I can check it on mine, i just connect a multimeter to the 2mm plug and then i can monitor the voltage directly from the battery in real time

But again i don't have a working USB and cant find a shop/repair shop where i can take it directly to.
I don't want to be apart from my N900 because it does so much and it's not fun to use my N95 after having the N900.
I want to take my N900 in the shop pre-dissembled so that they can just solder the FUSE out and a new one in, this way im only "offline" for 30min MAX

In my case im going to use a quote from 'small soilders'
-- The N900, everything else ... is just a toy.