I have a Sony VPCEB33FM laptop running Windows 7, about 4 years old. It started showing a low battery warning and shutting down immediately after booting up, even with the laptop plugged in. The battery tested as fully charged. I can run the computer if it's plugged in and the battery is out, but it shuts down immediately if I install the battery.
I purchased another battery (used, but supposedly tested and working in a laptop) and had the same issue with the second battery.
A search for Sony VAIO battery issues indicated that this problem could be caused by a problem with the battery, the Sony battery monitor program (which I deleted, didn't help), a motherboard issue, or a problem with the laptop hardware where it connects to the battery.
Is there anything I can do to narrow down the likely cause?