That indicator is more or less completely useless, in my experience. I have seen it go from full to out of power in 20 seconds. It seems to extrapolate from how much power you've been using recently to how much you have left. So, if you have been sitting idle, it estimates that you have enough to keep going at that rate, but if you are actually trying to use it for something, the estimate is irrelevant.

Ive been experiencing too a drain of the battery in my N800 running Diablo. But not before a couple of days ago. I have my N at my office from 10am to 8pm with the charger connected (and obviously charging). However, I was on my way back home last night and watching some vids downloaded with myTube (its a 45 minutes ride) and then stashed my N in my backpack until this morning when I tried to get my emails when I saw that the battery was all gone. (Ive watched vids before and even movies on mplayer and never had that battery problem)
Batterry-satus wont work in my N (incompatible).
One simple idea that crossed my mind was to uninstall fm radio, since I thought that even though no earphones are attached to the device the fm function in the N keeps working (correct me if I'm wrong) in case of an accidentally activation of the play button in the fm radio applet.
Just my 2 cents.

I am also experiencing this seemingly random battery drain. I thought I had a solution working...putting my N800 into SoftPowerOff when not on the charger. Unfortunately, after some moderate-heavy surfing yesterday and SPOff overnight I found my Nit OFF this morning and had to plug in the charger to boot up.

Applets running:

GPE Summary
IPStrength
OMWeather
Personal Launcher

Up to date Diablo cloned to internal SD.

I keep the N800 plugged in all day(at work) as I am using it to run Portable Apps (Ceedo) from the external SD slot.

I still don't understand how the battery can drain that much from being completly shutdown. The device isn't even on. It's completly off.

is the a big diff between softoff and just locking the device?

It's pretty configurable, but it's the same as locking the device and, maybe, depending on settings, going to offline mode.

Good, it's not just me. I've had dead batteries in the morning for no apparent reason (charge showed days of idle). It appears to be independent of being connected to wifi or not.

Modest was active checking a gmail imap account. IM was logged in to jabber, yahoo, and aim. Home applets: clock, internet search, omweather (0.20.6), speedcontacts. I usually leave a browser minimized sitting on google reader for advanced mobile devices (www.google.com/reader/i).

I'm on the latest OS version.

Frank

and where do one configure this?

/etc/mce/mce.ini

oh, crap, i was afraid of that