It might seem counterintuitive to run an app on your phone or tablet that pinpoints which other apps are hogging all the battery power.
But that's the easiest and most efficient way to find out.
Battery Doctor is a free iOS and Android app that offers users a complete set of tools to manage their phone's battery life.
It'll point out which apps are the biggest power sucking offenders and advise you when it's best to recharge.
Battery Doctor will also offer tips for saving battery life.
For example did you know that disabling automatic time-zones on your iPhone can boost your battery life by as much as 30%.
If an iPhone user wants a simpler experience try the 99 cent Normal app.
After running in the background of your device for a few days it sends usage data to its servers to be compared against other phones.
Then you'll get a detailed report about the biggest energy draining apps on your phone, and how much more time you'd gain if you close them or deleted them all together.
In San Francisco, I'm Kara Tsuboi, cnet.com for CBS News.