUNICATION:

WLAN/3G/GPS are power consuming communication types, especially in phones with widgets/apps/services which are able to sync with various internet services/communities to provide us with information. For mobile phones this matter is a bit special because a phone can have good reception in one location and a bad reception in another location 3 meters (10 feet) and thus requiring an additional process of retrieving connection to a WLAN/3G network.

I really don't need any constant sync such as Facebook/Twitter, a newsfeed or a weather widget which tells me what the whether is outside my window. I especially don't need these services running while my phone is in an idle state. I need 3G communication when I'm surfing the internet to find information I need, such as directions, email or download apps. These are my personal preferences however.

Preventive measures for background communication power consumption:

4) Turn of WLAN while in idle and when you are not using it.

5) APNdroid. A wonderful app which disables 3G communication. It is able to restore it on demand. Some have reported that it does not restore 3G communication and they are required to reboot. I'm using SGS and I don't experience this problem, it takes however more time to turn it on than turning it off.

MEMORY:

RAM, Random Access Memory, is a very fast kind of memory compared to the memory used for storage. This is why you have hundreds of GBs of storage memory and only a couple of GBs in RAM. You also have hundreds of GBs of storage memory because it's cheaper. RAM also works in a specific way in computers; it constantly needs power supply to maintain the data in the memory. If same principles govern our SGS with 512 MBs of RAM, then you surely don't want any unnecessary apps/services running in the background.

Preventive measures for potential RAM related power consumption:

6) Install an "App killer" app and use it. I use Advanced Task Killer, it's free, it can automatically kill apps at various intervals or events. It also has an Ignore list for apps you want it not to kill.

I agree with FrezoreR and not you because all these sources suggest same or similar (not opposing) methods to prolong battery life:

1) wikipedia-link

2) howstuffworks-link

3) batteryuniversity-link

Cant post links yet but you can look it up, search with Google for Lithium-Ion battery chemistry or care.