Apc APC SMT3000C APC SMT3000C (Open Box)

I know this experience is probably atypical, but having this hardware removed from my rack is better than having it installed. As far as I can tell here is the behavior of the APC UPS in my rack: If the grid goes out, there is a facility battery that picks up, but with a small delay. The half second dip is enough for the UPS to kick into protection mode (as expected). Normally, what should happen next is that the UPS would return to A/C operation a few moments later. But for whatever reason, be it a bad sensor, bad software or something about the energy coming from the batteries, it literally refuses to switch back to A/C. Then, predictably, it dies which hard kills the entire rack. But the UPS is still on, of course, because there is A/C power and still refusing to turn anything on. So I have to manually override it on the menu on the front of the device. Only then will it try to power everything up and there is about a 50/50 chance of it just cutting power to the whole rack again. I've lost a 15TB HDD like with this behavior. Additionally, I purchased two new batteries for this unit after it reports them EOL. After a couple months it will report the battery EOL again.