My web site runs on a Pi and I want it and my laptop to run for as long as possible during a power failure. I'm looking for a UPS for about $US100.00. An orderly shutdown of the Pi would be good but extending the backup period is much more important. My laptop doesn't need extra battery backup but the Pi and a router do. All interaction with the Pi is via Microsoft remote desktop. It seems that UPS software is a significant enhancement to the hardware and I would prefer to run it on the Pi because my computer is not always on-site.
Any suggestions would be very welcome and a recommendation of specific software or a particular UPS would be a bonus.
TBH if the router takes '12VDC' from a wall wart, or whatever, Id suggest the simple expedient of a car battery plus flaot charger, plus a switching regulator
formatting link
to drop the 12v down to 5V and power the pi from that.
Permanently.
You probably have several days of life in the average car leisure battery.
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For just powering the RPi, I'd look at either the Pi Supply UPS PIco or the Pimoroni MoPi
time and can also use larger LiPos. They offer a 3000 mAh pack which claims 8 hours runtime with the mains off.
battery in the 6v - 20v range, so using a 12v lead-acid battery (or a few in parallel) should cover more or less any amount of power outage you're prepared to pay for.
However, running a router is a somewhat different story. To power that plus your RPi you'll most likely need a UPS with mains level output to run the wall-warts for the RPi and router because they may want different input voltages. My commodity D-Link router wants 12v, so can't share a wall wart with the RPi.
While you can pick up mains UPS for under $100 they're really only designed to let you shut down a PC or EPOS system and may assume you'll be around to do a manual shutdown when you see the lights go off. That said, a 400 VA UPS might run your RPi and router for around 8 hours if the UPS and the RPI and router wall warts are 100% efficient. If we say that the UPS AC converter is 90% efficient and the wall warts can manage
80%, make that something under 6 hours runtime as an off-the-head guess.
====== If you want to go much beyond that in UPS capability, the costs go up. I didn't see anything on the low cost range that could tell my computer about power outages. We go through periods where the mains 'flick': the power drops for a few mS, enough to cause a PC's electronic mains switch to turn off and I decided that a UPS would be a good way to stop that happening and that it would be a good idea if it could let the computer know when the mains was off.
So, I did a fair bit of research before buying a UPS and ended up getting a Riello Sentinel Pro 700, which gives an off-mains runtime for my house server (Dual Athlon @3.2 GHz) of 55 mins and provides a serial link for notifying the server of prolonged power outages etc so it can shut down cleanly.
I could also run my router off it (4 mains outlets) but decided not to since there's no easy method of powering off the router at the same time as the server and leaving it sucking on a fully drained battery is a good way of wrecking it.
HTH
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martin@ | Martin Gregorie
gregorie. | Essex, UK
org |
appears to be available for Raspbian. Supports most if not all UPS's out there. It's a client/server model. Server on the Pi with the UPS connected to the Pi (probably by USB these days). Server monitors the UPS and can shutdown the Pi on battery low. Client on laptop networked to Pi could shut the laptop down when the power goes or a minute or two after.
Some do have USB ports for connection to a host PC but not all.
Surely the UPS shuts itself down when the battery gets towards flat? After signalling "low batt" to the host equipment a minute or two earlier. Mine does.
As for makes, I'd be a bit wary of APC units. They have a habit of cooking the batteries. The charge rate is set for quick recovery and restart after an outage but doesn't switch to a trickle/float level when the batteries are fully charged. Don't know if the buget models are any better mind.
I have seen this, the flatteries on mine were so cooked there was no way they were ever coming out again the plastic was bulged round the metal of the case. Lbooyd hot it were TAAAW.
WHAATTT!! REAALLLY! Oh ye gods that's insane.
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Steve O'Hara-Smith | Directable Mirror Arrays
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Seen that in a rack mount unit. Would have required serious metal surgery to get them out. Last example was my Smart UPS 700, they almost caught fire:
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But it sells battery packs, that and the routine testing unless you turn that feature off.
I've "got at" my APC UPS and it now charges at a float rate much closer to what Yusa say is the float rate for 12 V 7 AHr batteries. Takes much longer to reach the 15% charge level before it'll restart but WTH the unit now sits at just over 30 C and doesn't feel warm instead of over 40 C and decidedly warm. I've also added a speed controlled fan in the slot that would have taken an SNMP card.
FWIW I'm running my Riello in 'online' mode, i.e. the battery is continuously in circuit and being charged at the same rate as the external load is pulling power from it. All surfaces are cool to the touch and its reporting an internal temp of 30C.
So, going upmarket a bit at least got me decent battery management. IIRC it uses a pair of 2.7 Ah 12v SLAs.
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martin@ | Martin Gregorie
gregorie. | Essex, UK
org |
$100 would buy a lot of internet hosting for your web site. Maintaining power during failures is no longer your problem.
I used to run various internet services from a low power Linux machine at home. The more users I had the more I'd worry about power fails. I was working away from home more and that meant having to explain to my wife and family about restarting stuff if the mains failed.
Then one day I got a cheap VPS and moved everything from home to the VPS and haven't looked back. Running servers from home is, IMHO, a mugs game. Stick them in a data centre and pay a few pence a day for someone else to worry.
Maybe, but I'm more interested in the weather at my premises than the temperature in a basement a thousand kilometres away :)
I do pay one dollar a month for automatic failover to a web host that contains the minimum information about my business.
I want to retain Internet access so the modem/router still needs power. I assume the Pi would not need much extra power and would provide a web page with details about the power supply.
If it was doing a 24x7 job it would probably be on some sort of UPS, but as it is doing almost nothing apart from being kept up to date and backed up, so keeping it powered would just waste power.
My main development activity is currently on the UPS supported house server and, as it is mainly Java programming and web page maintenance, is not suitable for transfer elsewhere.
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martin@ | Martin Gregorie
gregorie. | Essex, UK
org |
Fair enough. Looking at the stuff here, the power needed for a Pi fades into insignificance compared with the power needed to keep it online, i.e. cable modem and router.
Does your internet feed stay active when the power fails? It seems my ISP's cable equipment is battery backed up for about 30mins. If the power is off for longer, when my power comes back and the cable modem starts up it can be another 10-20minutes before it regains sync as the street equipment restarts etc. If it only stays up for 30mins or so, you can decide whether you need to bother keeping the Pi running or not. No point keeping the Pi and router running for hours and hours if there's no connection possible.
That only makes you happy as long as everything happens to work OK. Once a problem develops, you will know that the "someone else" that you appointed does not rate your problem at high priority and you are at their mercy to get your system back to working condition. That may take long, or it may never happen. Usually the best you can expect is to get your money back for the time period that it has not worked. And because it is a cheap service, that will be little money.
Not entirely, you have the option of taking the problem back and giving it to another someone else. At least you do if you have been as sensible as Martin and kept your data at home too.
--
Steve O'Hara-Smith | Directable Mirror Arrays
C:>WIN | A better way to focus the sun
The computer obeys and wins. | licences available see
You lose and Bill collects. | http://www.sohara.org/
You buy a hosting service to meet the service needs. A webserver currently running on a Pi in a domestic environment is not really going to need 24/7 support, fail-over systems, redundancy, co-location, guaranteed service levels etc. Apart from the fact it takes local physical input, it would be the ideal candidate for hosting in a low cost pence/day environment.
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