I hate having to depend on batteries, and thinking perhaps that in the future the useful life of my N900 will be limited by the life and availability of battery replacements.

One of the awesome qualities of machines like the Zaurus SL-C1000 is that you could use it without a battery when the OS allowed for it. The only limitation in that case was that you couldn't use the CF slot, but useability was not reduced substantially.

I think what causes this issue with the N900 is bme, isn't it? And I just saw Pali mention in the KP 52 thread that a replacement to bme will take place in the near future.

Isn't it possible, from the point of view of the hardware, to run an N900 without a battery, simply with the USB charger connected?

It takes for a depleted battery around 3 hours to be fully charged, and I can't think of a single instance where I have run down a battery in less than 3 hours, so the USB port could theoretically supply enough juice even in peak draw conditions.

Or is there some other hardware limitation? As in, perhaps it is impossible to derive electricity directly from the USB connector to the mainboard without the intervention of the battery. How would it be possible then to swap batteries with the USB charger connected? I've seen it done, but I suppose there could also be a capacitor or something else, although I doubt it.

It would be really good to have this capability to future proof the N900.