How much loss is there for a converter? I always thought that for the most part they were pretty efficient. Unless you've measured and found a difference, you might be trying to solve an issue that isn't a huge one.

I've been very happy with my Cyberpower setup, and the smaller one is powering my router and monitors. It's still 650VA, so will roughly match the time the larger one would keep my computer alive. I'm not running a server though, so it might still be low for you, but 12V 5A doesn't seem like a large pull.

What router? 12v5a is 60w max, which is not an unreasonable amount of power. A 1500va UPS should power it for like two hours or more.

You could easily wire it up to something like that. Take the power cable, cut off the wall wart, connect the positive wire (usually red, could be white) to the positive terminal, the negative to the ground terminal. Cut off the head of a power lead, connect the live, neutral, and ground to their terminals on the AC side. Plug your battery in, the power lead into the wall, and you’re done. Check everything with your multimeter before actually wiring it up if you’re not sure. You do have one and know how to use it, right?

That rating from that PSU will be the max it can supply, it is very unlikely that a consumer router is pulling 5A.

Your router firmware might even expose its power consumption if you are lucky.

I have the same/similar setup. My wall-warts are just plugged into the UPS.

I was just thinking the same thing. I was also thinking you can get a wide input voltage buck converter on amazon for cheap and use a bunch of cells in series as the UPS and the buck converter spits out 12V until it cant anymore. Then just wire up a charge controller to charge and balance your lead acid cells.

If you are using a buck converter you might as well use a ups. They’re both going to be ~ 95%.

Yea, small business routers (think old Cisco boxes) use a 5A laptop-style power supply. I suspect this is what OP’s using, as I’ve never seen a consumer model with such power specs. Consumer stuff is built around the cheapest hardware they can get away with.

Thing is, I don’t doubt the Cisco box (or similar business units) may need that much juice at times. Put your hand over one that’s not connected but powered on and they get hot.

Stuff like that they really don’t care about power consumption during design, just capability.

Yes which is why i started building a custom 20 usbc 65w max per port box and was going to swap out all barrel pluga for matching voltage usbc receiver plugs but havent finished it yet. Not sure about battery or if i was going to add one to it

Sounds interesting, do you share the project progress somewhere?

How about a portable power station? Basically a huge mobile battery with AC input. Some can switch over on power failure like a UPS. Some has USB PD (get 12V DC with the right cable) or car lighter socket (12V DC) or direct 12V DC output.

I’m talking about these, just a random article from my search:

https://techwriteredc.com/best-portable-power-stations/

If you’re going this route, you may want to pay attention to the switchover time. For most consumer hardware, it can handle 10-20ms of switchover time. However, enterprise grade stuff is more sensitive to power fluctuations and sometimes needs near instantaneous switchover. It can get very expensive if you want LiFePo4 (like many of these portable stations) while also being “on line” (meaning instant switchover).

There are middle ground options which have switchover timing of 5-8ms that are also LiFePo4. LiFePo4 is great because the chemistry doesn’t have a huge fire risk and it can do more cycles than a lead acid battery.

Anyway, my bad for rambling.

The common solution is not to replace the UPS but only the battery inside. They are standard sizes and for a cheap UPS probably around 10 - 20 bucks.

THIS! Normally, the battery should be accessible via some door or a few screws. Replace the battery for a few bucks and you’ll have 5 more years of peace.

This. My ups died after 10 years powering router and network. A replacement was $300 (for similar model) but the batteries were only $80. Just had to untape the pack and plastic adapter and transfer it over to the new battery set

Since it happens to be 12 volts to your router and many UPS batteries are 12 volts… Why not just tap the two leads coming off the UPS battery and run that to the router? After you buy a replacement battery of course, they really are cheap and easy to swap.

When charging, 12V lead acid batteries have significant higher voltages (>14V), so you basically need a DC to DC converter to make sure you get a stable 12V supply. Some (typically industrial/automotive grade) systems have that built into their internal power supply and can work directly off a 12V battery, but with consumer routers I would assume that not to be the case.

Hey, I have a lot of appreciation for the infrastructure you maintain so don’t take this the wrong way: you’re very confidently overcomplicating this one all over the thread. People run nominal 12v stuff direct from battery all the time and it’s fine. It’s the norm in RVs, boats, and off-grid housing. There’s usually quite a bit of wiggle room. The router I’m using right now won’t actually cut out until ~8v and sees almost 16 during my ancient lead acid battery’s eq cycles. It’s completely fine and has been for years. Not industrial or automotive grade by any means, a low-end Netgear from the thrift store.

You also state “while there is DC power the battery in a UPS isn’t used”. Assuming you mean AC that’s still not quite correct, it’s always being charged at least a little and tapping it for DC is perfectly fine.

That’s my advice to op, and a setup I’ve run before: replace the 12v battery attached to their existing UPS and wire the router/any other 12v devices right to it. A UPS is just a nicely packaged battery charger/inverter/transfer switch. Wiring them to larger/cheaper batteries that don’t happen to fit their casings is also entirely viable, as is running either of their outputs to a load panel. Sky’s the limit :)

Right AC. Was a typo, corrected now.

As for running nominally 12V stuff directly of a battery… you got lucky with your router then. I had the same idea with various mini PCs and ARM SBCs, and the majority absolutely should not be run directly off a battery where the voltage fluctuates so much. And it gets even worse when you try to solar charge the batteries.

I haven’t had access to grid power in over 10 years and am pretty familiar with this stuff as part of day to day life. I do now have solar. Really don’t think me and everyone else I know have been getting this consistently “lucky” for this long across such a wide range of devices. The 11-15v a nominal 12v battery system normally experiences is not a huge amount of fluctuation, and I have yet to encounter a 12v device that couldn’t take it. On the contrary, I’ve tried much dumber stuff and gotten away with it. There’s a 9v piano keyboard and a 19v computer monitor wired straight into that same battery. The only time I’ve actually killed something is by reversing polarity. Voltage too low=won’t turn on, voltage too high=gets hot, and all these years of wiring up random scavengings to see what happens have taught me most gear is surprisingly tolerant/resilient

e: for SBC stuff, automotive USB charger makes a great 5v rail. My “homelab” was at one point a pi 3b and a 5v Buffalo wifi router running dd-wrt plugged into a cigarette lighter

Search for “router UPS”

For example there is one from APC “# APC Back-UPS Connect 12V DC 36W - CP12036LI”

If you search for “12V ups” there are several. However, most only go up to 2 Amps. Not sure what kind of monster router actually needs 5 Amps, though. Also, I believe those 12V UPSes don’t provide status information via USB. So, there’s no way to know when the battery backup is going to fail.

I would love to know how you found that one, so I can look one that supports 60 W (12 V 5A). If i search that model directly, i can find it on APC’s website, but no combination of search terms brings it up otherwise, not router ups, not laptop ups… All I’m getting are the standard ups models with 120 VAC outlets.

For me that was literally the first unsponsored Amazon find for the term “router UPS”

I mean, there are 12V native battery systems out there, stuff like vehicle stuff.

Assuming that the 12V power supply on the router is permissive enough to take a certain amount of variation, I imagine that you can probably just put a 12V deep-cycle battery on the thing on the thing and directly hook up a 12V charge controller in parallel.

I dunno whether there’s some sort of voltmeter that you can connect NUT up to.

Personally, my position is that if NextCloud or whatever can’t handle power loss without corrupting data, that’s a bug with NextCloud. I mean, sure, it might not be able to complete an operation if there’s power loss while it’s running, but that shouldn’t result in corrupt data.

What’s the underlying filesystem on a nextcloud server? ZFS? Or something else.

You can install nextcloud on any file system afaik. Mine is btrfs. But yes, I’ve had unrecoverable database corruption with power failure. It uses mariadb for the database.

How would you wire the barrel style adapter directly to the battery, and charge it at the same time?

Same way existing systems work. The charger just moves the voltage somewhat up above 12V. Under normal use, the battery drops slightly below 12V. You have the things that draw on the battery wired in parallel with the charger. That’s why I’m saying that the power supply on the device would need to be tolerant enough to handle a bit of a range.

An inverter’s power supply will be able to handle that range, but you’re saying that you don’t want the overhead from that. A DC power supply that’s tolerant of that range will also work.

EDIT: There are also gonna be 12V regulated DC input power supplies that you could externally insert.

searches

www.amazon.com/…/B081RG8XP5

DROK DC-DC converter input voltage range is DC 9~36V (12V); output voltage is DC 12V; output current is 5A; output power is 60W.

Conversion Efficiency: >90%

Would have to compare to the existing efficiency of your inverter and AC-to-DC power supply.

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Thank you, I think this is basically what I’m lookong for. I’ll just need to find an adapter from car outlet to the correct barrel adaptor.

EDIT the only thing that would improve it is a user-serviceable battery.

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It looks to me like you have to replace the whole $600 unit in 10 years rather than swapping out just the battery. I’d rather not generate that ewaste.

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While there is DC AC power the battery in a UPS isn’t used. It’s not a constant AC-DC-AC conversion, that conversion only happens when there is a power outage.

The problem is that lead-acid batteries are a really shitty technology with high self discharge rates and short overall life span (their only advantage is high burst capacity that’s good for starting motors).

I would look for 12V LiFePO4 batteries in a standard lead-acid form factor that are meant as drop in replacements. Those are somewhat more expensive (like 2-3x the price) but will likely last a quarter century or more.

I am currently using an interim solution where my solar inverter has an seperate emergeny power outlet that works even when power is cut. Sadly it doesn’t switch to battery fast enough (like half a second delay 😓) for it to work as a UPS directly. But in combination with some old regular UPS that have spend batteries that only last a few minutes it works ok. But yeah, not the most efficient option conversion wise, but solar power is free 🤷

I did that and it works well. The only problem is that when the battery goes to 0 on a long outage, the UPS can’t recharge it. I had to pull the battery, charge it with a lifepo4 charger, then reinstall.

Short outages are fine.

Probably best to use NUT to shut down the servers gracefully if the power outage is too long.

Thank you that is a great insight and may be what I do if I can’t find an elegant DC solution.

I did this once with a router. I just bought a 12V SLA battery (a UPS battery) and a car float charger (sometimes called a “battery maintainer”). The charger was always connected to the battery, so it was pumping about 13V into the router. The router could withstand it. It’s easy enough to get a voltage regulator if it’s an issue, but most hardware already does it to an extent. It was DC all the way.

If I want 5V, I get a car USB charger and stick it inline.

How did you wire the battery up to the router, with the car battery maintainer attached?

Something about this doesn’t seem right. An ordinary router shouldn’t be the power hungry device that breaks your UPS setup. I have 3 Lenovo M910Qs, an HP T640, a switch, an external USB SATA drive housing, and two MODEM/routers hooked up to a cheap Cyberpower UPS and it tells me I’m drawing about 100W and should run for over an hour.

I’m pretty sure that the UPS failed because the battery was 5 years old. The manual specifies needing to replace the battery every 3-5 years.

I double checked the router and the power supply (which is medium-big size) says 12V 5A, which comes out to 60 W

Acronyms, initialisms, abbreviations, contractions, and other phrases which expand to something larger, that I’ve seen in this thread:

Fewer Letters More Letters PSU Power Supply Unit PoE Power over Ethernet SATA Serial AT Attachment interface for mass storage SBC Single-Board Computer ZFS Solaris/Linux filesystem focusing on data integrity

5 acronyms in this thread; the most compressed thread commented on today has 10 acronyms.

[Thread #112 for this comm, first seen 25th Sep 2026, 15:20] [FAQ] [Full list] [Contact] [Source code]

I went the POE route, inject poe to the router and use a POE to DC jack extractor to power the router/modem. My Poe injector is behind my UPS so it will remain powered on.

A lot of the POE options I’ve seen seem to top out at 12V 2A, can POE deliver 12V 5A?

For example, when i look at thus one, it can do 48 V but only about 0.5A, to achieve 25 W. A lot of them seem to be like this. https://shop.poetexas.com/collections/poe-to-dc-power/products/gpoe-48v25w

This is my router: https://www.verizon.com/support/verizon-router-cr1000a/

Just replace the batteries in the ups. They are almost always standard lead acid batteries. Take a pic of the wiring, swap them out, and you’re good.

I can do this, just trying to optimize away some unnecessary power losses to get longer lifetime out of the batteries.

This probably isn’t too useful for you as they only have 24v and 54v models, but Ubiquiti used to make EdgePower UPSes. They have a http management interface that lets you monitor the power usage or power cycle the router if a ping stops responding, and etc. I installed one recently for a POE switch of mine.