[snip] I took the opportunity to upgrade our quality a little to a unit with Sinewave output and a display that might communicate more when it's getting ready to completely die on me: CyberPower CP1500PFCLCD PFC Sinewave UPS System https://www.amazon.com/gp/product/B0042 ... UTF8&psc=1
I'm wondering if anyone else has experienced this failure mode or could explain to me a good reason this unit can't just act as a surge protector when it's battery goes bad? I went with the Cyberpower because I have one at home that is at least 10 years old and has never given me an issue. Maybe it will fail in the same way some day, but for now I didn't want to pay for batteries in a unit that is going to leave me totally stranded that way in the future.
EDIT: I forgot to ask - what do you guys do to protect against this kind of failure mode? Our servers aren't high-end enough to have dual power supplies that I could plug into separate UPSs, but other than that is there any other solution you guys have come up with?
IMHO that UPS "upgrade" is not much from a quality perspective as both are considered "backup / standby" UPS designs. Sure, the Cyberpower units are lower cost and seem to be reliable, but sometimes it's better to spend a few more $$ for a higher quality unit. When I want a high quality UPS I choose Eaton over APC. Sure, APC builds a reliable product, but I like the monitoring features of the Eaton units when using "NUT" ("Network UPS Tools") on Linux. Even the Eaton "Eclipse" series has very good reporting while the higher end Eaton "5S" workstation/home-use series monitors everything that NUT can monitor.
There is a price difference between Cyberpower and Eaton "5S"; the Eaton "5S" is almost double the price, but you get a "line interactive" UPS where batteries can be "hot swapped" whereas the Cyberpower unit has to be powered off and then almost torn apart to replace the batteries. I have owned both brands and different models in each brand for years now.
As for the UPS that powers off after it has beeped at you incessantly, yes I have seen that. I have seen 2 causes for it: (1) a bad UPS (something shorted inside that defied efforts to repair it); and (2) dead batteries in a "backup / standby" type of UPS. A "line interactive" UPS should run even with dead batteries based on my own experience, provided the AC power is on (obviously). My older model Eaton "5S" units will run with dead batteries with the AC power on. My Cyberpower units will "act strange" with dead batteries when on AC power. One of them would power off while the other would run. Having a "line interactive" UPS unit is nice because you can change batteries at any time without having to power off it's "load" or even disconnect any exterior cables.
How do I protect against UPS failures?
I buy good quality UPS units like Eaton for my servers. For my network gear at home I use Cyberpower since the network gear is POE powered and the main POE supply is on a high quality UPS unit. I monitor all of my UPS units using "NUT". I configure all of my attached servers (after tracing their power cables) for "graceful shutdown" when "NUT" reports a UPS is running on batteries. I make a plan to change UPS batteries at the 3 year mark. If a UPS unit has been "behaving well" and the "NUT" data doesn't show any battery charging or battery voltage issues, then I revisit my plan around every 6 months up to the 5 year point. After 5 years it is generally a good idea to replace the batteries.
Hint: Another nice thing about a "line interactive" UPS is the ability to remove the batteries while the AC power is on so you can check each battery block's voltage after it has been disconnected from the UPS and surrounding battery blocks. I have done that to find "weak" battery blocks, which is a battery block that is not providing it's rated DC output even when charged possibly due to dead/dying "internal battery sections". Yes, this test procedure is risky since you are "rolling the dice" that the AC power does not go out on you, but sometimes it's a necessary risk.
What do I look at in the "NUT" data?
I start with "actual" and "nominal" values for "battery voltage"; both Eaton and Cyberpower can provide this in many of their units and it can indicate if the UPS has a bad or weak battery. I look at the "Battery Charge / Load" chart which is commonly available in most UPS units since a bad/weak battery will not charge to it's full potential. I look at "Time Left"; "runtime" when on battery and generally available in many UPS units to help me decide if UPS "loads" have to be "rebalanced" or a new UPS is needed. The graphs of AC line quality can be useful for detecting AC power issues when you are not there; also commonly available in UPS units.
How do I monitor using "NUT" software?
A Raspberry Pi connected to the UPS using the USB monitoring cable that came with the UPS works well for me; about 5W power consumption, totally quiet, and no distracting lights. I have also used old "PogoPlug" units (about 5W power consumption, totally quiet, and no distracting lights) and old Intel D510 Atom-based mini PCs (about 10W power consumption, totally quiet, and no distracting lights) as UPS monitors. As long as the monitoring device can run a commonly available Linux distribution, then the NUT package is likely in the archives for that distribution; I have not used "NUT" on a Windows OS. Even an "always on" server can be used for monitoring since "NUT" requires very few system resources to run and the software is designed with "security" in mind, like "dropping root privileges" after startup. To monitor the "NUT" data I can use the tools in the "NUT" package for a quick look, but for historical data gathering I use "Monitorix" on a dedicated monitoring platform that monitors many things along with "NUT". I haven't spent enough time getting UPS monitoring into my "Cacti" installation since my "Monitorix" is simpler to configure & use.
Yes, everything that I have said so far sounds like lots of work, but the "automation" does all of the "tedious routine work" while I make the decisions on when to change batteries and add UPS units. I place a label on all of my UPS units showing when I last replaced the batteries. I add a calendar reminder for myself to periodically check the batteries on/around the anniversary date of that battery change.
I have not configured any "alerting" mechanisms for my "NUT" installation as that aspect is not important to me in my "home use" case.
A piece of advice on UPS batteries: Buy UPS batteries that are designed for use in UPS units whenever possible. I can get the UPS-rated battery blocks I need at the local "Batteries Plus" store for about $10 more than a "standard" battery block; others may prefer other battery sellers. A UPS-rated battery should be more expensive than the same size battery that is not UPS rated, when such comparisons are possible. So what's the difference? A UPS-rated battery can be "deep cycled" (completely discharged) more times than a "standard" battery block, and that requires (at least) different construction in the plates of the battery. The "standard" batteries might handle a couple (about 2 to 3 in my experience) of "deep discharges" before they fail to recharge (dead battery), and then it's time to replace them. Finally, UPS-rated batteries should be clearly identified as "rated for UPS use" by the manufacturer; when in doubt, check it out thoroughly.