The most systematic analysis of Lumia 800 battery ...

Hi, don’t mean to be arrogant, but I’ve read many threads, forums, posts etc.  There are tons of info, someone tried a table, etc. but no one has attempted to summarise the relevant parameters.  So here goes:
1.     I have a Cyan 800, bought locked at “3” UK, then unlocked.  It’s beautiful and makes iApple UI look, well, jurassic or geriatric in comparison.  The screen is so beautiful that I switched the thing on just to marvel at the ease of reading the glorious white on black (real black, not grey) and I am smitten by the ascetic aesthetics of the UI that put function over form (I simply can't stomach the saccharine animation of Apple, it is an eye candy for a while, then becomes bothersome, at least to me.
2.     Initially, I noticed that the battery life was not great, but it did not seem disastrous, and I read all the gleeful Apple worshipping media trying to fan the battery issue, but I thought that it was a storm in a tea cup and just the usual attempt to put-down any competition to Apple.
3.     Until a couple of days ago I noticed that I have less than ½ charge after only a few hours off the charger without really doing almost anything.
4.     I panicked, read as much I could the forums, etc. (including probably the most technical – XDA-Forums) but got there only one real advice, the “diagnostics” mode (dial ##634# - I also downloaded an App (called Diagnostics) that does bring you straight to the relevant page without the need to “dial” the ##634#).
5.     I then tried to see what was draining the battery, I stopped 3G connection and “presto”, the drainage stopped and I thought that I resolved the problem (at least for me, there were clearly problems with a certain hardware code, see below).
6.     For one day, the battery was very durable.  Even though I had some reasonable With-Fi browsing and calls (GSM, not 3G), there was more than a 1/3rd of the battery left after about 20 hours of the last charge.
7.     Then, today, the morning began very well (in terms of the battery), it was losing less than a few percentage points every hour.  I used it for light browsing and a bit of Bluetooth listening.  Them my 7-yr old played some X-Box games for a bit, but the battery was way above 2/3rds.  I then noticed that the phone was warm even though it was not on.  Initially, I thought that it was warm because it was on my body, but then I noticed very fast fall in the battery level.  Check:
a.      the 3G again, no it is still off
b.     wi-fi and Bluetooth off
c.      I even checked what Apps were in the background (though I know that it is NOT draining)
d.      - nothing helps, the drainage was high, even when the phone was closed (i.e., not used).
8.     There was nothing I could do, until I shut the phone down completely and switched it on again.  Then, the drainage returned to the “good” level, i.e., a few percentage points per hour.
9.     So bottom line, I think that there was something going-on “in the background (that is why the device was warm even when closed) – the problem is that this seems to be intermittent/random and very difficult to put the finger on what causes this problem.  I hope that Nokia resolves this problem and not only the “low” battery capacity (see below) that Nokia acknowledged.
So after this long intro, what do I see as the “hard-points” here? The most important parameters for the story seem to be in the following screens:
1.     “Diagnostics” (##634#) “Battery Status” screen;
2.     “Settings”/”Systems”/”about” screen, have to press the “more information” button;
3.     “Settings”/”Systems”/”battery saver” screen;
4.     The battery icon and its remaining capacity representation on the main screen.
The “Diagnostics” (##634#) “Battery Status” screen:
 It seems to contain the following info:
·       “Charged” – seems to display ALWAYS the figure “65535%”;
·       “Voltage” – seems to show figures of between 3.700 V (i.e., volts) to 4.1 or 4.2 volts
·       “Current”, followed by “charging” or “discharging” and the current, usually between 130 mA (i.e., milliamp) and 500 mA.
·       “Full Charge Capacity” – showing different figures for different people, usually between slightly above 900 mAh (i.e., milli-Amper-hours) and slightly above 1,500 mAh.  Although in this should logically be a fixed-for-ever, or at least in the short term level, the figure seems to fluctuate slightly, see below for more detail.
·       “Remaining Charge Capacity” – clearly the most important parameter, showing the remaining mAh in the battery.  Although in theory, the level immediately after long charge should be equal or very near the “Full Charge Capacity”, in practice, it almost never is (remember, I take this not only from my case, but also from numerous reports that I got from the various forums), see below for more detail.    
The “Settings”/”Systems”/”about” screen, the relevant info items:
·       OS version – it seems that the latest one (as of late dec 2011) should include “7740” in it.  apparently, Nokia promised some respite from the battery bugs in this “7740” update, but from what I read in the forums, there was absolutely no difference.
·       Firmware revision number – interestingly, the firmware revision number includes “7720”, though I am not sure what it means.
·       Hardware revision number – this ends up with “xxx.3” or “xxx.4” – as below, I wonder if this is a different OEM factories designation, but it seems to me that it is the “xxx.4” that has one type of problem (low “Full Charge Capacity” of under 1,000 mAh).
The “Settings”/”Systems”/”battery saver” screen – what is relevant for us is under the “battery information” – you must unplug the phone from charger to see three lines:
·       “Remaining battery life”: supposed to be between 0 and 100% of course (though in this context, calling it “remaining battery life” is misleading, or at least inconsistent with the “remaining charge capacity” of “Battery Status” screen.  Perhaps it would be better to call this “remaining charge”
·       “Estimated time remaining” – measured in hours, in my case, it is always under 15 houts.  There is no explanation what it means, I would guess that this is “how many hours will your phone work in stand-by mode”, but then it is way way below what Nokia said – measured in hundreds of hours.
·       “Time since last charge – measured in hours.
So below I summarise my findings, but first, my unit parameters:
Color: Cyan (does not seem to make any difference to people out there – problems “cross” colours;
OS: “7.10.7740.16”
Firmware: 1600.2475.7720.11414
Hardware: 112.1402.2.3
So, in MY case:
1.     “Battery Status” screen:
·       “Charged” – seems to ALWAYS display the figure “65535%”, like all others on the forums.  This must be some kind of mistake because it does not change or update and makes no sense, now that we are in this so deep, I hope that Nokia explains what the hell this means, if at all;
·       “Voltage” – seems to show figures of between 3.700 V (i.e., volts) to 4.1 or 4.2 volts.  When the battery is low, the voltage seems also to fall below 4.0;
·       “Current”, followed by “charging” or “discharging” and the current, usually between 130 mA (i.e., milliamp) and 500 mA.  When the battery “plays nice”, i.e., there is no “problem”, this figure is under 150 ma, usually going seesaw between 140 and 155.  When 3G is on, it is above 250 towards 270 mA
·       “Full Charge Capacity” – showing for me usually above 1,500, constantly changes, though less frequently then other figures in this screen.  Strangely I noticed that when it is cold (I was jogging and it was in an external pocket with about 7C outside), this number went lower, under 1,500.  Perhaps the battery when colder can hold less charge?  Nokia should explain.  I think that in case of Hadware versions that end in “x.4” the maximum in this parameter is reported under 1,000.
·       “Remaining Charge Capacity” – in my unit this never reaches the “Full Charge Capacity” (which is usually slightly above 1,500 mAh), it stops below 1,350 mAh.     
2.     “Battery Saver Screen” and the battery icon on the main screen:
In my case, because the “Remaining” charge never reaches close to the “Full Charge”, when I disconnect the phone from charger, I get straight that “Remaining Battery Life” is “94%” (1350/1500 or so) – and the icon is never 100% “full”, rather “almost” full.  “Estimated time remaining” never really above 15 hrs.
So, there seem to be (at least) two major issues/problems in relation to battery/working-time:
1.     Firmware revision (probably) “x.4” may have a faulty battery that would not charge above 1,000 mAh (950 mAh is mentioned by many, or about 1/3rd less than intended by Nokia (unless it is a software bug, which will be huge relief for all, especially for nokia);
2.     Firmware revision “x.3” may have escaped the “crippled” battery of revision “x.4” guys, but from time to time it can lose battery charge at least 2 times faster than otherwise, most likely due to some background processes that can be felt as the device becomes warm even when not switched on (i.e., in stand-by mode).  This seems to be intermittent or random and can be stopped by powering-down the phone and then powering-up again.
3.     In all cases, the claim that the phone can be several days in sand-by mode, must be wrong and Nokia must address and explain this.
So in summary, at least in respect of battery, there is a mess.  Will be interesting if some people with other WP7 devices can chip-in and say whether it is similar in their cases, but Nokia should be open and explain and even admit mistakes, I hope that this can be rectified by software, or at least it is not a “terminal” complication for Lumia 800, which is a beautiful device.

I would like to thank all the people here who have taken the time to put all this info together for us all and hope it is of help to the folks who are having trouble with battery life. I'm not doing to bad on battery life myself as it always last me though the working part of the day when I don’t have access to a charger and I will soon be updating my car cradle to take the Lumia so will have access to a charger though the day to. Personally I have come from the N900 and that phone also had some battery issues when it first came out which where pretty much sorted over time, as for manufactures claims on battery life, I always read these figures the same way I would read expected miles per gallon that car manufactures put out, meaning that there would only be a very select few that would ever get what the manufactures say you can get the rest of us will all get a very wide variation on these figures. I know that Nokia have acknowledged that there is an issue with battery life and not all of us have this issue, at this moment in time I'm not to unhappy with the battery life, but if it improves then I will be pleased. From all the posts I have read on this site it does seem that some people do read manufactures specifications as if there are set in stone, I'm not criticizing anyone here would just like to say that they are trying to sell you something so have a good look at the figures and maybe check them with other independent sources if at all possible. My only disappointment really is that we have to rely on other people and not Nokia themselves to let us know what’s going on, I wish the manufacture would be more open and quicker to let us know what’s going on and what they are doing to sort out problems and some sort of time frame that we could expect something to come out to fix a problem. I know bugs can me very difficult to find and ever more difficult to fix sometimes but if Nokia put out a weekly report about how things where going on bug fixes or forth coming updates it would help everyone in deciding where they are going with their chosen product.
Again many thanks to all the people helping us all out and wish you all a happy bug free new year.