I've seen a few threads on other forums about this, but here is what I'm observing. When Wifi is turned on, the 3G (or 4G if lte is enabeld) sometimes stays on. Sometimes it changes to white (indicating that it may still be connected, but not syncing to google through that connection), sometimes it stays blue, and once in while it actually goes away, but not often.
Some other threads seem to indicate that this is just a display bug. However, if I analyze my battery stats, I think the connection is actually staying on. Here is what happens:
- With just a plain 3g/4G connection and no wi-fi, if I look at the battery stats for Cell Standby, the "time on" increases as expected. If there was a period when the cell signal was dropped, I will also see the percentage ot time without a signal.
- When I turn on Wifi and the 3G icon stays on, if I look at the battery stats, the Cell Standby's time on continues to increase, but not the "percentage of time without a signal" also increases. This seems to indicate that the cell signal is staying on, but it knows it is not connected and is searching for a signal. I'm not sure if this is actually eating up more battery like when you really don't have a signal and it is searching, but it is being reporting that way at least.
- If I install a widget to disable 3G/4G while on wifi, the icons go away, but I still see the same thing happening in the battery stats. This could indicate that it is still connected, or it could invalidate what I'm seeing altogether, not sure.
In any event, I'm not sure what the real story is here, I never had the icons stay on with previous devices (Droid X and X2), so I never investigated the battery stats. However, I see alot of people talking about their Cell Standby taking up a lot of battery, I wonder if this plays in to it.