It's basically common knowledge, check http://www.batteryuniversity.com/ and Wikipedia, among others, for more info.

Li-ion batteries have a shelf life (if you don't charge/discharge them at all) of about 2 years, depending on the charge state (50% or so is best) and temperature (cooler is better) or a cycle life of typically 300 full discharges' worth, depending on depth of discharge (really deep discharges are much worse, shallow to moderate are similar). So typical service life is a little over a year, more or less. The aging/wear manifests itself not only as reduced capacity, but also increased internal resistance; this means a worn out battery may support idle current for hours, but die in 10 minutes of high-current usage (like Skype, which is running wireless, speakers, and heavy CPU all at once). No, that's not a problem; in fact, the best (practical) thing to do is keep it on the charger all the time. Of course, the best thing would be to float it at 60% or so charge (for maximum shelf life), and run everything off wall power, but that's not really an option, so holding it full and running everything off wall power is second best. Holding it constant at any state of charge doesn't add to discharge cycles, while unplugging it and then replugging it when it runs low does.

Good advice, purchased new battery supposedly it is OEM from ebay. Not quite the battery life I remember, but it lasts a whole lot longer than 10 minutes. Thanks for the information.

Ok my problem was solved by a new battery, but after obtaining a new battery my friends n810 is still dying insanely fast. Skype kills the battery in minutes. What should i do?

The battery life remaining is estimated based on recent usage. The ARM is so good at throttling down to save power that the estimates fluctuate. Some aps or functions of those aps are very power hungry and can impact the estimates and for that matter charge life.

In my experience the batterymeter doesn't take battery aging into account at all. At some point it just realizes battery voltage is way too low compared to calculated remaining stored energy, and drops the battery bars rapidly.

As others mentioned previously, the voltage drop is even more significant with an aged battery, to the point where a really worn battery might cause the tablet to shutdown without warning under non-idle loads.

What's worse than keeping battery/tablet on charger constantly, is to run it down empty and the putting it in a drawer for a few weeks. Batteries hate heat and hate being left empty.

I've been experiencing the exact same problem. I even bought a brand new Nokia battery and, while it lasts a little bit longer than the original battery, the battery life is still quite short. I've reflashed the N810 many times and the problem persists. It's starting to look like it may be caused by the RX-44_DIABLO_5.2008.43-7_PR_COMBINED_MR0_ARM firmware. I'll reflash to the previous version to see if the issue goes away.

After a couple more reflashes I've tracked down the problem. For some reason, GPS was turned on but the GPS indicator wasn't showing in the Status Bar.