Most UPS systems of quality will come with software capabilities. You can leverage this and just use a daemon to check the charge status every minute or so. If it’s ever off AC or reporting charge levels lowering, you can toss the system into a low power profile. This might accomplish what you’re trying to do.
Any poor quality connector can affect a sector scan and drive performance. Doesn’t matter if it’s connected to a corroded usb port or a bent internal sata, at the end of the day if you’re getting disk errors it’s best to measure using two methodologies/data pathways.