voyt92 | # 1 | 2009-12-09, 15:04 | Report

Hi guys it looks like I need your help again, i heard people saying that if you Turn wifi down to 10mW the battery should last longer, the problem is I really cant find where I could do that, could any one post step by step how to do that please.

And i got another question some people been saying after you use wi-fi there is a bug which is going to drain your batter if you doing restart your phone is this true? and also if it is do you have to restart it, or could go to offline mode then back to the normal mode ?

Thanks

Phantasm | # 2 | 2009-12-09, 15:09 | Report

Settings -> internet connection -> any Wi-Fi connection -> edit -> next ... advanced just before clicking finished. There you can find the power setting on 'Other' tab.

As for the bug. Some people have problem with Wi-Fi usage triggering battery drainage bug. Offline mode won't help. Only reboot helps in my case. For more info, see:
http://talk.maemo.org/showthread.php?t=36438

voyt92 | # 3 | 2009-12-09, 15:24 | Report

Thanks mate

ajamils | # 4 | 2009-12-09, 17:14 | Report

is there any disadvantage of turning it down to 10mW ?

That One Guy | # 5 | 2009-12-09, 17:17 | Report

You won't have the range you'd have with it at full power (100mw?). That means you'll have to get closer to the WiFi router you're bouncing off of.

TA-t3 | # 6 | 2009-12-09, 17:21 | Report

For the earlier devices it was said (from Nokia IIRC) that the 10mW setting wouldn't really make any difference for the power consumption, because the data is sent in bursts anyway. The reason there's a 10mW setting is because of legal issues in certain countries (where only 10mW is allowed).

EDIT: Maybe I should add that with the lower setting you risk that your wi-fi connection negotiates a lower data rate (you may be aware of the fact that a wi-fi connection can select different data rates due to signal strenght and quality, e.g. 54/22/11/5/2 Mb/s). So, the lower effect may force a lower data rate, which means longer data bursts and thus more battery usage. Even when taking into account the lower TX effect.

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Last edited by TA-t3; 2009-12-09 at 17:25.

mthmob | # 7 | 2009-12-09, 17:38 | Report

I turned it down to 10mW as soon as i saw the setting on the phone was available, never had connection or speed problems with my home wi-fi.. skype and browsning seems just as smooth as with 100mW settings.

And battery lasts alot better since i changed to 10mW

Phantasm | # 8 | 2009-12-09, 17:55 | Report

Well, for a little calculation... The power usage of the pure transmission power of the Wi-Fi... Considering the change from 100 mW to 10 mW is 90 mW, and the nominal battery voltage is 3.7 V (varies from 4.2 at fully charged to around 3 V when empty). So, 90 mW will on average take 90 mW / 3.7 V = 24 mA. Given the battery real full capacity is about 1260 mAh when new, this gives a time of a bit over 2 days. Of course everything else piles up, so if a random browsing etc on 100 mW Wi-Fi uses the full battery down in 8 hours of active time, it uses about 160 mA. So, in ideal case that the Wi-Fi were transmitting at 100 mW continuously, which probably isn't the case ever, you might increase the time to 9 hours. Or perhaps if you transfer data at full speed on Wi-Fi it will use that. But then the whole thing will probably use much more battery in any case lowered the real benefit of lower transmission power in ideal conditions to more like half an hour.

The extra consumption of using 100 mW transmission power on Wi-Fi is quite small in the worst case scenario of continuous full power usage. And while it may cause lowering of signal quality when further away from the router etc. Those might account to lower transfer rates and more usage elsewhere on longer bursts etc. All in all, you might as well be losing battery time with 10 mW change in addition to possible problems with Wi-Fi connection alltogether and likely lower transfer speeds unless you are close to the Wi-Fi router.

As of now with the Wi-Fi bug I am experiencing (using about 180 mA no matter if Wi-Fi is on or off after having used it even once - only to go back to normal with reboot) there is no way for me to test the real outcome of the settings. And at least for that bug, there is no effect for that setting.

TA-t3 | # 9 | 2009-12-10, 10:33 | Report

The wi-fi chip isn't transmitting continously, quite the opposite. It's not like it's transmitting just because you're connected. It makes no sense to do that kind of calculation.

That is with a normally functioning setup. However, the problem you have reported (that the wi-fi chip consumes lots of power after disconnect) is not normal behaviour and a very interesting possible cause of battery drain. If confirmed, it should be possible to fix by a firmware upgrade.

When that problem has been fixed I for one won't bother with dropping my TX power to 10mW. It makes no difference on the N800 (except making things worse in some cases), there's no reason it should be needed on a fully functional N900 either.

taril | # 10 | 2009-12-10, 10:46 | Report

cool, I used lots of nseries device, all has this setting.
I have been never thought N900 has this too! :-)