Between work and my own hobbies, I basically always need access to a PC. So, after a recent power outage, I decided to repurpose an old Raspberry Pi and an Anker Power Station to work as a small backup Linux desktop in an emergency.
Despite the meager hardware specs, it actually works better than I’d hoped, and I can still use it for my other projects in the meantime.
For this setup, I’ve paired a Pi 4 B (8GB) with a SSD in an external USB enclosure, a small portable monitor, and a few other essential peripherals.
Since the goal is to be able to function without power or internet during an outage, I’ve also taken an offline-first approach to software. I installed LibreOffice, Joplin, and migrated a bunch of media files over so I wouldn’t rely on streaming or my local media server, which is going to be off.
When it isn’t working as a backup desktop, I use the exact same setup for testing low-power Linux distros, some self-hosted applications, and more—a backup desktop doesn’t need to tie up your equipment permanently.
The Pi 5 is certainly more performant than the Pi 4, but the Pi 4 consumes less in terms of pure power. The Pi 4 has an idle draw around 3 watts (W) (with peripherals), and the Pi 5 can reach nearly 9W under load, while the Pi 4 tops out around 7W.
Because of that limitation, the Pi 4 will happily run on a standard 15W power supply, while the Pi 5 theoretically requires up to 27W. Depending on which battery bank you use for a backup, that could be an issue. The Pi 4 runs comfortably off a USB-C port on my power bank, which is actually an important way to minimize power draw.
Of course, the Pi 5 is between two and three times faster than a Pi 4, which tends to be most obvious when you’re launching apps or booting up. It also has a PCIe lane that can be exposed via an optional hat, which is incredible if there are any high-speed devices in the mix.
The extra power used—and larger power supply requirement—are probably worth the tradeoff if you can get a Pi 5 at a reasonable price. However, I already own a PI 4, which made the cost proposition a no-brainer.
If you’re buying new, you should size your battery against a measured draw or the maximum theoretical draw, not a runtime chart provided by the manufacturer. They tend to be optimistic, which can be a problem for something you rely on.
For example, assuming my whole setup pulls 12W, a 1000 watt-hour battery will be able to power things for 83 hours, or about 3.5 days. The same battery would be able to run my desktop for only a few hours (if I’m lucky) or a laptop for a day or so.
Large power stations usually have two very different types of output: AC and DC. DC outputs include things like USB type A, USB-C, and 12-V auxiliary power (cigarette lighter) ports. Those ports tend to have fairly little overhead.
AC ports are a completely different situation. Batteries output DC power, which means that your power station must first convert DC to AC before you can actually use it. The conversion process uses an inverter, which can easily use 10W to 30W while it is idle but switched on. When they’re in use, conversion isn’t perfect either. Some energy is lost during the process, often between 5% and 15% of the total draw.
Here’s your sine.
So, if you’re powering a device that only requires 10-12W DC, the overhead from the AC inverter could triple your energy consumption.
You should run the Pi directly from the station’s DC or USB-C output and leave the inverter off unless you actually need it.
I have five 100W solar panels that I can attach to my battery whenever I need them, which produce more than 5x as much as my setup’s real-world draw in a 24-hour period.
In practice, that gives me margin to cover cloudy days without worrying about running down the battery.
I have a Starlink Mini on hand for emergencies and when I travel anywhere without cell service. It has proven to be indispensable when there is an outage and I need to get online to check for updates or work.
The Starlink Mini draws somewhere around 20W while operating, but it can surge up to 60W while it first acquires a signal.
Just like the Pi (and any other devices, really), you should run the Mini directly off of DC if you can. Depending on your system, you may have a USB-C port that can meet its power requirements. Otherwise, a cigarette lighter port is probably your best option.
I initially cobbled together my solar-powered Pi with a powerbank for emergencies, but I’ve also used the same setup on the road a handful of times. The Pi can also function like a media server, a NAS, a VPN, and a Pi-hole if you set up your storage correctly.
Even if you’re using a laptop rather than a Pi, the same general principles apply. Use power-saving mode when you can, and try to minimize your network usage. Cellular, Wi-Fi, and Bluetooth all add to your power draw. Additionally, if you can charge your laptop using a USB-C port rather than the power station’s AC port, you should—it’ll make a noticeable difference in your battery life.
We want to hear from you. Share your perspective in the comments below, and please keep the conversation respectful.
Your comment has not been saved
For your backup power, be aware of Modified sine wave inverters as they are the cheap option. They can do damage to electronics and motors. Spend the extra money for pure sine wave, which Will be advertised on the listing if it is there. If the inverter doesn’t say what kind it is, it’s modified sine.
Also make sure to check any battery, solar charge controller or especially the solar ‘generator’ (which don’t generate anything, the power is collected by connected devices like solar panels [pv]) for reviews and verification that they function safely as there are a lot that don’t have thermal runaway fuses to prevent fires.
I have a whole house 40kva generator with autostart and ATS so I have that covered
That’s a lot of work to just have a limited use computing device powered.
Instead I went with a 6 KW inverter generator, a port and lockout type switch installed on the outside of the home. It can use 2 fuels for power (gasoline and propane). I just use propane, it mitigates stale gas and gummed carburetor issues.
It will run the refrigerator, sump pump, lights, internet, a few PCs, and a furnace in the winter.
If you have a power outage it’s probably because some other event is going on that causes more problems than just your internet going out.
If the power, or when the power drops off I don’t actually notice anything.
The inverter just switches over to use our solar and/or 10 kW battery system, takes a few mS so no glitches.
The best of How-To Geek, directly in your inbox.
By subscribing, you agree to receive newsletter and marketing emails, and accept our Terms of Use and Privacy Policy. You can unsubscribe anytime.
