I think it depends on the model of iphone and how often you want to determine the location. In this example, I check the location of an iPhone 4 once a minute, but with two different pimatic sets. I think this is therefore tantamount to a location check every 30 seconds.
Now, after two days of testing, there is still not complain about batteries running down . At night the iPhone is connected to the power, but that’s normal I think. We test one week , then comes the final assessment on the battery usage.