[HD2 Windows Phone 7 Development] zcdg:
After a lot of playing with T-Mobile US HD2 WP7 i found one interesting thing:

If i start camera with green button and then switch to video mode there, wait for autofocus and after that just simple go out to main screen by pressing windows(middle) or back button then standby Battery Current drops to -5-6 ma from regular -40-42 ma(minus means discharge). (Switching to video is important - if not switched no results found)

It stays -5-6 ma on standby until next reboot. If i reboot and don't do this camera play current is -40-42 ma. But if i start camera -> switch to video -> out - Battery Current -5-6 ma. To measure use Battery Tool.

After hack/trick applied I used phone in different ways - talk internet email - standby still low 5-6 ma. I gave it 12 hours try - lost only about 12-13 % of charge. Checked battery outside of phone with load - real lose of charge was about same as Battery tool shows. Will continue to test longer but can expect at least few days with some usage of phone. Did the same trick with my friend's phone - same results. It looks like really a bug some where.

This problem really exist and found in all ROMs.(a little difference between TMOUS and EU HD2)

Aug 30, 2011

FOR this trick to work on any ROM versions(including all Mangos) software WP7 radio must be lower then 5.62, so only from 5.51 to 5.61 works. Recommend to use 5.51 or 5.51T soft radio and trick will work all the time.

History Update:

As of Apr 29, 2011: Confirmed to work for most people. This has to be done ONCE ONLY if you reboot phone.

Confirmed one phone has low standby current 3-7 ma after reboot without this hack - but model of phone is ORIGINAL HD2, not T-Mobile US. ROM is HD2O 1.04.

One T-mobile US shows low standby at bootup. XBmod 1.04.

If your phone shows 3-9 ma standby after reboot without this trick - then this not for you. Your phone has good standby already.

Real battery life vary from about 4 hours(continues usage of cell data and browsing) to 4-5 full days (standby only no usage at all-just few short calls, location on, data on, bluetooth on, xbox off, wifi off).

May 17

Update:

Tested HD2O 1.12 nodo - trick works perfectly right away getting 3-5ma!!! After a day of use(not much use) - battery life is amazing!!!

Tested original NODO(YukiXDA) one more time(total two times flashed this rom to be sure) - couldn't get stable low standby - unpredictable, most of the time 40-42ma sometimes even higher. Tried so many times. I don't know why results are not so good. Update: Yuki original ROM used different WP7 Radio - 5.66 - which is not working with trick on TMOUS HD2. For trick to work TMOUS must have 5.51 or 5.51T Radio.

May 18

Tested XBmod 1.10 nodo - trick works perfectly right away getting 3-5ma!!!

June 02

Continue using of HD2O 1.12 - battery life is amazing!!!(T-Mobile US HD2) Didn't have any single stability problem for 2 weeks!!! Speaker volume can be adjusted with registry hack.

Jun 07

Update: Yuki original ROM used different WP7 Radio - 5.66 - which is not working with trick on Eu and TMOUS HD2. For trick to work for 100% in 2G and 3G, ALL HD2 must have 5.51(original DFT) or 5.51T(from Ansar) Radio(part00.bin).

From my experiments 5.51T looks a little better than 5.51 overall(not sure 100%). There is no any benefit for me of use 5.66 Radio. Just use any WP7 ROM(even Yuki's ones) and replace part00.bin for trick to work. It was TESTED on all Yuki's ROMs.

Jun 08

Yuki's v3 final works exactly the same for standby current - radio 5.66 in ROM trick doesn't work, if replaced with 5.51T - trick works as usual 3-9 ma in all modes

Jun 09

Tested HD20 1.14. Much better than Yuki's for me(TMOUS) - more stable, feels solid no stability problems at all. For the first time HD2O changed Radio to 5.66, so i had to change part00.bin back with 5.51T to have good standby - 3-7 ma in any mode 2G or 3G with the trick. HD2O 1.14 is the best ROM overall again! Overall best and battery life is amazing after radio changing!!!

Jun 17

YukiXDa made the best ROM now with V4 lang2. I have never had so good battery life before!!! I have used 5.51T(TMOUS) with trick.

Excellent work Yuki!!!

Jun 29

Yuki made even better - V5. I am able now to get to some registry enrties i need!!! Enerything is perfect for me, except too many shortcuts to all setup settings:).