Battery (again) - quite confused :)
 

Hi,

I've had my N800 for a few days now, and so far I'm loving it. I've tinkered a bit, but not taken it 'over the top'.
However, one thing keeps confusing me. It's the battery life. I've had several "smartphones" and I've used them quite actively. Their battery life has been about a day, and after active use they've needed 'food' nightly. No problems.
Same goes with laptops; used them extensively, and after a good session they've needed 'feeding'.
So, laptops, a few hours or so. Smartphones, every day, two if not used a lot.

But what about the Internet Tablet..? Currently I seem to get somewhere in there in between (kind of like my hated O2 XDA Exec); I need to charge it pretty much one-and-a-half-time per day... Which in itself isn't much of a problem, except if you're "out and about" all day without a charger and you really want to use it.
Which is a bit of a shame as the reason for getting the N800 was that I wouldn't have to carry a bag around me; Just N800+Phone+BT Keyboard... If I need to stuff a charger into my pockets too I might as well take my bag, and thus my laptop.

Anyway, I guess what I really want to hear from you is your experiences about this; probably more psychological more than factual battery life times. :)

So what's your experiences and feelings about how the N800 and its battery life can be put into a 'normal' gadgeteer life..?! :) Thanks!

Re: Battery (again) - quite confused :)
 

• The N800 has very dynamic power saving features, which means that the actual battery drain can vary dramatically depending on what it's doing at any moment. For example, when just sitting there on the desk with the backlight it can last 9-10 days. On the other hand, when running the internet radio it'll be a noticable drain on the battery after maybe two hours. If you execute a program that just loops the CPU 100% then it'll drain the battery so fast you can see it.
  
• The battery meter tries to indicate this ambiguity: Right now, when I tap the battery meter it shows 'When inactive: 10 days. When in use: 7 hours'. Obviously it can never guess completely right, because there are just so many things you might do in the next hours that will completly change the original prediction.
  
• Wi-Fi can sometimes drain the battery in an unexpected way, but this isn't too common. For example, I have a wi-fi router which somehow prevents the N800 from going properly into wi-fi power savings mode. It'll half the battery charge in two hours. On the other hand, the wi-fi at work represents a very light load, I can keep my N800 on that wi-fi for probably 2-3 days without draining the battery. I also seem to see a correlation between the speed of the network and battery drain: The faster the network, the better. A low-latency network is also better (that's the time you seen when you 'ping' a remote address). I'm guessing this is because fast = the N800 can do the networking in quick bursts and then go directly into wi-fi power savings mode.
  
• Sometimes certain SD cards will drain the battery unexpectedly. This has been reported several times here on ITT. I have no such problems with any of the cards I own though.
  
• File system crawlers can sometimes be the cause of battery drain. I have twice had the N800 run out of juice over night. I disabled the built-in metalayer-crawler in my N800 and haven't had any reoccurances. I have no proof yet, but my gut feeling is that the crawler was the culprit.
  
• Another time a runaway process emptied my battery. Turned out it was because I had started a program in osso-xterm, and instead of quitting the program and exiting osso-xterm I just stopped osso-xterm with the 'x' in the corner. Not a good idea.. some experimenting showed that this would leave the program I had started as a runaway process.
  
• After the above trouble I now have a CPU monitor (I use load-applet-run) installed, so that I immediately notice if something's abusing my CPU at unexpected times.

Lastly, under normal use my N800 will last for days before I really need to charge it. But in practice I charge it a bit most days, because I can (and maybe I'll be using one of those no-good networks later, when a full battery is a good thing.)

Re: Battery (again) - quite confused :)
 

Thanks for that extensive reply! :cool:

I always like running CPU meters for the same reason as you do; I know if something is stressing the machine out. I've installed something that shows up in the control panel as "Statusbar Graph Control" - but it doesn't seem to run. I also installed load-applet-run from a .deb package (searched for it and found some info on this forum), but that doesn't run either. Maybe they're the same!? :) Anyone got any idea?

I also tried switching to my other WLAN, but the N800 didn't want to connect for some reason (Might look into this a bit deeper at some point).

What is this file-system-crawler that you mention? What does it do? How do I turn it off if I decide that I don't want it?

And I know about those pesky processes that run away; It tends to happen to me if I leave ruby consoles running and close the terminal window by mistake... :p (this is not on the N800)

Thanks again!

Re: Battery (again) - quite confused :)
 

Applets: This is indeed a bit obscure, why it's done this way I've no idea. But here's how. Go into the menu. Then:
tools->control panel->navigation->status bar, and enable your applet. Easy, eh? ;)

file system crawler: It's called metalayer-crawler, and it's apparent job is to find media files for you to play in the media player. I've had it disabled for a long time now and the media player still does what I want it to do so I see no point of the crawler at all. I'm still scratching my head at that.
How to disable:
You must have 'becomeroot' installed, so that you can be root. Then:

sudo gainroot
cd /usr/bin
mv metalayer-crawler metalayer-crawler.off

(or some other name, the point is that its startup script looks for the original name and won't try to start it if it doesn't find it).
Then reboot. (You could also do /etc/init.d/metalayer-crawler0 stop _before_ the above, presumably that would avoid the need for rebooting. But reboot is easy... NB: Note terminating '0' (null) in the init.d script name.)

Re: Battery (again) - quite confused :)
 

Excellent!! :) After enabling the applet I found out that a reboot was due anyway... and I disabled the metalayer crawler before that... charging now (as some process had made the battery drain). Sweet!

Oh, and I seem to have passed on the N8?0 disease to a friend of mine who simply couldn't resist my N800 :D :D
And I'm loving it more and more! :) :)

Re: Battery (again) - quite confused :)
 

the metalayer-crawler was causing battery drain on my n800 w/ Os2007.

why not just remove the metalayer-crawler package? (will first need to remove a multimedia package that depends on it). better than nasty sudo/root tricks that have the potential to break packages.