Google has recently added its Google Now service into its search app for iOS, but there's one big drawback to getting constant weather, traffic, and other local information on your phone: Location Services runs constantly. You can tell by the little arrow icon up in the corner of your home screen. Usually, that service only flips on when your phone needs to know where it is, but Google can be greedy with that information, keeping your Location Services on all the time, and thus draining your iPhone's battery much faster than it would otherwise.
So what's the solution? Inside Apple's Settings app, you can manually turn off Location Services for each app that uses it, so if you want to keep Google Now from draining your battery you could turn off Location Services altogether. Another approach, suggested by Mac OS X Hints, is to turn off the Now feature within the Google Search app, and only re-enable it when needed. Not the best solution, but it works for sure.
Our commenters point out a somewhat less draconic approach to toning down Google Now's location access: in the Privacy settings within the Google Search app, you can disable Location Reporting. With that option turned off, Google Now won't keep track of your location in the background -- it will only check when the app is actually open and in use. This may decrease the utility of the traffic cards, for instance, but it should help battery life.
I had the same issue, actually, with Google's Field Trip app. I thought the app worked great, but it definitely drained my battery, and the constant notifications got to be a bit much. The solution I found there was simply to sign out of the app when I didn't want to hear from it, and that's worked all right; it does reduce the spontaneous discovery of nearby attractions that Field Trip tries to deliver, but that's a trade I am willing to make. Ideally, both of these apps would have big on/off switches included, so users could make sure the apps were only active when they were needed.
We should note that Google's help document for Google Now suggests that the location reporting feature ought to have minimal impact on battery life, but that isn't necessarily matching up with the real-world experience of users with this first version on iOS. Hopefully, Google will hear some of these complaints, and we'll see the apps work a little less greedily in the future.
Post updated to clarify MacOSXHints recommendation.
Update: Google has gotten in touch with TUAW to say that these claims of battery draining simply aren't true. The company says they tested the apps thoroughly, and while other apps using Location Services may drain your battery, Google tells us that these apps won't. Whether or not you want to leave these services on, then, is up to you. Here's Google's full statement:
Reports that Google Now drains battery life are incorrect. We understand people's concern about seeing the Location Services icon stay on when they use Google Now. Many apps that keep the icon on actually do drain the phone's battery because they require very accurate location. (For example a navigation app has to run your GPS all the time to keep you from missing your turn.) Google Now is built very differently: it uses cell towers and wifi hot spots for much lower battery impact.
We extensively tested Google Now on iOS for months and didn't see reports of significant battery impact -- we would encourage you to try it in the Google Search app for a few days and we don't expect you to see significant impact on your battery. If you are seeing a problem, please do tell us (just tap feedback in the app settings). We take user feedback very seriously.