Winter is coming (eventually) and I need a generator this time around.

March 17, 2021 5:09 PM

My tiny mountain village often has power outages during storms. If I needed to keep a fiber optic internet modem, wifi router, my Macbook Air, a smart phone and a lamp running for around 3 working days (so 24 hours total), what wattage do I need to buy? What kind should I get? (specifics inside)

I have gone to so many websites trying to understand how to calculate running time, and I am failing. I can't seem to figure out how to calculate running times for different generators for these items. I don't know what specific modem or router I will end up needing to power, and all the calculations use amps so I'm not sure how to do this. I'm reaching information overload and need some wiser heads to guide me.

My situation: the community hall across from me is getting fiber optic internet in the next few months. If the power goes out, I'd like to be able to take a generator over there and plug in my stuff so I can work. My house's internet currently requires power in 3 different places to work (don't ask, ugh), so I'm going with working at the hall for now.

I am open to pretty much anything as long as it's not too expensive, portable, and reliable. I'm even down to make my own battery / inverter if the components are significantly cheaper to buy separately than a Jackery and someone can point me to a decent tutorial. Gas or propane is also fine. But I definitely need to know how much run time I will get from one tank of fuel or one fully charged battery bank. I also have a Prius, if that is something I could use (again, idk how much run time it would have with what I'm trying to power). I don't need a whole house generator, just something that will let me work remotely without too much hassle.

Thank you, Mefites!

posted by ananci to Home & Garden (16 answers total)

Best answer: Most generators (around ~1000W) will have a minimum time based on their lowest possible run time.

For instance, one of the best generators around, the Honda EU1000i, will run for 6.8 hours at it's least consuming mode (https://powerequipment.honda.com/generators/models/eu1000i).

You could aim for a smaller battery (or batteries) to see you through a single day and then top that up via your car, or with a gas generator.

Homepower magazine is no longer published, but their archive is full of good advice about sizing and building power systems, some like you require:
Homepower Magazine


But the easiest would be a basic generator, and however many gallons of gasoline at it's minimum load. You would be no more than 200W even with all those devices going full charge.

(Estimate: 20W router, 20W AP, 10W charge phone, 45W charge laptop, 5W lamp).

That's 100W, in 8 hours it's 100*8 or 800Wh. In reality, all the devices except the lamp will be far below in normal operation.
posted by nickggully at 5:49 PM on March 17, 2021 [2 favorites]

My dad just bought a bluetti For off grid camping and can’t stop talking about how great it is.
posted by rockindata at 6:02 PM on March 17, 2021

You could buy a Kill-A-Watt meter to estimate your usage. Plug a power strip in and all your devices into the strip, then measure watt-hours at the end of an average day's work.

I'm wondering, though, does your fiber optic modem work when the power goes out? Is tethering to your phone's internet an option? Mobile towers have backup generators, they sometimes last longer than the wired internet. But it really depends on the local ISP, you'll have to ask, or know from experience.
posted by RobotVoodooPower at 6:16 PM on March 17, 2021 [2 favorites]

Best answer: You should be able to run all that from a couple solar panels and a battery that you keep charged. Blizzards are often followed by bright sunny days. Prius and an inverter and longish cord would also work.

Will Internet service be up in an outage?
posted by theora55 at 6:26 PM on March 17, 2021 [1 favorite]

Most generators I know have to be hooked up permanently to the mains (where the power comes into your house). It sounds like you think having to use three different power outlets would be an impediment, but it wouldn’t. Do you have permission already to use a generator at the community hall? Usually it is a liability issue and common structures do not allow something as potentially dangerous as a generator to just be plugged into a public space.
posted by saucysault at 7:23 PM on March 17, 2021

I'd like to be able to take a generator over there and plug in my stuff

As well as your own stuff, at a minimum the hall with need their fibre modem & router to be powered - can you do this?
posted by HiroProtagonist at 7:28 PM on March 17, 2021 [1 favorite]

Best answer: Will Internet service be up in an outage?
I can't speak for your location, but in South Africa during our frequent load shedding, fiber internet continues to work when the power is off. This is only for 2 to 4 hours at a time, so I'm not sure if this would still be the case for extended periods.

For reference, if you have a devices specifications, you can use:
Power (watts) = Current (amps) * Voltage (volts)

My ONT specifies 12V, 1A, so 12W.
My router is 9V, 0.6A, so 5.4W.
(these appear on the low end for devices, so I'd err with nickggully's estimate above)

To keep just the internet on, I use a 100W battery UPS that would last just over 5 hours. This won't be enough for your situation and additional devices. Going for custom inverter + battery solutions is a common approach here where you can size the batteries to your needs, but I can't help with further details.
posted by Gomez_in_the_South at 8:25 PM on March 17, 2021 [2 favorites]

Best answer: For a generator the only spec that matters is the power output: you can always add petrol if the tank is running low, and with a few 20l jerrycans stored in a safe way you can keep going for weeks. And even the smallest petrol-powered generators can easily handle the 100W that nickgully estimated for your load. The ones on this page can supply 10 times that, except the Jackery which is a power pack (the USB power bank's bigger brother), not a generator.

Power packs are different as they do have a finite runtime, after which they need to be recharged from the mains, or with a number of models, from a car battery. Which you can do with a petrol-powered generator you have at your house, running to keep the fridge on (for which even a small 1000W generator is also quite sufficient) . Advantage is that a power pack able to supply 100W for eight hours is quite a bit lighter, has no moving parts and no exhaust, so it's easier to lug a power pack across the road and plop it next to your table in the community centre.

For your own situation there are also battery packs that can sit between a router, modem or some other network device and its power supply. Those of course have to match the voltage the device runs on as well as having matching connectors, and for every amp-hour the battery pack specifies (or 1000 mAh, as Bigger Numbers are Better), it can run roughly one hour. Search for "router UPS" or "mini UPS". This is better suited to taking care of shorter interruptions, as you now have to unhook these packs and the power supplies and recharge them plugging them into a generator as they run out.
posted by Stoneshop at 1:05 AM on March 18, 2021 [3 favorites]

Response by poster: Couple of clarifications: I am not hooking anything to the main power. I would be running an extension cord through a window and and plugging all powered components. I am allowed to do whatever I need to be able to work, including running a gas generator, although for politeness I would like to be as quiet as possible as sound carries pretty far here and people prefer quiet.

Unfortunately I have no cell service there at all, which is why this question even came up.

The fiber internet will still work in a power outage. Heck, our regular internet which is beamed over to a dish (ok, my neighbor's dish) still works in a power outage if you can power the modem and router (and the repeater router in between our houses). It comes from across the lake, so they usually have power even if we dont, and they have massive backup generators in any case.
I am using the hall because the landscape prevents me from putting a dish on my property, since its line-of-sight and there's too many trees and rocks in the way. We'll get fiber at my house at some point in the next 2 years, and then I will use said generator/power bank at home.

Thank you for all the replies so far! Keep em coming, I wish to know all :)
posted by ananci at 9:14 AM on March 18, 2021 [1 favorite]

Response by poster: Also we dont have enough sun for solar power here. We're in a low spot surrounded by trees and get maybe 3 hours of direct sun on a good day in the winter :(
posted by ananci at 9:21 AM on March 18, 2021 [1 favorite]

If you want a three-day runtime I think you need to go gas, a Honda EU1000i and a couple of gas cans would be more than enough, and pretty quiet. Heck, you could power a small space heater too.

You could run your electronics through a battery/inverter like a Jackery 160, which gives you flexibility to run for a few hours if you have to turn off the generator for some reason.

ALSO ... make sure you operate your generator safely. You need the right length and gauge of outdoor extension cord, and keep the generator far away from your cracked-open window. You might get some foam tape to reduce the cold coming in, but that won't protect against carbon monoxide getting sucked in, so be careful.
posted by RobotVoodooPower at 10:33 AM on March 18, 2021

If you (and the people living around you) want quiet: get a Jackery rated at 800 to 1000Wh, which will allow you to run a 100W load for 8 to 10 hours, a full working day with a bit to spare. To recharge it, you have one or more car or truck batteries and a mains charger that can do 'maintenance charging' (i.e. permanent trickle) somewhere in a well-ventilated space that doesn't drop too far below freezing. Total battery capacity should be 4 to 5kWh for three days worth of charging the Jackery, so about 400Ah if using 12V car batteries, and 200Ah with 24V truck batteries. Jackeries can charge off 12 to 30V, so there's no further voltage conversion required. At the end of the day you connect the depleted Jackery to this bank, and the next morning you're good to go again.

Once mains power comes back, the charger starts pumping fresh electrons into that battery bank, and after that's finished you're set for the next storm.
posted by Stoneshop at 10:58 AM on March 18, 2021 [2 favorites]

Adding details to some of the above:

1. most battery-pack type generators and nearly all UPSes have LONG recharge times compared to their runtimes, which is often the opposite of what you want during intermittent power situations. E.g., you'd want to charge for 1 hr on the generator, run for 4 h off the battery. Your typical UPS is more like 4 hr charge for 2 hr runtime. This just comes down to battery chemistry and how the systems are sized to keep costs down. Even for LiNMC-based packs like the bluetti mentioned above, it'll take 3 hr for a full charge (though you'd be able to run for something like 24 hrs on that given your tiny loads!). Just make sure you check the tech specs.

2. If you can afford a Honda EU1000i (or any of the EU*i series), you won't be unhappy. It's costly for what you get but probably the nicest common generator on the planet right now. It won't run your refrigerator or your well pump but given your light loads it'll basically be able to idle at minimum speed (longest advertised runtime) and keep your equipment on. Safely store a few cans of gas (no-ethanol, if you can find it locally, so it doesn't spoil) and run the generator every few months to keep things oiled and make sure it works.

If you want to go pure battery, you'll have to A. homebrew a system with lots of wiring and breakers and such or B. pay a not-inconsiderable premium for something like a bluetti or Jackery.
posted by introp at 11:08 AM on March 18, 2021

It won't run your refrigerator

Eh, even a largish fridge, if it was made this century, will take maybe 300W to run, double that on startup. This is well below what a 1000W generator can deliver.

And about sound carrying over long distances in an environment like yours: I was camping on the edge of a lake, somewhere in Central Sweden, when I noticed the sound of someone sawing wood. With a handsaw. It came from the other side of the lake, which my map told me was about 4km wide at that point. Apart from that, it was dead quiet.
posted by Stoneshop at 11:32 AM on March 18, 2021

Another thing: If maintained properly, a gas generator like the Honda will last maybe 2000 hours of runtime, which is 250 8-hour days. Even if you use it 25 days a year, that's a decade or more of use.

Batteries have a lifespan measured in cycles, but also in years. To get a lead-acid battery bank to last that long, you've got to keep them above freezing, trickle charge them properly, make sure they're matched, monitor them in case they go into thermal runaway, etc. More likely they'll last 5 years or so.
posted by RobotVoodooPower at 1:37 PM on March 18, 2021

Eh, even a largish fridge, if it was made this century, will take maybe 300W to run, double that on startup. This is well below what a 1000W generator can deliver.

In my experience, you're absolutely right about the running power (300 W), but wrong about the starting power. My fridge, by way of reference, takes about 105 W to run, but about 12 times that momentarily at startup.
posted by Juffo-Wup at 3:12 PM on March 18, 2021