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Posts: 29 | Thanked: 11 times | Joined on Oct 2007
#1
I was wondering if you guys also noticed booting from SD card significantly reduces the standby time?

Often my N800 shows an empty battery after just 48 hours, where it was mostly standby (locked) and only used for a few hours. I've also tested with wifi on and off, but it doesn't make much difference. Not booting from SD card seems to increase the battery life, but I'm not really sure.

Could it be that using the SD card instead of internal flash uses more power when the OS is doing stuff while in standby? (like checking RSS feeds, checking mail, etc)
 
Posts: 2,152 | Thanked: 1,490 times | Joined on Jan 2006 @ Czech Republic
#2
Originally Posted by whouweling View Post
Not booting from SD card seems to increase the battery life, but I'm not really sure.
With same set of installed apps (i.e. exact clone) and same usage pattern?

Originally Posted by whouweling View Post
Could it be that using the SD card instead of internal flash uses more power when the OS is doing stuff while in standby? (like checking RSS feeds, checking mail, etc)
Could be. But the difference is not big (if there is one). Internal flash needs power too (it is NAND memory just like inside SD card) and jffs2 filesystem is compressed so you may even burn more CPU power with internal flash than with SD card. It may depend also on card size and manufacturer, bigger SDHC cards are said to be power hungry.

I am booting from card with both 770 and N800 for quite long time and did not notice shorter battery life but it is really hard to measure.

Sadly there is no way to get active power consumption of the device in mA in software (like with other devices) so we are in a dark regarding power consumption of various parts inside the tablet.
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Posts: 3,401 | Thanked: 1,255 times | Joined on Nov 2005 @ London, UK
#3
Bug #2602 is tracking significantly reduced battery standby time in OS 2008 however it's not specific to booting fom SD. I'm booting from internal flash and I'm lucky if my battery lasts 48 hours while the device is idle with a WiFi connection.
 
Posts: 29 | Thanked: 11 times | Joined on Oct 2007
#4
Originally Posted by fanoush View Post
With same set of installed apps (i.e. exact clone) and same usage pattern?
Not the same applications, thats why I'm not 100% sure if that's the cause. I tried numerous methods tracking down what eats the battery, tracing process stats, fsck'ing the cards so the crawler doesn't get stuck, turning off everything that does auto updating, but I can't seem to find it.

Originally Posted by fanoush View Post
Could be. But the difference is not big (if there is one). Internal flash needs power too (it is NAND memory just like inside SD card) and jffs2 filesystem is compressed so you may even burn more CPU power with internal flash than with SD card. It may depend also on card size and manufacturer, bigger SDHC cards are said to be power hungry.
You have a point there, didn't thought about that. (jffs2 compression cycles) It -is- a SDHC card thoug.

Originally Posted by fanoush View Post
I am booting from card with both 770 and N800 for quite long time and did not notice shorter battery life but it is really hard to measure.

Sadly there is no way to get active power consumption of the device in mA in software (like with other devices) so we are in a dark regarding power consumption of various parts inside the tablet.
Originally Posted by Milhouse View Post
Bug #2602 is tracking significantly reduced battery standby time in OS 2008 however it's not specific to booting fom SD. I'm booting from internal flash and I'm lucky if my battery lasts 48 hours while the device is idle with a WiFi connection.
Thanks, I'll start tracking this bug :-)

Hmm, it does seem to happen more often (unexpected drained battery) under the latest OS2008 than under the N810 firmware and OS2007.

Last edited by whouweling; 2007-12-31 at 00:23.
 
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