Why not consider using powered USB hub?

For me it means a second power adaptor or battery to carry which is less practical. What if I use the n800 power adaptor to feed both nit and the hub at the same time by modifying the plug on it to be two ended?

You could buy a Nokia CA-100 adapter. That would let you leave the N800's AC adapter at home and charge from the same powered USB hub that's powering your USB device(s).

It's worth noting that the Nokia 2mm charging spec allows for 5.2 - 11V (iirc) (and a current window), so your "5V" 2mm charger probably outputs something closer to 6-7V..

@sjgadsby, CA-100 adapter gave me a good idea that I did not know before. Seems like a good solution.

@shadowjk, sorry for my negligence but what I need to understand from your comment? Can you please open up for me what you said? I am puzzled.

I mean that even if the AC-8E is labeled "5V", its real output is usually more than 6v, which will be too high for many USB devices.

All nokia powersupplies with 2mm plug are allowed to vary between 5.2 and 10V, and all the ones I have are at around 6V.

Edit: But if you're planning to create a external power supply to charge your N8x0, please don't just look at "10V" above and think you can feed it directly. At 5.2V the powersupply must have a current limit of about 1000mA, iirc, and at 10V this is closer to a 100mA limit...