Network UPS Tools
The primary goal of the Network UPS Tools (NUT) project is to provide reliable monitoring of UPS hardware and ensure safe shutdowns of the systems which are connected.
This project attempts to monitor every kind of UPS, given sufficient interest.
You can also use this software to safely shut down your computer when the battery is low.
This can be scaled up, which means that multiple computers can monitor a single UPS over the network.
No UPS sharing hardware is necessary.