Battery consumption between GSM (2G) mode and WCDMA (3G) mode

I notice that the battery life of my phone can last longer when it is in GSM (2G) mode than WCDMA (3G) mode.

Here is a simple observation of its battery consumption pattern. I switched it to GSM mode (Settings > Wireless & networks > Mobile networks > Network Mode > GSM only) during day time, and switched it to WCDMA mode (Settings > Wireless & networks > Mobile networks > Network Mode > WCDMA only) before I slept, and switched it back to GSM mode again the next day. Along the whole period, there is no phone call.

Here is the battery consumption pattern I get:

and here is the same graph shown in landscape view:

It is very obvious that when the phone is on WCDMA mode, its battery consumed faster.

This is an HTC Incredible S upgraded to Gingerbread Android (version 2.3.3). I do notice that when it is in GSM mode, the signal is pretty stable (I can always get a full bar), and when it is in WCDMA mode, the signal is not that stable (there are frequent occasions of losing one bar or two bars). Probably the stability of the signal is one of the major factor in battery consumption.

Anyhow, it is a known fact that the phone will consume less battery when it is in GSM mode rather than WCDMA mode, and it is among the tweaking of battery saving apps such as Juice Defender.

App: Yahoo! Mail for Android is a battery sucker

Yahoo! Mail for Android is an app developed by Yahoo! Inc. to access Yahoo! Mail accounts directly from the smart phone.

There are quite some feedbacks in Android Market complaining that this app is slow, but I didn't experience any obvious slowness in my HTC Incredible S.

Despite that, I've uninstalled Yahoo! Mail because it consumed too much battery, and I couldn't find any setting to fine tune its battery consumption, such as controlling its sync behaviour.

Before I installed Yahoo! Mail, my phone will consume about 7% of battery at night during my sleep. After installed Yahoo! Mail, I noticed the battery consumption had gone to 14%, doubling up the original, and after I uninstalled it, the battery consumption now gone back to 7% during sleep again.

Looks like Yahoo! need to pay more attention to their QA before releasing the app.

Solution for Samsung Galaxy Tab unable to turn on problem

If you own a Samsung Galaxy Tab, have you ever encountered the problem of unable to turn it on after you off or reboot it?

The symptom could be:

• You press the Power button. No matter how long you pressed and how many times you pressed it, nothing happen. Your Samsung Galaxy Tab remains dead with a black screen.
• You press the Power button. It vibrates. But then it is dead again.
• You press the Power button while charging. It shows the battery charging icon for a while, then it is dead again. 
• You press the Power button. It freezes during boot up.

If you encounter this kind of problem, don't give up yet! Try this:

Touch any part of the screen with one finger, at the same time press the Power button. Wait for a while (and pray - might take up to 2 minutes). Your Samsung Galaxy Tab might come back to life again.