When I got it 2 years back my Samsung B2100 had a 4 day battery life even with regular calls. The truth is batteries wear out and need to be replaced. Recently, I was charging it every few hours. If I thought my new Razr was going to spare me the routine, I was sadly mistaken. Motorola recommends charging it every night and so far that has been exactly the way it works out.
I am not complaining, this is characteristic of smartphones, what is cool about the Razr though, is that there are plenty of ways to save the battery.
Firstly I turned off all services that I don't use a lot. like GPS, bluetooth, and wireless. You can actually put little toggles on the Menu screen that allows you to turn them on and off easily. Next I tapped to Settings-Data Manager. My thinking is that any excess of data service use will use battery too (more on limiting the data usage lin another post). The Data Saver goes on. At first I turned off Background Data but then noticed I don't get 3G with this off.
If you tap your way to Menu>Settings>Battery>Information>Battery Usage, you get a nice readout of who is spending your battery power. Tap any of the items and you get usage details and sub menus (Display settings under display for instance) that help you set up battery saving measures. Very cool. The biggest culprits are unfortunately one's you can do little about, the Android OS and Voice Calls.
The display comes third, and you can play a bit with the settings to get savings. Obviously the longer the backlight stays n the more juice you use. The manual suggests setting the diplay Screen timeout short, but setting it to 30 seconds (the shortest) gets really irritating. Best to find what works for you. I set mine to 1 minute which is irritating but bearable. You can also go to Brightness to adjust the level which also saves some juice. Tap Animation > No animation to turn off Menu screen animatons and save a sip of juice.
Best advice is to put the phone to sleep as soon as you put it down by pressing the power button. If you pop the phone in your pocket, a sensor on the front will imediately put it to sleep in the dark. This means you cannot use the phone under the blanket in the day, it just turns itself off. Luckily this function can be disabled, (Display>In pocket Detection) and it is clever enough to know when it is night time (or else it would turn off whenever there was no ambient light).
It lists Phone idle as number 4. After a laugh at that I figured probably all standby time is accounted into this usage and not, as I had first imagined, that an idle phone uses more battery than an active one.
The Razr has a useful app called Smart Actions that allows to you to set triggers and actions. I have not used it much, but the Battery Extender rule sets up to turn off the GPS and Background synch when the display is off, and the phone is not charging (ie if it's in your pocket). I'm still exploring the other rule and in fact the app makes suggestions after a while based on how you use the phone. The sample rules don't seem to make sense but you can customise the rule so I'm playing around with that.
I'm off to play some more.