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Home: Enduring a power failure, UPS, VA and Latex


OK, we had a six-hour-long power failure here. Fortunately, Seattle City Light does a great job keeping people informed if you have access to the Internet at their outage page. You just call (206) 684-3000 to report one. And in our case, we were down from 930-1630 or so. The other interesting thing was that Comcast actually texted us that the cable internet would be down as well, so it is a good idea to have a cellular backup. So here are the things to know (and what to do to be prepared):

UPS per computer: What the heck is a VA?

Having a UPS is actually a good idea for delicate electronics. At a minimum, you want a surge suppressor because when the power goes out, it definitely transients and that is not good for delicate electronics. As an aside, the industry uses this notation VA rather than kWh (that is how many watts for how many hours can you deliver which is common with Electric vehicles). What Volt-Ampere and why does it exist? It's used when you are converting from the direct current in a battery (DC) to alternating current that is used to power most appliances. So to go through some math, with just DC, the Power P (in watts). Also as an aside inside an aside, I was originally using Katex to display these Latex equations, but it turns out Latex is actually built right into JetPack now which uses by wrapping around in dollar signs and this works inline \LaTeX&s=X

i\hbar\frac{\partial}{\partial t}\left|\Psi(t)\right>=H\left|\Psi(t)\right>

I've been using Cyberpower CP1500PFCLCD which has a true sinewave for desktop machines that costs $220 for the 1500VA/1000W version. The main issue is that these do not seem to have replaceable batteries so my old one is just dead now. This uses two 12V/9Ah Lead Acid batteries which are RB1290X2 for those serial numbers beginning CXX or RB1280X2B for serials beginning CR9, CXF, or CQC, and are user replaceable. In looking at mine, I have a CQC model so need the RB1280X2B which is $93 for a pair of 12V/7Ah lead acid batteries, and the RX1290X2 are 12V/9Ah batteries.

UPS for the network, servers, and cable modem

The other thing is to have UPS systems for the network, so we have two APC VA-1500 for the server room with one for the servers and the other for the network internally and the cable modem.

The other variety I use is the APC VA-1500 which has led acid batteries so they are pretty easy to replace. But they are really limited in the power they can store. I bought mine 11 years (?!) ago but they are still going strong thanks to the ability to replace the batteries (APCRBC163). The latest version APS VA-1500 is $200 on Amazon and the very latest model is a sinewave model for $270 with 5 outlets for the battery backup and five for surge protection and two USB ports but looking at reviews it looks like they really cheaped out on the construction so I'm not sure I would recommend these anymore. Ten years ago, they were the gold standard.

The other issue is that they are relatively short-lived. I don't know exactly what the 1500VA stands for (but this is really the amount of output that it can sustain). The specs say this will last about one hour with a 100W drain or 0.1kWh. That's not a lot. In this power outage, the Internet was gone pretty fast.

UPS with Synology and automatic shutdown

Another cool thing that you can do is that the APS UPS systems have a USB cable so that they can talk with a server like a Synology and tell it that the power is out and then the servers can shutdown not only themselves but also the UPS power supplies as well that way you still have reserve power. Ideally, you want a single UPS per server so that the shutdown happens gracefully, with Synology burning 100W or so a 1500VA gives you quite a bit of time and reserve to stop this kind of stuff.

I kind of cheaped out and there is one UPS for two servers, so I normally just have the Synology servers shut down. In the latest power failure, I also configured the UPS to shut down which was a bad thing as I had the cable modem incorrectly connected and lost the WAN but still had the LAN.

The correct way to do this is to put the networking pieces, the router, the switch, and the cable modem all on the same UPS. I can see my draw is about 100-200W, so I have about 30 minutes of power.

LiFePo4 UPS arrives!

Well, the good news is that so-called LFP or Lithium Iron Phosphate batteries are coming and they have such great power density and can stand 2500 cycles before dying. These aren't replaceable but you can get way, way more power from them. For example, we've had good success with the $200 or so Bluetti EB3A with 268Wh, this thing actually has about 2.5x more power. These are however not real UPS systems, but just battery backup, but you can get an idea of how cheap consumer stuff is this way.

You can also go the whole hog with a $5.7K Bluetti system with the AC300 and two B300 6.1kWh so the end-user cost is about $1/Wh now that would be 20 hours so nearly a day for cellular access. Or more reasonably AC200Max at 2kWh for $1.8K makes some sense given that this technology is moving so fast. It is still 20x more than the VA1500 so worth thinking about. The AC200P is a 2kWh at $1500 so actually not a bad deal at $0.75/Wh.

A Replacement strategy: Recycle Lead, buy LiFePo4 Replacements

So, net, net while the Lead Acid is cheaper, having a more reliable and larger supply is definitely better, so here is a strategy to feather in this stuff:

  1. As the Lead Acid batteries fail, which they do, the Cyberpower for instance stops charging after about five years, dispose of these via Goodwill or send them to a local lead acid battery recycler and then get Li-ion replacements.
  2. Get additional LiFePo4 backups where there is one for each server, one for the alarm system, and one for the network to keep everything running. With Cyberpower, you just unplug it all and there are front panel screws at the bottom of the case, you pull the front panel off, removed the fixed stand fro the upper battery and then pull themn.

Lithium Ion UPS Reviews

There are not many reviews of these things, but there are two classes, first are the real systems designed for the enterprise such as these $1-2K systems. You really have to think if you need these at home though:

  1. Vertiv Liebert. They have a variety of sizes, but the 1000VA/1000W version is $1790 and is just a 1U rack mount. This is actually pretty hard to understand how many kWh it actually has since the notation 1000W refers to the maximum discharge it can handle, so at 120V that's 1000W/120V or 8 Amps, then the notation 1000VA, but looking at the charges at 100W, it can last 115 minutes (1:55 hours) so it has 191Wh or 0.2kWh. So quite a bit more expensive than the consumer-grade UPS or the consumer-grade battery backup systems.
  2. APC Smart-UPS Lithium-ion SMTL1500RM3UC. Another option is the APC which has fallen down in terms of quality but is still a major player with a $2,100 on Amazon for a 1500VA system in a 3U rackmount and is probably 100Wh.

Then the cheaper option is just to start replacing the existing systems we have with LiPo batteries.

  1. LiFePo4 F2 REplacements for existing Cyberpower and APS UPSes. You can also for alarm systems get Lithium Ion replacement. This makes great sense for alarm systems that use these F2 tabbed systems anyway, they are more expensive but way more durable than Lead Acid. You do need to make sure that your you have a Li-ion charger which is a bit of a pain, but these are 12.8V batteries with a discharge rate of 0.5C with 0.2C preferred. The 10Ah has 128Wh so you should charge it at 3A. You can also them to replace the batteries inside the Cyberpower which fit the RB1290 UPS and these are user replaceable which is great.
  2. Bluetti AC300 and B300 Backup. Another option is to just put a battery backup system behind the UPS, so you are in effect providing more power to the existing UPS systems. This makes some sense given the price of the consumer devices since they don't need to be as hard-core about the UPS. As an example, a 3kWh system is $3700 which is 10-20x more than a single UPS. When combined with a PV350 350W solar panel, this is a pretty good option for poor man's off the grid and power outages.
  3. Of course the best answer is a Tesla Solar Roof and then lots of PowerWalls, but I'll leave that $40-100K expense for you to think about.

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