iFixIt. How to Convert a Computer ATX Power Supply to a Lab Power Supply. Edit Article Edited by Abizarl, Krystle C., Jack Herrick, Vertent and 42 others Computer power supplies cost around US$30, but lab power supplies can run you $100 or more!
By converting the cheap (free) ATX power supplies that can be found in any discarded computer, you can get a phenomenal lab power supply with huge current outputs, short circuit protection, and reasonably tight voltage regulation on the 5V line. On most power supply units (PSUs), the other lines are unregulated. Russ Nelson.
The internal N800 battery is pretty studly, but there are contexts in which I don't want to have to swap out the battery for a spare.
Have to reboot the machine to do that and if you're trying to run a program for a long time or continuously, that's not acceptable. Plus you have to notice that the battery has run low and replace it.