Agreed, the wifi *should* go to standby when the iPod sleeps, and I'm sure that it did with the previous version of software that was on the device, but I'm not yet convinced that it is doing so correctly, with iOS 4, so at the moment, I'm still checking battery drain with various settings on or off, and the jury is still out on this one ...
Arfa
I think you'll find that Google know about an awful lot more wireless access points, than just ones that have been registered. There's recently been a big privacy hoo-hah over here regarding the fact that when Google drove their camcars round every street in the country, as well as taking pictures, they also continuously sniffed wireless access points, and logged their locations, and every bit of data they could gather from them.
Big Brother cometh, or what ...
Arfa
On Sat, 26 Jun 2010 01:16:20 +0100, Arfa Daily ??o??:
Looks as you've isolated it. I disable BT on my phones unless needed. Makes a significant enough impact on idle time to do so. Disabling the wifi on my Dell Mini gives me roughly 30% more battery life. I often take it with me when I go looking for things to photograph. Pull the SDHC card from the camera and insert into the Mini and review them. Don't need radios rinsing the battery when I'm out in the middle of nowhere. And I often ride the Harley when I go nature photogging :) No cig lighter power supply on it.
I've definitely isolated it now. It wasn't the "Location Services", it was "Notifications" as someone else suggested it might be. I now have wifi set back "ON" and location services set back "ON", and everything is just fine. Battery life is absolutely normal. As soon as you switch "Notifications" back on, the battery rinsing starts. I haven't a clue what it is for, and I'm sure I don't remember seeing it being on, or even actually there ?? in the previous version of OS that was installed before the iOS 4 upgrade. Anyway there is no problem with operation or battery with it off, so off it will stay ... :-)
Arfa
Push Notifications are messages from applications that go merrily out to the internet to see if there's anything worth bugging you about. The notifications can appear BEFORE you smear the screen with "slide to unlock". Under Nofifications, I have eTrade and eBay notifications enabled on mine. I get plenty of notifications from both of these apps.
However, it doesn't kill my battery. I leave 15 minute Notifications on continuously, and my battery level is roughly where I left it the previous night. No unusual drain from Notifications that I can see and I have a rather old battery.
If you don't see any applications listed under Notifications, then turn it off. You don't need it. If you do want the listed apps to bug you when appropriate, leave it on.
On Sat, 26 Jun 2010 19:54:41 -0700, Jeff Liebermann ??o??:
Wonder why these would 'rinse' Arf's battery and not yours?
(...)
Why? It's an Apple product. It's so intuitive and easy, you don't need to know why.
I ran a crude test last night. At midnight, my iPod Touch 2G showed
97% battery charge (using iSystemPro). 9 hrs later, it's at 89%. Notification is set to check my stocks and eBay items every 15 minutes via Wi-Fi.Here's another app to help run the battery down:
Much like LoJack for iPod Touch, iPad, etc. I just installed it.
Yes, it's odd, but it is definitely the cause. There was one app listed, which is a Caesars Las Vegas 'in house' thing. I don't recall it ever having told me anything though. It's been on my Touch for a long time, and has never caused a problem in the past. It's not an app that I use anyway, so maybe I'll just remove it .
Arfa
Time will tell but it's either a bug or a feature in ios4.
That push notification stuff came in with one of the 3.x updates, but like you, never saw any useful using it, at least on the ipod touch. I had about
8 or 9 apps that had push in them but only one would randomly get a message.But the behavior with the wifi when it's sleeping is changed with the 4 from the 3.x stuff.
I noticed it because the router I use for the dsl has a separate "wireless" light on it, comes on when someone is using wifi. We only have two wifi devices, the wifes laptop and my iPod.
The morning after the ios4 came out I noticed first thing the light was on, still on an hour later. Checked and her stuff was packed away, she was sleeping. The ipod was in sleep mode.
I took a quick look at the local network map on the router and sure enough, it showed the ipod active and on the wifi, nothing else. Turned it off, the wifi light goes dark.
Hmmm.
Turning off the push stuff made things go back to the old behavior, ipod sleeps, the wifi light stays off on the router. If it comes up once in a while, I don't know, never noticed it.
Only thing I can figure is, with the 3.x if the ipod is sleeping, you just wouldn't of received push notifications. Maybe now you do with the ios4. Even with it sleeping, it keeps the wifi in a listening mode or something.
-bruce snipped-for-privacy@ripco.com
Hmmm. Your experience would seem to mirror mine then. I too noticed a lot of wifi activity on my router, but I have all sorts of machines connected wirelessly, and they are forever doing things in the background, so I never took too much notice of it. Anyway, seems like we've both found the cause of the problem, and the fact that it is dependant on apps that want to use the facility, would possibly explain why some iPod Touches are suffering, and some are not. My wife's is identical to mine, but she has not had the problem since updating. I checked the Notifications on hers, and nothing showed as wanting use of the facility. I shut it off anyway though, as she is a bugger for downloading free games from the Apple store ... :-)
Arfa
Argh. I installed iHound to send their server my location every 10 minutes. The default was 3 minutes. I left iHound running overnight. The battery went from 97% to 32%. Ouch.
I don't think it's Notifications that are sucking the battery power. Methinks the problem is leaving an application running that uses notifications or just CPU cycles when the iPod Touch is in standby. I usually display the desktop before turning off (actually standby) mine, so I haven't had much experience with what an application can do to the battery level if left running.
No apps were running to the best of my knowledge, when the problem was occurring. I installed an app that monitors the system processes, as well as a lot of other things like the battery, and checked what the state of play was before putting it to sleep. It showed the processor as being (typically)
96 - 97% idle. There was one app that *wanted* notifications access, but the app was not running - or at least it wasn't running in the foreground. Nothing had changed with this app or the way it was loaded, and it had not caused a problem before. Maybe iOS 4 gives it what it wants in the background. I guess this may be a bug, and because of that keeps the wifi running pretty much continuously. I don't know where in the unit the wifi module is located, but certainly, the back of the case was warm enough to just about feel, up near the top. It never had been before, and isn't again now.I have actually deleted the app that wanted notifications access now, so it might be an interesting experiment to turn notifications back on. I guess I could also wave the unit at my spec anny, and see if there is any obvious wifi activity from it, when it's asleep.
Arfa
So much for that theory.
That's what you'll usually see. The iPod Touch does not support (much) multitasking (thank you Apple) so the only application that's really able to run has to be in the forground and running. An application can be installed, but unless it has Steve Jobs personal permission to run in the background, it's not going to burn any CPU cycles.
Looking inside:
the wi-fi chip is near the top, next to the antenna:
next to the gold test coax connector. Mouse over the Broadcom chip in the right hand photo above the "Step 10" label.
A passive Wi-Fi sniffer (Kismet) might show more. Spread Spectrum is difficult to see on an SA. If Notification is on, you should see some traffic when it wakes up. However, if you REALLY want to run the battery down, turn off you wireless router at night. The iPod Touch will try to find something with which to connect. Not finding any open access points, it will go through the list of SSID's heard, thus taking more time, and much more battery power.
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