The battery can be replaced, just not by the user. (Unless the user has a little experience working on small electronic devices.) Go to a Best Buy, ask where the Samsung desk is (it's in the cellphone area) and ask the Samsung people if they can give you an idea of how much it would cost to have the battery replaced. Figure about half of that if you have a good local cellphone repair shop - Samsung charges a lot for labor.
When do you replace a tablet?
1) When the cost of replacing the battery makes less sense than buying a new tablet.
2) When the tablet is so old that it can't run current apps.
3) When the tablet doesn't work, and the cost of repairing is too much compared to buying a new one.
4) When you just want a new one and don't care about wasting money.
BTW, 30 months on a battery is about normal if you take good care of it. Anywhere between 18-24 months is what a lot of people get (usually from running the battery too far down too often).
