thorbo | # 1 | 2009-01-12, 18:18 | Report

Hello All,

I have done a little browsing on the forums, but can't find anything totally definitive. I have heard that on reboot there are quite a few processes which need to run, but why on earth does it use 30% of my battery every time I reboot?

I can understand that if it sprinted at 2 ghz for 30 seconds or something, but there is no single (or multiple) thing that I could do for 45 seconds that would use 30% of my battery life. And as I understand it, 400 MHz is still the max speed. Any light shed on this great mystery would be greatly appreciated.

Am I the only one that suffers this much battery usage on reboot?

Thanks. Thor

allnameswereout | # 2 | 2009-01-12, 18:23 | Report

Which Maemo version do you run?

During a boot tons of processes run hence in general rebooting costs a lot of resources, and is not something a user should do a lot. There are some ways to increase general performance, and making sure you do not have to reboot also helps a lot.

Have you turned things like Metacrawler off?

thorbo | # 3 | 2009-01-12, 18:34 | Report

Yes, the meta crawler is off, and the system is generally in good shape. I guess my question was more along the lines of "What can happen in 45 seconds" that can possibly use that many resources, and why can't I harness that power if I need it for something else? or when I am plugged in.

Oh, and I am running the latest Diablo.

Picklesworth | # 4 | 2009-01-12, 18:38 | Report

Or, in other words, how can that possibly happen within the laws of physics in our universe? :P

As I understand it, the battery metering is a bit off so after a reboot it just detects 30% less battery life than before while really the change isn't that significant.

lcuk | # 5 | 2009-01-12, 18:52 | Report

losing 30% each time, wow.

have you noticed any other effects, like clocks not being at the time you expect, a feeling of weightlessness?
maybe some sort of anal discomfort?

if so, it might be aliens.

2 reboots should not drain 50% of your battery, I would speculate that you are seeing the difference between reading the battery scale "whilst idle" and "whilst busy".

I'm not sure if it attempts to compensate, but its likely that calculation thats going askew.

BrentDC | # 6 | 2009-01-12, 19:45 | Report

Try this:

Check your battery level.
Reboot. Check level again.
Then, go into "Offline Mode" and "Lock Touchscreen and Keys".
Wait 30 minutes.

Is battery level closer to before the reboot or after?

thecubed | # 7 | 2009-01-12, 19:47 | Report

Interesting-- someone else with the symptoms of my poor OS2008 N800...

Upon reboot my N800 also looses most of its charge (battery low warning) yet it continues to keep powered on and working for the rest of the day with wifi and Canola2.

I don't believe this issue has anything to do with the startup process, I think this is more an issue of the power management controller's firmware. It appears as if it only remembers the battery calibration data while powered on (which may attest to the fact that I may have a dead internal clock battery).

Even after checking the battery with kcbatt and battery-status console tools, the battery is at 50% or lower-- yet it just keeps on going despite the warning of 'impending doom' every five minutes.

My suggestion: turn off low battery alerts and just keep working... It's not much of a solution, but since it happens so rarely for me (I haven't had to reboot my tablet for 4 months), I just disable the warning until I get home and am able to recharge the battery.

lcuk | # 8 | 2009-01-12, 19:47 | Report

just reboot and wait for a while for the dust to settle.
changing settings and faffing wont give you the reason.

Matan | # 9 | 2009-01-12, 19:52 | Report

Reboot does not take 30% of the battery, since that would require the tablet to draw much more current than the system can actually stand. The system at maximum cannot draw more than something like 3W, and since the battery has about 5Wh, it takes about half an hour (at full draw) to waste 30%.

I saw a similar effect many times - battery appears half full, or even
3/4 bars, then I reboot and it has one bar, or none at all.

What I suspect happens is this: Estimating battery charge by voltage is not very accurate, as it depends on temperature and current draw, among other factors. Since Nokia don't want the values the tablet display to jump all the time (like reporting there are 7 days of standby and then after a few minutes
of use but no charge reporting 9 days), they don't display the raw value read from hardware, but apply some smoothing algorithm, which obviously depends on past readings. After a reboot there are no past readings. so the same (or similar) readings from hardware translate to different values reported to the user.

BrentDC | # 10 | 2009-01-12, 20:07 | Report

Is it possible to read the raw battery level (direct from the hardware)?

I'm thinking of an application that reads battery level every minute and adds it to a max 120 line log in /tmp/. The application then weights the readings slightly more toward present, to compute a more accurate reading (that would survive a reboot).

Possible?

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Last edited by BrentDC; 2009-01-12 at 20:09.