APC SUM48RMXLBP2U Smart-UPS XL Modular 48V Extended Run Battery Pack

Several years ago, we invested in a 3,000VA 2U unit for a data cabinet at one of our locations. Best calculations at the time were that it would provide approximately 30 minutes of runtime.I specifically chose a modular unit, because times change, and I knew that at some point in the future, as we built out the cabinet, our power needs would increase.This unit contains two battery packs, whereas the UPS itself contains a single one. So, while it doubles the physical space of the system (2U for the UPS + 2U for this expansion unit), it effectively triples the runtime of the UPS.Installation, once the manhandling of the unit is complete, is fairly straightforward: connect the cable to the back of the UPS. From there, log into the UPS' internal web server (or use telnet) and just increase the battery count per the docs from APC. Done.Runtime before this unit was below 5 minutes. Latest calibration shows over 20 minutes with this unit installed, and of course, more units may be added.This kit comes complete with feet and rack mounting hardware. I suppose most of us will have these units rack mounted, but it's an added bit of flexibility that they can be used freestanding (sometimes, rack spaces are at a premium, and reserving 2U for a battery pack may be less than optimal).*** IMPORTANT NOTE ***This is *not* a UPS at all. It is an additional (expansion) battery pack for an XL model UPS. The model number essentially breaks down like this: SU = Smart-UPS + M = Modular + 48 = 48 volts + RM = rack mount + XL = eXtended Life (runtime) + BP = Battery Pack + 2U = 2 rack units high (or wide, when standing upright).Again, this is *not* a UPS. It will provide *no* battery backup protection unless you have a compatible UPS to which you slave this unit. See [...]