7 Replies Latest reply: Jan 23, 2011 4:04 PM by modular747
B-Man Level 1 Level 1 (110 points)
I’m curious, how many milliamps does the iPhone 4’s GPS take up when running Google Maps GPS for an hour?

Dell Optiplex 880, Windows 7
  • modular747 Level 6 Level 6 (18,050 points)
    Since there's no way to measure current draw in milliamperes while using Google Maps, there's no way to answer that. Besides, the current that Google Maps draws varies considerably depending on your location, speed, access to GPS satellites, and cell data network.

    Message was edited by: modular747
  • B-Man Level 1 Level 1 (110 points)
    I apologize, I didn't know the Google Maps draw varied on location, speed, and what not. I thought with the GPS on, it drew a consistent amount of power.
  • DCGOO Level 3 Level 3 (760 points)
    The GPS portion of the consumption IS likely consistent. But the rest of the phone varies quite a bit, and there is no way to separate the two for measurement purposes.
  • Rudegar Level 7 Level 7 (23,570 points)
    the more satellite fixes the gps have the less cpu it use trying to process gps signals trying to get more fixes so more stable fix points the less power is used

    speed the faster you go the faster google maps have to download new images over 3g which again use power

    3g the more constant a 3g signal is the less power is used looking for a connecting to a new 3g antenna

    even on computers where more options are present then that of a phone I've never seen a program which could show just how many watt a program was using at any point
  • modular747 Level 6 Level 6 (18,050 points)
    The GPS portion of the consumption IS likely consistent.

    No. Location Services, which uses GPS and other methods does have a minimal draw just by being enabled, but uses extra current only when actually being called to fix a location. When used by Maps (Google Maps), this only occurs when moving or manually requesting a new fix.

    The amount of draw also depends on access to GPS satellites and/or WiFi or cell network location info and need to obtain new map info from Google (not stored in phone).

    Message was edited by: modular747
  • B-Man Level 1 Level 1 (110 points)
    Hmm I was told the following somewhere else...

    "GPS in the iPhone 4 is a Broadcom BCM4750 which is spec'd at less than 15 mW. Assuming 15 mW power consumption with a 3.7V battery that works out to 4 mA."
  • modular747 Level 6 Level 6 (18,050 points)
    Several errors in your calculation, even assuming your specs are correct:

    1. The actual supply voltage isn't the nominal battery rating, it's regulated down.
    2. The power rating in the maximum when in use, not continuous. It only runs when called by the app using in (in this case Maps).
    3. The "GPS" chip is only part of the A-GPS nav system which also uses the cell network and WiFi radios to locate - additional power use.
    4. Maps also uses the cell network or WiFi to download the map itself from Google - additional power use.