Tips on how to saver power, be Green, and extend battery life on Android devices: Juice Defender app review
REVIEWED ON Motorola Droid running Android 2.3, Cyanogen Mod 7, rooted and overclocked, though the tips should apply to all Android devices.
An Android phone or tablet can be a power-hungry device if you use it a lot. So are there ways to stretch the battery life? Yes, there are many apps for this, and some optional hardware. Here we will go over both hardware and software solutions.
Generally speaking, hardware solutions deals with increasing energy capacity (i.e. make the "gas tank" bigger), and software solutions deals with decreasing energy consumption (i.e. make the device use LESS power).
We will also go over a few tips on how to save power.
Update: 26-APR-2011 Revised language, added Q&A and links
There are three ways to get more power... a larger internal battery, an external battery, or more convenient recharge solutions.
Seidio makes a super-sized 2800 mAh battery for the Droid. As it is larger than the regular one, you can no longer fit any regular cases on it. In fact, you have to replace the battery door (but the battery does come with a replacement door as well), and adds 0.9 cm to the phone's thickness. However, you get virtually twice the battery life of the factory battery. If you MUST have a lot of power, this may be a good solution.
If you don't use the Droid, check with Seidio and see if they have a bigger battery for your phone. Alternatively, you can get a second battery and an external battery charger for your phone (see right)
You can get an external emergency battery for the Droid. Something small would be the Lenmar Powerport Mini, or a similar battery, or Energizer PowerPack, and so on. Such devices usually charge through the USB port and you can use the existing Droid AC/Data cable for recharging. Remember, it is an emergency battery only for getting that few final calls out. (see right)
Final way is look for alternative recharge solutions. Always keep the charger/data cable with you. You can use it to smooch power off any laptop with a USB port. If you have one of those Belkin 3AC/2USB adapters (see right) you can use that too. I also have a small 100 Watt inverter in my car that has a USB port output I can use for charging. For emergencies I also carry a 120V-AC to 12V-DC converter in case I have to use my car adapter elsewhere. And finally, the "multimedia dock" AC adapter can be used without the dock.
How *do* you save power on Android device?
On an Android device, most of the power were probably ate up by
- 3G radio and WiFi radio
- GPS and Bluetooth
In Android phones, you can directly view what apps or processes are using your power. Go to Settings / About Phone / Battery Use on your Android device and see for yourself. You can't control power usage in "Phone idle" or "Android system" or "Voice Call" or even "Cell Standby" and "Android OS", but you can control the rest.
To save power on display, it's very simple, actually. Turn down the brightness. Most of the power consumption is from the backlight of the LCD. The lower you set the display brightness, the longer your battery will last. It is that simple.
Furthermore, set the screen timeout faster. Screen off in 15 or 30 seconds instead of 1 minute.
Those with AMOLED or SuperAMOLED screens may benefit from setting the screen to a particular shade of red or displaying a darker themes as the backlight seem to be individually controlled at a pixel level, realizing more power savings. However, that seem to be somewhat anecdotal.
3G and WiFi Radio
Smartphones are "smart" because they are connected to "the Cloud". So you need the data connectivity. However, *most* of the time you don't need it. If you're in the office or home you probably have a WiFi network (and are close to a power plug). In the car you have the car plug. So it is all that "in between time" that you need to worry about.
You can use APNDroid to turn on/off the 3G data connectivity if you are on a GSM phone. Those with CDMA phones should use a similar widget in the free version of Juice Defender. Turn it off means battery savings. You can turn it back on to check mail and such. Some ROMs like Cyanogen Mod let you turn data on/off via a "widget bar" as well.
WiFi is even simpler. Your Android device remembers which WiFi hotspots it had connected to before. Just turn WiFi back on and it'll reconnect. That's in settings.
GPS and Bluetooth
GPS requires detecting and amplifying signals from the various GPS satellites above you, and that takes power. Turning GPS off will save you power.
Bluetooth, while low-powered, still consumes power. If you have no Bluetooth device near you, turn off Bluetooth.
Check the battery usage app to see which apps are eating up your power, then go inside and see if there are ways to disable it from connecting to the cloud, thus saving you battery power.
If you only open Facebook twice a day, you don't need to keep the service loaded so it can update the wall every 5 minutes. Turn off the auto-update altogether and only do manual sync. Same with Twitter and other social networking apps.
Most of the software solutions we review below employs the tips above. Some may also claim to save power to killing background apps and services. That is actually not true. Killing background apps do NOT necessarily save power.
Here are some more tips from How-To Geek explaining what else you can do to save power.
Apps that show power level
The built-in battery indicator is not very accurate. There are various apps and widgets that improves over the original, as well as add additional graphical flairs. Following are merely a representative sample, as there are dozens more out there. If you spot one that's not here, put them into the comments.
An app, a widget, AND a notification bar item, this multi-utility shows power level three ways. The notification bar item shows an icon in the top notification bar, which indicates the power status in 10% increments until it drops to 20%, then it switches to 5% increments.
The main problem with the icon is it's white on dark gray, so it's not very visible. It actually gives you the percentage, like 80%. If you drop the notification bar you get detailed info, like battery voltage, status, and so on. If you select the detailed info, you bring up the app itself.
The widget is a 1x1 area which displays a vertical battery with power level, and if it is charging (shows "power" icon). If you "click" on the widget you bring up the app.
The app itself shows the power level, and the projected battery life remaining based on the activity you perform, customized for the specific Android machine model you got. (You have to select the model, and only a dozen models are available as of now)
Overall, this battery app is quite good, but could be better. The widget look can be improved, and the notification icon needs better readability. There is a paid version, but it was not tested.
Pros: battery life prediction based on activity, notification icon AND widget
Cons: visibility of notification icon not so good, widget looks dated
7.5 out of 10
This is a notification bar icon ONLY. However, it is far more visible than the one in BatteryTime lite. It does not bring up anything else. Updates more often than batteryTime
Pros: more visible notification icon
Cons: does nothing else
6 out of 10
BatteryLife is a 2x1 widget that allows you to configure the colors to display (green, yellow, red, or any sort of color combo). The horizontal battery with level looks much better than any other battery widget available. "Clicking" on widget brings up config editor.
Pros: nice looking widget
Cons: does nothing else, 2x1 instead of 1x1
6 out of 10
BeeBattery (part of Bee Widgets)
BeeWidgets is a set of widgets that has clock (2 sizes), battery, weather, and such. The battery status is pretty simple, and clicking it brings up "battery use" system status. It is simple, and nothing else.
Pros: works, unified look
Cons: does nothing else
6 out of 10
BatteryFun is an app that changes the wallpaper depending on your power level (20% increments). You can download a series of wallpapers from the app, from smileys to Defcon levels to phases of the moon, and more. As the battery level changes your wallpaper will change.
Make sure you set any task killers to ignore this app, or your wallpaper will not change!
Pros: works, great for those with Home++ and not showing the notification bar
Cons: only 20% increment, not always obvious
7 out of 10
Apps that Charts Power
Some apps actually chart your power use (which requires running a service).
There are two of them, actually, BatteryGraph, and JuicePlotter. Both does pretty much the same thing, but JuicePlotter actually integrates with JuiceDefender (see later)
I guess you can use that to tell which period you really use up the power, but that should be obvious, right?
However, JuicePlotter actually use the graph to calculate remaining battery life, and charging time. The more data it gathered, the better it will predict the battery life and charging time. Strangely though, that data is hidden in the "about" screen. On the other hand, you can plant the JuicePlotter widget to show that information as well.
Gingerbread ROM / Cyanogen Mod 7 actually shows a power level graph in the "battery usage" app so you may not need this any more.
Apps that save power
There are many programs that claims to save you power. Only the LITE version were tested.
Keep in mind that many of these programs are just a settings program (turn WiFi off, turn GPS off, turn brightness down...) and a task killer combined into a single app. The apps that truly attempt something new to manage your power use are few and far in between.
Screebl uses your phone's "orientation" to decide whether to engage the
screen-blanker or not, in addition to the usage. If your phone is face
down, for example, it clearly can't be seen, and thus the screen don't
need to be on. Or perhaps the screen was upside down... you get the
idea. It does help, but I couldn't quite tell how much.
Pros: interesting approach on screen blanking to save power, does work
Cons: doesn't work THAT well
7 out of 10
NOTE: Screebl Pro is on sale during the holidays for $1.49 USD.
Juice Defender goes much further in its attempt to save power. It has an easy
mode and an advanced mode. The easy mode automatically manages schedule,
traffic, battery, charger, and screen to presets, while advanced mode
gives you detailed settings for each factor. The latest version V3.2, added a few presets to be even more stringent attempting to squeeze a bit more power when your battery almost gone.
For example, you can set the wifi and APN (data) to be on only when the screen is on. Or define the wifi or APN to be on only 5 minutes every 2 hours for background updates. Or define a cut-off of wifi or APN when battery life drops below a certain point... All are possible with Juice Defender. It even calculates how much battery life it has extended for you.
The "ultimate" version (paid, of course) allows finer controls and three more factors: night, location, and timeout. Ultimate version also allows setting for Wifi and MMS (for example, automatically disconnect APN and turn on Wifi upon reaching known network). Latest version also added "weekend" which allows different peak and night settings for weekends. Support of 4G data control has been added as well, and interface has been revamped.
Problems? Two of them. Software control of APN often requires a rooted phone. Latest version was able to bypass any limitations on my Moto Droid, so it can turn on/off the APN now. Also, the bandwidth limiter seems to have some effect on audio streamers. If you have problem streaming long podcasts and such, turn off JuiceDefender. However, the latest version came with a new setting, call "app", that allow you to define specific exceptions to the bandwidth filter. Still, switching data on/off takes a little time, so if you need instantaneous use of data connection, this may frustrate you.
This is a good way to extend battery life. Try out the regular version
and see how much it helps, and whether the ultimate version is worth it.
Pros: easy to setup, still can customize, demonstratable results
Cons: some settings not quire obvious, esp. what's available and what's not
8.5 out of 10
Battery Fu seem to be a clone of JuiceDefender for older Android phones. However, it needs other downloads to work, and may not be CDMA compatible. Beware.
This app turns WiFi off when there are no networks found, then periodically scans (you set the interval) for WiFI networks. It works, if you stay away from WiFI a lot.
NoBars Battery Saver
If you live in a weak signal area, this app turns on airplane mode for your phone and only turns it back off periodically to pull down notifications, syncs, and voicemail notices, so it doesn't waste power trying to pull down a weak signal. If you don't live in weak signal area this is of no use to you.
Claims to smartly manage wireless data connection and/or WiFi, but basically emulates JuiceDefender with ads.
It doesn't tell you what it supposedly does to save power, nor does it have screen shots. Even its website says "coming soon". I wouldn't bother with this one yet.
Supposedly tells you what's draining your battery as you run, but you can get the same information by going into Settings / About Phone / Battery Usage. "Official homepage" is blank. I'd pass.
A task killer and a settings manager (like QuickSettings ) integrated into one app and lets you do all the work instead of some automation like JuiceDefender.I'd pass.
Same idea, task killer and settings manager into one app, and claims to save battery power.
Yet another task killer / settings manager combo that claims to help you save battery life.
Battery Life (by Mobi Sector)
Claims to save 80% of battery, but doesn't say how's done, nor have any screenshots. Official page goes to an app gallery. I'd pass.
Q: Do Live Wallpapers eat up batteries?
A: Should not do so excessively. The good ones should stop when they detect the screen is off or they have been covered up by other apps. However, some of the more good looking ones do use quite a bit of CPU.
Q: Which use more battery: WiFi, 3G or 4G?
A: 4G is the most power-draining, then 3G, then WiFi. It's a distance, bandwidth, and power tradeoff. 4G gives you great distance and bandwidth, 3G has same distance but less bandwidth. WiFi has less distance.
Q: How do I use airplane mode?
A: Hold power button for a second, then choose airplane mode. It disables all radios inside, so you cannot make or receive calls or get mobile data connection. However, you'll be able to use the phone. That should give you some power savings (and some quiet time).
Download and use both Screebl Lite and Juice Defender to extend your battery life. Use JuicePlotter to get a sense how you're using the power. All are free so you can try it and see if it actually helps or not.
The rest are optional. While the built-in battery indicator is slightly off and delayed, it does work as a "rough" indicator. If you need reminders, then try some of the widgets, notification bars, and whatnot. I personally find them a bit superfluous.
Most of the other apps that kill tasks and such are not needed, and may in fact hurt your battery life as the phone keeps restarting the app or service.
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