Nice nickname, @codelad

nice indeed!

Your current draw problems are not related to faulty battery, thats for sure. Anyway, better battery always mean longer runtime, so if you want to buy new one, I recommend polarcell BL-5J. they're *better* than genuine Nokia ones - latest original Nokia's have 1400 mAh Q10 capacity, while Polarcell gets 1500+ mAh Q10.

As for relative capacity, people gets as much as 1700 mAh out of Polarcells, as opposed to 1500 at most from Nokias (in your case, where standby is non-existent, I would expect relative capacity to be Q10 equivalent). Personally, I use custom-made dual-cell 3000 mAh battery, which gives me ~3300 mAh relative capacity during my everyday usage cycle, after 2 years of using it.

If you're more interested in topic of N900's batteries, see this thread:
http://talk.maemo.org/showthread.php?t=65568

Some informations in 1st post are outdated (like, high capacity SCUD BL-5J is practically unavailable, but polarcells are exactly the same capacity, probably same cell manufacturer), but it's still great battery knowledge resource.

/Estel

Estel,

Thanks for the recommendation of the battery. I have three batteries for my N900. Well, one of them just died. So, now I only have two. I may be in the market for another one.

Estel: If the core C4 state issue is not likely to be caused by a faulty battery, I might put off getting a new battery till I resolve the issue.

I've read through some of the posts in the battery thread - thank you for summarising it nicely, all over again! Unfortunately, none of the recommended batteries are available where I live. There are "original" Nokia BL-5Js on sale on the local Ebay, but I've burnt my fingers with one already. Anyhow I shall eventually arrange to get a Polarcell, once I get the C4 issue out of the way.

Next up, I intend to check the flex connectors and give the internals a close inspection (not that I'm counting on finding anything dramatic, but still).

Ancelad, coderus: Thank you. As you will have guessed, it is from a background in coding, in what already fast feels like a past life!

Definitely not related.

No problem, I'm glad it helped! They're unavailable where I live too - had to import them from half a world away. But, to be honest, they're not available where anyone live, under that person lives in Asia/China The bright side of the situation is that importing them isn't as hard as it may sound, and it's barely more expensive (including shipping) than buying some local battery, while the latter isn't even worth half the price paid.

/Estel

Point taken :-). I'll get around to buying one, hopefully after I get this power drain problem out of the way.

Meanwhile, I have taken apart my N900 and inspected the flex contacts, and they look alright. I did discover (and fixed) an unrelated hardware problem. The miniscule magnet under the kickstand was missing, which caused the SD card to fail everytime the stand was engaged (made this connection thanks to several posts on this issue, here). Took a good couple of hours of filing and sanding a magnet to replace it. Works good now.

To verify the powertop/zzztop inconstencies, I flashed the device to stock firmware and ran three repetitions of powertop and zzztop, alternatively. As before, the results differ. I repeated the process after flashing again, and a fresh setup of CSSU-Thumb. Again, the results differ. Attaching the results from CSSU-Thumb here.

It took me about 10 minutes to fix my magnet problem. With scissors and a flexible magnetic sheet from the back of a fridge magnet Works for the SD card sensor but sadly not for the keyboard open sensor.

It has occurred to me that now that you are such a seasoned N900 opener and flasher, perhaps you could try one more time but focusing on the motherboard instead of the flex cables. There may be some dirt (or a salt bridge left over after a drop in the loo the previous owner forgot to tell you about) causing a short circuit that does not hinder normal operation but just happens to push some chip enable pin permanently up or some such. A very long shot, but you do not have much to lose.

Use a soft brush to clean the motherboard. Be careful not to rip any components off. I would probably even use isopropyl alcohol to aid the cleaning but caution is required. Make sure the board is completely dry before reconnecting the battery.

As a desperate measure, took your advise and cleaned up the circuitry inside (and with isopropyl alcohol, no less!). Went to the extent of removing the metal shielding cans and cleaning under it. And I'm afraid the battery issue remains just the same :-(. As a nice side effect, I did end up with a N900 with shiny clean innards, though.

At this point, I'm resigned to living with the issue. And it's quite manageable, with a spare battery and and external charger.

I'm still interested in getting to know why the powertop/zzztop results vary so much.

zzztop lies, for reasons unknown at the moment (bug? Wrong implementation?), no doubt about that.

/Estel