loosing battery power big time when using wifi

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loosing battery power big time when using wifi

Postby Getafix on Fri Mar 01, 2013 2:03 pm

I get decent power from a full charged battery without wifi. But when wifi is turned ON and connected to internet my battery drains like anything. It goes to 10 % in 20 minutes time.

Laptop runs Linux Mint 14 with Cinnamon desktop, nvidia graphics driver (via nvidia-current) and ath9k wifi drivers.

getafix@mintbox ~ $ sudo lsmod | grep -i ath
[sudo] password for getafix:
ath9k 116549 0
mac80211 461161 1 ath9k
ath9k_common 13783 1 ath9k
ath9k_hw 376155 2 ath9k,ath9k_common
ath 19187 3 ath9k,ath9k_common,ath9k_hw
cfg80211 175375 3 ath9k,mac80211,ath
getafix@mintbox ~ $

Wifi device details follow.

getafix@mintbox ~ $ lspci -vvv | grep -A 10 Wireless
02:00.0 Network controller: Atheros Communications Inc. AR9285 Wireless Network Adapter (PCI-Express) (rev 01)
Subsystem: Foxconn International, Inc. T77H126.00 802.11bgn Wireless Half-size Mini PCIe Card
Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx-
Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
Latency: 0, Cache Line Size: 64 bytes
Interrupt: pin A routed to IRQ 16
Region 0: Memory at e7a00000 (64-bit, non-prefetchable) [size=64K]
Capabilities: <access denied>
Kernel driver in use: ath9k
Kernel modules: ath9k
getafix@mintbox ~ $

Kernel: 3.5.0-17-generic

Can anyone lend a helping hand? Thanks.
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Re: loosing battery power big time when using wifi

Postby Getafix on Sat Mar 02, 2013 2:32 am

I think this post is in the right section of forum. Wonder why there is no reply. If I haven't provided enough details just let me know. Any proven tweaks to reduce wifi power usage?
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Re: loosing battery power big time when using wifi

Postby Michael42 on Sat Mar 02, 2013 3:01 am

It looks obvious that your wifi card is transmitting at max power.

There may be a way to set the adapter's config to lower it, but I haven't seen of a way to do it. I don't use wireless networking myself, but this interests me too. And, I've seen a few other users around here complaining about the very same problem you are having.

You might try searching from the main forums for terms like: wifi power config wireless battery...etc. combinations of those. You can try googling for linux wireless driver power config, etc... See if you can come up with something.

In the meantime, post your
Code: Select all
iwconfig

and maybe we'll find a starting spot.
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Re: loosing battery power big time when using wifi

Postby bigj231 on Mon Mar 04, 2013 3:30 pm

I seem to recall there being a way to reduce the transmitter power with iwconfig. I haven't had to do it for a while, but I believe there is an auto setting. Try turning power management on with iwconfig. I can get about 3 and a half hours with WiFi on and a decent signal. They lowest I've seen is 2 hours with constant video streaming. I get about 4 hours with WiFi off though.
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Powertop output

Postby Getafix on Mon Mar 11, 2013 12:11 pm

Power Management is on when on battery.

I was looking at the powertop output at these times. I found some useless drivers loaded which had to be blacklisted. I followed this doc. http://wiki.debian.org/KernelModuleBlacklisting

Must be noted that some modules when blacklisted may not take effect and can be loaded back. ldd command can help to find its dependant modules and in which case they need to be blacklisted as well. But that has not helped here.

Here is the iwconfig output as asked for.

@mintbox ~ $ iwconfig
wlan0 IEEE 802.11bgn ESSID:"phoenix"
Mode:Managed Frequency:2.412 GHz Access Point: E8:40:F2:1D:5E:73
Bit Rate=65 Mb/s Tx-Power=14 dBm
Retry long limit:7 RTS thr:off Fragment thr:off
Power Management:on
Link Quality=65/70 Signal level=-45 dBm
Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0
Tx excessive retries:4 Invalid misc:168 Missed beacon:0

lo no wireless extensions.
@mintbox ~ $

The tunables option in powertop has toggle control to change values but the changes don't take effect after a reboot. Can anyone tell me how to make it permanent?
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Re: loosing battery power big time when using wifi

Postby Michael42 on Mon Mar 11, 2013 3:50 pm

I was looking for the Power Management to be On, and it is. Everything looks like it should, and I'm not sure if 14dBm is max power, so my experience stops here.

I did see another post in this forum where you can
Code: Select all
sudo apt-get install laptop-mode-tools


Possibly it could be of help to you. The post is here, and it is another one saying Laptop battery power is way lower after installing Mint :
http://forum.linuxmint.com/viewtopic.php?f=49&t=127908

Maybe it will be of help with your other question as well. Let us know if it helps or not.
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Re: loosing battery power big time when using wifi

Postby bigj231 on Mon Mar 11, 2013 3:53 pm

If the powertop command actually helps, you could write a script and have it execute on startup. Or if it's just a few lines, add it to your rc.local.
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Re: loosing battery power big time when using wifi

Postby Getafix on Thu Mar 14, 2013 11:23 am

Great thanks bigj231.

Michael42, do you think laptop mode tools can help in 3.2 kernel?
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