[Touch Viva, MDA Basic ROM Development] pajerm:
This is only an copy and past of an useful article found on this page:

http://www.techparaiso.com/windows-...our-windows-phone-network-backlight-a-general

1. Power Management Tweaks

So upon my year long experience with building Windows Phone Roms, i have come across all these Power Management tweaks that would someway or the other improve your Device's Battery Life. Although i found these from alot of sources but even if someone knows some more then kindly add to it.

[HKEY_LOCAL_MACHINE\Software\Microsoft\Bluetooth\AudioGateway]

"PowerSave"=dword:00000000

[HKEY_LOCAL_MACHINE\Services\BTAGSVC]

"PowerSave"=dword:00000000

[HKEY_LOCAL_MACHINE\Comm\AsyncMac1\Parms]

“DisablePowerManagement”=dword:0

[HKEY_LOCAL_MACHINE\System\StorageManager\FATFS]

"EnableCache"=dword:00000000

[HKEY_LOCAL_MACHINE\System\StorageManager\Filters\fsreplxfilt]

"ReplStoreCacheSize"=dword:00000000

[HKEY_LOCAL_MACHINE\Drivers\SDCARD\ClientDrivers\Class\NAND_Class]

"DisablePowerManagement"=dword:00000000

[HKEY_LOCAL_MACHINE\Drivers\SDCARD\ClientDrivers\Class\MMC_Class]

"DisablePowerManagement"=dword:00000000

[HKEY_LOCAL_MACHINE\Drivers\SDCARD\ClientDrivers\Class\SIM_Class]

"DisablePowerManagement"=dword:00000000

[HKEY_LOCAL_MACHINE\Comm\PPTP1\Parms]

"DisablePowerManagement"=dword:00000000

[HKEY_LOCAL_MACHINE\Comm\L2TP1\Parms]

"DisablePowerManagement"=dword:00000000

[HKEY_LOCAL_MACHINE\Comm\ConnMgr\Planner\Settings]

"CacheTime"=dword:0000003C

"SuspendResume"=hex(7):\

47,50,52,53,5F,62,79,65,5F,69,66,5F,64,65,76,69,63,65,5F,6F,66,66,00,00

2. Disable Auto Network Search

Another thing that eats up the battery is the Enabled Auto Network Search mode or 3G Network Mode. Being on a 3G Network or constantly looking for Network alternatives does require the Device to work and eat up battery. So the below tweak is to set the Network to GSM only, but if you want 3G then you can anytime go to settings and change it back to 3G. Either by going to Setting/System/Phone and disabling Auto from there or add these below Registries.

[HKEY_LOCAL_MACHINE\Software\OEM\PhoneSetting]

"Last_SMS_Tick"=dword:00000000

"ShowPDPPage"=dword:00000001

"RefreshPINStatus"=dword:00000001

"EnableAutoPickupSec"=dword:00000001

"ShowNITZPage"=dword:00000001

"ShowUMTSBandPage"=dword:00000001

"ShowPINPage"=dword:00000001

"PhoneSettingExt-DLL"="PhoneAdvanced.dll"

"ONSDisplayRule"=dword:00000001

"QOSTrafficClass"=dword:00000004

"LongNamePrefix"="3G"

"Enable3GLongNamePrefix"=dword:00000001

"UnattendedModeTimer"=dword:00001F40

"ShowALSPage"=dword:00000001

[HKEY_LOCAL_MACHINE\Software\OEM\PhoneSetting\BandType]

"ItemValue4"=dword:00000003

"ItemName4"="UMTS(2100+800)"

"ItemValue3"=dword:00000002

"ItemName3"="GSM(1900+850)+UMTS(1900+850)"

"ItemValue2"=dword:00000001

"ItemName2"="GSM(900+1800)+UMTS(900+2100)"

"ItemValue1"=dword:00000000

"ItemName1"="Auto"

"ItemCount"=dword:00000004

[HKEY_LOCAL_MACHINE\Software\OEM\PhoneSetting\NetworkType]

"ItemValue3"=dword:00000002

"ItemName3"="WCDMA"

"ItemValue2"=dword:00000001

"ItemName2"="GSM"

"ItemValue1"=dword:00000000

"ItemName1"="Auto"

"ItemCount"=dword:00000003

[HKEY_LOCAL_MACHINE\Software\OEM\UMTS]

"OpMode"=dword:00000001

3. Backlight Settings

Third Important Tweak is the Backlight Settings. The interval in which the Backlight Turns off Automatically, the Dimness of the Back light, etc.

[HKEY_CURRENT_USER\ControlPanel\BackLight

"Brightness"=dword:00000002 ; Brightness Level Set to 2 on Battery Power

"ACBrightness"=dword:00000002 ; Brightness Level Set to 2 on AC Power

"BatteryTimeout"=dword:0000001E ; Turns off Backlight(Dim) if device unused for 30seconds on Battery Power

"ACTimeout"=dword:0000003C ; Turns off Backlight(Dim) if device unused for 30seconds on AC Power

[HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Power\Timeouts]

"ACSuspendTimeout"=dword:0000012C ; Turns off device(Sleep) if unused for 5minutes on AC Power

"ACSuspendTimeoutSave"=dword:0000012C

"BattSuspendTimeout"=dword:0000003C ; Turns off device(Sleep) if unused for 5minutes on Battery Power

"BattSuspendTimeoutSave"=dword:0000003C

Although the AC Power tweaks are not relevant for Battery Life but just included.

Now as the Tweaks mentioned above are Constant for everyone so I've made a Installation File of it to straight away install it to your Devices. Download the file below and install to any device and just restart the Device.