I’m looking to buy ups as I have few power outage (last between 1 to 5 seconds max) where I live but I have never used one so don’t know what specs should I check for
Ideally I will plug my 3d printer (about 100-160w when printing), a pi 4 with nvme drive (no idea of wattage) and a mini pc with n100 processor (around 10-20W)
Thanks for your advices
My experience has been that current UPSes tend to give a pretty limited runtime, more-limited than you might think, and are surprisingly-expensive for the capacity that they do provide.
The reason one historically really wanted a home UPS wasn’t necessarily to run a machine through a power outage, but to provide time to save any work and shut that machine down. We used to use filesystems that could become corrupt if they weren’t brought down cleanly. You could maybe run a machine for minutes, not many hours.
So it was important to warn (and maybe auto-shut down). UPSes are good at that. You have beeping alarms, software to auto-shut-down a machine cleanly when the battery gets low if someone isn’t around, software to notify a single attached computer about the battery level.
But with the combination of filesystems that don’t do that plus software that auto-saves, that’s less critical. What I think most people want is just more runtime, having a shot at making it through short power losses.
I think that today, if I wanted to provide longer-running resistance to power outages, I’d probably look at one of two things:
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For a device or two, “power stations”. These sometimes get called “solar generators”, despite not generating anything, because manufacturers are marketing them as an alternative to gasoline/diesel generators for power outages. All-in-one box with batteries, charge controller, and inverter in one little case. This kind of thing. They won’t beep to warn you that the power is out, and they won’t have software (or interface) to tell a computer to automatically shut down.
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For larger capacity, a “grid tie solar system”. These tend to be extensible, with separate 12V (or 24V or 48V) batteries or the like and separate boxes for the battery charge controller and inverter. You don’t actually need to hook any solar panels or other power sources up to it (though, hey, maybe you decide that you want to do so), as the battery charge controller will charge the batteries from the grid as long as the grid is providing power. You can select a size for and replace the batteries and inverter and charge controller separately, and you aren’t constrained to use a single vendor for all the components.
I would look to see that the inverter in question provides “pure sine” output. Some inexpensive inverters provide a square wave, and some devices don’t much like this.
EDIT: Ah, just saw your new comment:
Power outages are usually very short (few seconds max).
You may not care about keeping the system running through longer outages, then, unless you’re also worried about longer ones.
This is absolutely the correct information. I sold UPSs for years and the general consensus is that if you want more than 5 to 10 minutes of power, then you want to go with an actual generator solution
Saying that, UPSs tend to be used in industrial environments to keep machinery running until the generator starts up and can accept the load.
And in the case of a 3d printer after so many seconds of now power what id use one for would be to cut off the bed and hotend, list the head and then run the part cooling fan full blast until power went out.
The print would be ruined but less likely to have heat creep and jams when the power goes out leaving the existing melted plastic to wick up into the heat break when the cooling fan goes out. And less likely, but technically possibly, the nozzle, still not sitting on one piece of plastic with enough heat to scorch or worse.
What sort of grid-tie systems are you thinking of?
I ask because I’ve been considering something like that and am finding nothing but things which have an internet connection back to the manufacturer. Some US states apparently prohibit charging batteries via the grid outside of certain scenarios. Abiding by that is fine, I’m not going to charge illegally. But I’d still like a device that is 100% not controlled remotely by some other party.
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Thank you!
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I can’t help much on the power draw side of this question, but one thing to look out for with a UPS is some sort of communication option. (Usually NUT over ethernet, but there are some USB options too.) Most modern UPS brands will have a plugin you can install on your Raspberry Pi and Mini PC that allows your UPS to signal, “Hey, I’ve got 3% of battery life, you actually need to gracefully shut down now.” It’s mostly useful for NAS applications with spinning drives, but it could help save your Pi’s SD card potentially.
It’s a pretty standard feature these days, but the cheapest of the cheap will omit it.
I have nvme setup on my pi 4 (I know it’s overkill for that purpose but already had pi setup like this prior to klipper), that being said I will definitely look at getting one with communication control even if power never goes down for more than a couple of seconds
Noise! They are louder then you think.
Ability to mute the alarm.
Bonus points if you can connect it to a computer to automatically shut it down cleanly.
Optional, battery expansion out of the back
Keep in mind, UPS’s should be in well ventilated areas, they can off gas hydrogen and other explosive fumes depending on the battery type
How safe is it to keep a lead acid battery UPS in a relatively/loosely closed space about the size of 8 of those UPSs?
A typical UPS uses sealed lead acid batteries. Those don’t vent hydrogen unless something goes really wrong like severe overcharge or a short circuit.
Just make sure it has enough ventilation to keep it from overheating. They are usually around 80% efficient, so it will produce around 40 watts of heat with your load while it’s on battery.
Didn’t think about noise and that’s important to me so thanks, is there anything special to look for the battery to make sure it can support my 3 devices at the same time? Like amp or other electric specifications?
Look for devices, and read their specification sheets. They will tell you how much wattage they can support and how long they can support it for. They might do it in different units you can convert to wattage.
Do you need your devices to stay on for prolonged periods of time off the battery? Or just long enough to shut down? That will have a huge impact on how expensive your UPS will be.
You can add up the wattage of all of your devices, and see what the maximum is. Or you can get a $3 power meter and measure it empirically. Most UPS’s will set off an alarm if you’re drawing more power than they could support if they had to switch to the battery
Power outages are usually very short (few seconds max). Are fanless ups ok or should I stay away from it. The one I’m looking out at the moment is Eaton Ellipse eco 500
If you only need it to skip the power outage, I would look at something in the range of 800W to 1000W in an online ups.
This wattage should run your devices for 5 minutes or so, as you have quoted them. The online UPS will always run its load off on the battery, so there is no swap over time. Other types will be fine for a PC or normal electronics, but the hitch in power could cause a defect in the 3D print.
Thanks
Whatever would support the combined max wattage of the devices you will connect to it. Ideally something that can handle 50-100% more power. You can control some UPSes via USB or network, so you can hook it up to that mini pc or Pi (why are they separate?) and run NUT on it. You could technically pause a print/shut down a computer/Pi if an outage is more than x seconds to reduce power usage and get through one that you otherwise couldn’t.
“why are they separated”, not sure what you meant, mini pc is acting as a server for a few usage and pi is dedicated to klipper.
Yeah, that explains stuff. I thought you might have had some stuff on Pi that you could’ve been running on the PC. In that case I’d recommend that you run the NUT on RPi, and set it to pause print on a power failure, possibly change CPU scaling (i.e. to “powersave” CPU governor if you’re running Linux) on the mini PC, or even possibly shut it down in an event when the power outage lasts longer than a minute.
Actually I could even run Klipper on mini pc but would need a very long usb to reach printer and thought it wasn’t ideal. As for the mini pc, I’m running proxmox but I’m far from being an expert so not sure if I can manage CPU scaling.
Actually I could even run Klipper on mini pc but would need a very long usb to reach printer and thought it wasn’t ideal.
USB has some serious length restrictions, but you can either add a repeater (which in this context, is probably a hub) or use an optical cable with transceivers at each end, something like this.
The hub is probably cheaper if you just need one extra hop.
I am too, and it is really easy to do so. Look up “Linux cpu governor”. NUT (which is the most common UPS management software for Linux) can execute commands, start timers at different events from UPS.
