Um wouldnt hibernation kind of defeat the whole point of this device being a phone as well as a tablet. I cant see myself ever wanting to miss phone calls etc.

power consumption in idle is near zero anyway...

well if you say that one can switch battery without hibernation & without reboot, we can close this thread right away.

Not from what I've read :P some blogs say that you can get a few days out of it in standby mode without GSM radio turned on! So... near 0 is far from correct if your phone dies 2 days after no radio usage and in idle-sleep mode.

Hibernation and most suggestions on lesswats.org aren't or are barely interesting on ARM and other mobile/embedded devices. You'd need to write all the data in RAM to swap, and read all that again when powering it up. That uses a lot time, and also resources/juice, while the ARM in idle mode barely uses juice. You might as well leave no application open instead, put all receivers and transmitters off, or only leave voice open for phone/SMS, or suspend an application which uses a lot of resources. When battery almost empty Symbian has option to disable cellular data. Alternatively, something like powertop or iotop or htop could help debug (in SDK or on real device). All these 3 run on Linux/ARM.

A battery pack is interesting. Theoretically one could have one which supports the Nokia charger, but also one which supports USB charging. The latter allows one to also use other devices to charge via USB. However, USB charging is slower than using the official Nokia charger.

You could even use USB on your laptop to charge your N900. Not sure that works when laptop is on suspend or hibernation mode (I doubt it, may depend on case-by-case, hardware guru can clarify hopefully). Why would you do that? Well because you're on the go and your laptop is not required right now whereas your phone is. Then better give juice to the phone then. Or you actually only use your laptop as battery for your N900. Or the reserve battery of your laptop. I think I've seen such 'mods' for iPhone. Problem with reserve batteries is to store them for longer time you need to have them not fully charged, instead 40%, and that doesn't yield much, although OTOH a laptop battery would. And it could be a life saver so to say.

[EDIT]When I was in train from Belgrade to Munich I had only one power source, and I had to switch my laptop and phone constantly (tethering drained the phone's battery). Had I been able to charge my phone on my laptop's USB I would not have to switch them whole time.[/EDIT]

ok so hibernation is totally off limits because it would be probably the same as shutting device down, switching battery and turning it on again.

I think that I'll order a holder 4xAA plus one 5v regulator and usb connector after someone confirms that the tablets stays on when plugged in and battery is removed or then i'll test it myself later when my n900 comes knocking to my door...

I like the look of the PortaPow USB battery, from £17.50. Anyone tried one?

http://www.portablepowersupplies.co....atterypack.htm

if you are going to extend it through portable charger, why not thinking about solar? Either you attach it to n900 or modifying the portable charger.

Also, check this out: http://www.instructables.com/id/DIY-...adio-for-%245/
If someone up to try this, try to link AAA batteries together (I am not sure about 5800/N900 battery size/space so probably this might or work. Anyway linking 4 of AAA's batteries with each 800mAh (you can find higher) this means 3200mAh.

Now for people who are interested to know the difference this will gave them , simply use the ratio to determine your extra running time.

Now if I remember n900 is having 9 hours as a call time (Forget this , unless you want to compare your gain to it) I will consider 6 hours in extreme using

(3200mAh/1350mAh)* 6 hours = 14 hours and 22 minutes in extreme using conditions
now for the talk time:
(3200mAh/1350mAh)* 9 hours = 21 hours and 20 minutes of continues talking

that reserve battery will do just fine, but device will reboot when you switch the battery. I think the HW itself supports the hibernate mode for some seconds, but it's not enabled. Time to start looking at omap3 docs and do some kernel hacking. (eh, for some of you, me, I'm just fine with the battery as it is)

I second external battery packs. Lots of them available already, as previous links point!

I wouldn't use AA batteries, but rechargeable AA cells instead... Think of the environment! Put 4 or 5 of them (4.8V or 6.0V - someone prove me wrong, please!) together, add expensive, top-quality regulator, USB cable, some casing and you're done. First I laughed at chargeable chargers - out lout - but if they pack enough power, they just might save your week...

How about solar cells? Limited use cases, but hey, free power! Also widely available...