using 2 battery is a good idea.

only if you are using the device full blown time without barely access to a plug, (like wifi for 8 hours a day). Simply because current lithium ion ages throughout its time and after 3 years of shelf life its capacity will drop dramatically.

However that's, "current" lithium ion, the future holds much promise for this chemistry.

Takes about 2.5 hours from low battery warning to full charge

I just got my 800 all seemed fine I charged it first thing for about two hours.Then I upgraded to 2008 played for it a couple hours battery was down to one hour left.Here is issue I turned it OFF then charged it and still at 8 hours says charging? Turned unit on says I have two hours of use? I can charge it up while turned OFF correct? any Ideas why 8 hours still not charged?
Does it matter if n800 is on or off while charging I had mine off first nite
from 9 pm till 5 am still sadi charging
thanks
trido

With the N800-provided 890mAh charger it takes about 2 hours or a bit more to charge from low level to full (I prefer to charge it way before it drops that low but a couple of months back I had some situations where it accidentally discharged overnight due to rogue applications). With some of the smaller Nokia phone-chargers (390mAh I think) it takes an hour or two more.

@trido:
It sounds like something happened with the unit's charging control. And yes, you can charge it while it's off, and while it's on, and you can use it while charging (although when running battery-intensive applications or streaming internet radio you'll see it charging for a very long time).

Try stopping the charging. Use it for a while then try again. If that doesn't fix it then it sounds like something happened to the device and it may need a repair. It could be OS2008 though, but as there aren't other reports.. well, it could be worth trying a reflash.

nokia batteries are excellent in performance, please guide me how can i come to know that it is original or not?
Thanks

i am wondering iif anyone else has noticed this same problem...
since i upgraded to OS 2008 on my n800, it seems to have VERY short battery life! its killing me... it used to be so good for a day or two of moderate use with 'sleep' mode when not in use.
any advice?

Turn off Wi-Fi and Bluetooth before sleeping it (eg. pick Offline mode). Make sure there aren't any CPU-hog apps left running. Flash apps/ads in a browser window can also be CPU hogs.

I fell asleep with my N800 fully charged streaming Internet music last night. The battery power was used up completely. I applied the N800 charger, and set my timer(s). My N800 took almost exactly 2 hours to charge to the point where it stated "Battery full". Hope this information proves useful. M5

I'm having the same problem as Trido was having. Yesterday I left it on the charger for about 5-6 hours at work. End of the day it still said it was charging, but I unplugged and the battery charger said full. Used it for about a 1/2 hour on the way home and then put it away for the night.

This morning it was totally off and wouldn't turn back on. I've had it on the charger at work since 9am this morning and it still says charging 7 hours later. I did try the suggestion of taking it off the charger using for a few minutes and then putting it back on the charger. Did that about an hour ago and it still shows charging.