FIRST OF ALL, did you read all of my P900 notes?
I also wrote another page about batteries.
An user told me about a "quick discharge problem". The P900, after a full charge, discharges in about 5-6 hours without any reason (no phone calls and no weird operations) and the phone and battery also get hot. This problem began some time after knocking hard the P900; also, there was a program called "main" running, which couldn't be killed. Is it a software or hardware problem? Below, a small note that I sent him to help to understand what could be happened...
The "quick discharge" was some years ago a common problem for old cheap Nokia phones: after some 15-20 months of usage, even buying a high-capacity battery (1000mAh or so), the phone needed to be charged at least once a day. Some Nokia-related people said that some circuitry, when getting "old" (?), had a "boost of Ohm-resistance" (???), and similar excuses - in my opinion they were stupid excuses, but I cannot deny that there could exist a hardware problem that does actually not depend by the battery.
For your "P900 sudden discharge" problem, I try to show some hypotesis.
First: a software problem. Some auto-starting program (like SMan) could
use 100% of available CPU time (because of software bugs). This will
drain battery quickly but will be evident because of the system slowdown.
Reformatting the disk will wipe it (a "master reset" from the "secret menu"
should be better; look here for a full P900 reformat).
Note: yes, in this case you will see the phone hot: the battery drains quickly because the software does never leave the processor in "idle" (low-power consumption) mode. I happen to feel the P900 a bit more hot than normal after playing 80-100 minutes of MP3 files and/or transferring data via infrared port (while in the gunnysack, the P900 does have a good refrigeration).
I have always infrared and bluetooth enabled (but I don't use the SMan's continuous bluetooth-scanning features), and in my area GPRS/GSM signal do not drop too often (anyways, to save some battery, I use "GSM only": when the notebook uses bluetooth to ask for a GPRS connection, the P900 re-enables it only for the time of the data call). This way, and using often the P900 PDA-features (jotter, mail, etc) and phone calls (GPRS data and voice), makes me in need to put it to charge almost every night.
Note: if it's a software problem, you will see a quick-discharge (in a few hours) even if you keep it in "flight mode" with (apparently) no programs running and no phone and bluetooth activity. By default, the only application we see running after a boot is "Messages" application (pre-loaded in memory by the Symbian operating system for speed and convenience reasons). It can be stopped without pain, as any other UIQ-application, using task-managing functions of the SMan. Immediately after booting, if I start SMan and select "show hidden tasks", I can see these tasks running: Flipkeypad, EikSrvBack..., Applications, Beamer, Messages, Appicker. Free memory is always about 6500 kbytes at boot (but I'm using the Freetype DLL to use a .TTF font for the system menus and applications; if you don't use them, then you will see some more memory; if you use other third-party drivers, you will see less memory).
I found no "main" Symbian-executable (.EXE) or UIQ-application (.APP)
or dynamically-linked-libraries (.DLL) in my "C:" disk drive (internal
P900 drive). Maybe your "main" is from some other third-party software
(for example, a keytap driver, a TTF font manager, etc).
Please note: a software or firmware problem cannot be triggered by knocking the P900 or leaving it falling on the floor.
Well, if it's not a firmware/software problem, let's go on, and let's assume the P900 was actually hurted.
Second: a firmware problem. Some buggy programs could overwrite
some firmware area (yes, it can be actually done, and that's how the
firmware-upgrading runs). Upgrading the firmware will solve it.
Note: when I had my P900 blocked by a weird SIM-related error (it wasn't anymore able to read any SIM-card, thus it couldn't boot), I wasn't able to upgrade the firmware by myself, so I had it serviced. I am convinced (maybe I'm wrong) that service centers can actually do a "harder" firmware-update than our SEUS (Sony Ericsson Update Service) internet standard procedure.
Third, a battery problem. Maybe its "usage/percentage counter" is broken (or, simply, some battery element is damaged). This can be verified with another battery (even a P800 one, which is 1000mAh instead of 1260mAh, but will surely last for more than 6 hours). Yes, this kind of problem can be triggered by a hard knock on the P900, even though it's actually very rare (and very expensive to get repaired).
Note: a quick discharge in extreme environment conditions is almost normal. This kind of batteries discharges even if not used, when environment temperature is below 5-10 degrees or higher than 30-35 degrees (discharge is faster on extreme temperatures). On a hot day, while in train (without air-conditioning), I had a battery almost totally discharged in 10 hours (without phone calls and with minimal use), mainly because of continuous GPRS-retraining and environment temperature.
Fourth, a P900 hardware battery sensor problem: the sensor detects a fraction of the actual battery level, and says "battery low" when it's not that low. This could be verified using a common electricity "tester"; use a small 5 volts lamp and test it on the battery only, first when the P900 says "98%" or more, and then when it says "0%" (do test amps and volts: use a tester to verify how much milliampere the lamp is consuming and what voltage does it have; and remember that the battery voltage when not connected to anything may give out unreal highly-optimistic results). If the tester says the battery is OK, then the P900 hardware battery sensor is damaged (this could be quite hard and expensive to get repaired). I don't think this problem could be triggered by a hard knock on the P900.
Note: a "software" battery sensor problem (system routines overwritten or some firmware table missing or damaged) is actually a firmware problem, and falls below the second case examined before (i.e., it was not a hardware problem).
Fifth, some other P900 hardware problem. If everything was tested and OK, then there is some other P900 hardware problem (maybe some short-circuit on the P900 motherboard, or on the LCD controlling circuits, or a damaged resistor, because of a hard knock on the P900), and it has to be serviced (this also is pricey).
Since November 2003, so far I charged/discharged my P900 at least 300-400 times, and in the last months it is showing some first signs of aging (a little longer charging time, almost every night needs charging because current is below 5% full, quickly drops from 99% to 80-85% with only a few minutes phone talk or MP3 playing, etc) but I am still happy with it.
Sony Ericsson P900 index - send e-mail - home page