Ultimate Battery Backup Mod

Unless your main workstation is a laptop, you’ve probably got a APC or similar battery backup kicking around. But have you ever thought of modifying it to make it a bit more useful? After all, it can be used as a useful DC power supply…

[The 8-Bit Guy] shows us how he modified his APC to include a voltage readout, and direct DC output jacks. As it turns out you can get a lot more battery life if you’re not using the built-in pesky AC/DC power inverter! Stick around after the break for a very informative video on how he did it.

Of course you don’t need to start off with a consumer uninterruptible power supply. We’ve seen DIY systems put together without breaking the bank.

[Thanks for the tip Keith!]

90 thoughts on “Ultimate Battery Backup Mod

  1. > “… you’ve probably got a APC or similar battery backup kicking around…”
    No I don’t. My power goes out at most once a year and then very briefly, why would I bother with an APC? I feel like the same goes for most of Europe.

      1. I live in US and I lose power maybe once a year. It almost always happen when I am not using computer so I never bothered with UPS. If I needed something from internet, my laptop comes with me to nearby McDonald’s for free wifi (and free electricity if needed)

        I do know parts of US experience frequent power failures. I remember a news article about one area of Flint, MI losing powers for a few hours every week. Been going on for a few years before Consumer Power finally figured out what was the problem and fixed it.

        1. At one time california was know for constant power issues too. No idea what areas are now in a bad state and how cal is doing, but it seems there are plenty of areas in the US where it’s not good.

          1. Los angeles here.
            I have about 20-30 clients I manage, at least one of them will have a less than one hour power event happen at least once a week. (There was an area of PV that would have several second drops in the power all the time, every day, but we don’t do much in that area any more)

            usually have an extended (4 hours plus) event happen about every 2-3 months.

            Battery backup is an absolute essential for all the computer systems we install.

        2. I lose power 5-10 times a year, sometimes more. I live in a rural area subject to lots of trees and drunks to take out the power lines, though. Plus I’m serviced partially by a hydroelectric dam that suffers badly in late winter and summer in terms of power output due to low precipitation.

        3. I live in the US and my UPS trips off on a weekly basis. And it’s not like I live in the middle of nowhere at the end of an old power line, either. I live in a new development (< 20 years old) in an urbal area with fully underground utilities.

        1. Do you live in Nothingeverhappenslandia? We get a very nasty storm at least once a year than can disrupt power from mater of seconds to hours depending on what got hit and how hard.

      2. Or a rental thing. Myself second apartment in college town had rather noisy lines, I’d get a trip every other week just for out of range voltage. Couldn’t convince the landlord, he was a general contractor and built the basement apartment I rented. Next apartment was circa 70s, section 8, same story. Never lost power in first place (got hit by a duracho in the second but got power back quick), just had mains that thought >140v was normal. Moved to a trailer to get out of college town, and the UPS kept myself phone charged during a nasty power outage with sub-freezing temperatures; so I could check the emergency notices every few hours to see if a shelter was available.

        Guess the tl;dr is that some of us use a UPS for power conditioning.

      3. A lot of the US is rural-ish compared to europe- Texas in particular can be pretty bad. Flash floods, tornadoes, thunderstorms, etc all happen on a fairly regular basis depending on the time of year, and the power can get knocked out once every month for a couple seconds if you’re unlucky.

    1. yeah until it DOES go out and you were just about to press ctrl-s. Or you’re running critical infrastructure, or servers, … etc
      I think we had maybe one or two very brief power outages here in the last decade or so (Belgium), yet i still use a UPS in my office. They’re dirt cheap these days, and once the battery dies you can just get a new one and re-purpose the old unit for mobile applications.

          1. Right – because now we have ‘The Cloud’!

            There are millions of businesses that run things as mundane as POS cash registers – adding a UPS so such a system shuts down cleanly when power goes out is not an out-dated idea, nor is the idea that file servers relied on by multiple users be able to shutdown cleanly.

            ‘The Cloud’ isn’t a magic solution that renders all prior technologies irrelevant. When I was a child we had huge data centers that ran multiple virtualized operating system images for hundreds if not thousands of networked users – we called them IBM mainframes.

          2. The cloud? Nah, just don’t build a “house of cards” system. I have seen more outage due to failure of UPS’ than I have seen prevented by it.

            It simply is fact that most IT guys build their data-centers like rube-goldberg machines..

      1. So now the HaD readerships are all IT managers at offices and serverparks?

        I clearly got the impression the suggestion was that everybody has an APC.
        After all, I don’t think they allow you to mod an APC at the office or a datacenter for shit ‘n giggles

    2. Once a year? I am deeply in envy. When I replaced the boiler a few years ago, I had o check that the new (high efficiency) unit doesn’t need manual reset after power loss, as many do.

      1. In europe they often use underground powerlines for the distribution and only use the large mast-based transport for the long distance distribution.
        I think all those poles and small transformers hanging from them the US seem to use all too often isn’t beneficial for being lightning-proof.

        But maybe it’s something else, just a guess.

        1. a lot of places in the US use the underground lines also and generally are fairly reliable. The pole based stuff does exist in places and they usually fail not from lightning but from trees and other things hitting the lines during a storm. That said when i lived in the south east even the underground lines couldn’t cope with the lightning sometimes. What would happen is that there’d be a few dozen close-by strikes that’d either raise the ground potential enough to cause problems (GFCI outlets would blow a lot if in use during that), or it’d induce current onto the lines themselves, lost a few network cards and switch ports that way.

        2. Sometimes issues with strung wires themselves, especially during hard storms– 120KPh winds with snow take their toll,– but much more due to animals and age of equipment. In the last year, at least three or four due to fluffy-tail rats in transformers (not too long each), one due to breaker failing at substation (about a half day out), and several short ones that self-cleared and I don’t know the cause. The first year I was in my house, total of about two weeks without power (yup, about 350hours). This isn’t rural, either. Just old gear that is undersized. System was designed for 50 or 60A service to house, and even a few 30A. More homes, all 100, 150 or 200A (the new standard here), and more businesses, without sufficient upgrade to the delivery gear.

    3. Hmm my power goes out last time 3 years ago. They did maintaince and notify 2 weeks earlier. I dont use APC ups any more because it cause more outages than we have in network. Btw that 60min run time… It is not because of battery. It is some kind safety feature at APC. I try put 200A battery and it still shut down at 60min

      1. I recently moved from NJ, where I had a ‘full house’ (minus A/C and Electric oven) generator that ran on natural gas cut-over automatically when the power went out. It was kind of expensive, but after using it for the 4-5 days we were without electricity because of superstorm Sandy, it was a great investment.

        The power used to go out a couple times a year, usually for no more than an hour or so, typically when either a storm or driver would damage the lines somewhere between my neighborhood with it’s underground power feeds and the generation station.


    4. So some people live in a no-lightning area? I find that hard to believe. Lightning that is close often puts pulses on the line or brown-outs the voltage for a few milliseconds. That can wreak havoc on a computer. The same is true for underground lines. I had a nearby lightning strike blow several small pinholes in the wire going to my 350 foot deep well.

    5. I’m in the UK and (as far as I can recall) only had one or two power cuts in the last decade, having said that the last one trashed enough stuff to make me wish I hadn’t been so cheap and bought an APC (I have one now by the way)

      1. “Trashed enough stuff”?

        I’ve consulted my UK American English-English dictionary, but I’m not quite sure what you mean by ‘trashed’ – do you mean reset clicks, lost settings, etc. or do you mean more permanent damage?

        In the U.S. when we have power interruptions they tend to be outages, not surges or something else, just a lot of clicks to reset, nothing serious.


  2. You would bother with one if you get a spike on the lines that can take out your computer. Do you have lightning around you ? You also would plug your DSL or cablemodem ethernet into it for isolation. Just in case of a surge. It’s fairly cheep insurance.

    1. I only had an incident with a surge due to lightning once in my life. And it wasn’t too severe, only killed one device.
      And so yes theoretically if you are obsessive you might want a surge protector, but then, there is a chance of a roof collapse too, and flooding, and of course fire. So a fireproof container might be an idea too, and make it able to float, and have a strong titanium case.

      Simple surge protectors are way way cheaper than a full APC too I have to add.

    2. Those small UPS units are false security when it comes to atmospheric discharge. They can suck few thousand kV short spikes, but if lightning strucks near you protection will explode into pieces and discharge will fry your equipment. Isolation transformer is much better device for protecting your stuff. And if you want to have good protection of your equipment that uses DSL line use two media converters and put optic fiber between your modem and LAN.

      1. Probably the media converters are more expensive than the modem it is supposed to protect itself.
        An isolation transformer is not so great in lightning protection. But there are quite big lightning arrestors (with spark gaps) to be mounted on the breaker board.
        Decent lightning protection is multi leveled: At the building entrance (big spark gaps for 10kA to 100kA), at the breaker board (smaller gas discharge tubes) and at the device or wall socket (varistors).

  3. He’s built this using a very small UPS – what is that, a single 7 amp battery?

    If you are going to invest that much time & effort, you should (at least in my opinion) start with a bigger battery.

        1. no it’s Ampere-hour.

          An ampere-hour or amp-hour (SI symbol A. · h or A h; also denoted Ah) is a unit of electric charge, equal to the charge transferred by a steady current of one ampere flowing for one hour, or 3600 coulombs.

          1. I know it’s ampere (as you could have noticed if you read the comment lower down first), I used the capital because it originates in a name, and it was a joke which is what the smiley was all about..

            But I might add that ‘amp’ is even in the Oxford dictionary as a seemingly acceptable short form. Although I’d say A or ampere is better for a serious comment IMHO.

          2. You’re both wrong.

            A unit of charge is coulomb (See whatis.techtarget.com/definition/coulomb ).
            Amp Hr is a measure of battery capacity.
            Amp is a measure of current (which is 1 coulomb/second).

      1. >> He’s built this using a very small UPS – what is that,
        >> a single 7 amp battery? If you are going to invest that
        >> much time & effort, you should (at least in my opinion)
        >> start with a bigger battery.

        > the unit of electrical charge is not “amp”.

        No, it’s how most people indicate the capacity of a
        *battery*, as in “a single 7 amp battery”. How DSP *you* describe 12V SLA batteries as used in the APC unit? Size? Color?

          1. He would obviously use Ampere, which is the actual word for with amp is the short form.

            “The ampere (SI unit symbol: A), often shortened to “amp”, is the SI unit of electric current (dimension symbol: I) and is one of the seven SI base units. It is named after André-Marie Ampère (1775–1836), French mathematician and physicist, considered the father of electrodynamics.”

  4. I haven’t tried that but I did look into this, https://www.teslamotors.com/powerwall but then some research lab discovered how to make the batteries last so many more cycles that the power wall now looks like a waste of money and I’d be better of waiting a few more years. So that would be perhaps 2 or 3 more short outages to endure, and I can live with that.

    1. There have been announcement of new wonder batteries every 2 months for the last 2 or 3 decades at least And we are still waiting.
      So I’d advise you to not hold your breath.

      1. Well, batteries have been pretty improved for the last 2 or 3 decades, it’s just that the power-hungriness of our devices is increasing faster than improvement on batteries.

        1. The improve steadily in modest increments, rather than one of those wonder inventions making all other types obsolete.
          Although we did hit somewhat of a wall or at least a hill lately I think.

  5. Here in my neck of Arlington, Virginia, we get serious flickers almost every time we have a thunderstorm (frequently), and lose power (with a huge BANG! from the nearby substation which floods) a couple of times a year. After losing way too much data over the years while counting on el cheapo UPSs (APC, I’m looking at ????????????), last year I bought a couple of very nice ones that painlessly take my rather large collection of equipment through stroboscopic power events. ???????? UPS? No way!

    1. There’s certainly nothing wrong with using such if your area is less than perfect.
      And there can be some real excuses why an area is less than sterling. Every area in the world has something not working right, some parts of the world have power issues others have constant flooding for instance, yet others can’t get a system of public transport running in an acceptable way.

      But the author is still mistaken if he thinks the whole modern world is in need of them and has them in massive use.

    2. I have never quite understood the southern region of the US (or the dust bowl for that matter)

      “Oh hey, [Insert natural disaster here] destroyed this thing. Let’s build it in exactly the same spot, in exactly the same way.”

      1. I guess it also might be about the space being available and the planning permits being all done already.
        Although that’s less of an issue in areas where there is plenty of room and locations though.

        And then there’s the environment and existing infrastructure.
        For instance if the soil is all rock you can’t put the cables underground (without insane expenditure). And then there are places that flood a lot or with tectonic activity of mudslides and all that.
        And for power (and a few other things) you also need to put things in a place where the main distribution lines can be routed to of course.

        Not that there isn’t stupidity too.

  6. I’ve been finding lots of 12V-only UPSes in thrift stores for $5 and less, all their batteries were dead but I was able to revive every single one just by adding water and charging them on a pulse charger (desulphator). No idea what their original use was, but now I use them for the lights around the house (12V led strips)

    1. They might be for backing up broadband gateways with integrated VoIP to provide phone service during an outage. From what I understand AT&T charges end users for replacement of the UPS when the self-test decides it’s too old and starts beeping incessantly in the middle of the night. AT&T doesn’t take them back, so some fraction makes their way to the thrift store.

      I have a Belkin-branded box from an old AT&T gateway that I replaced the barrel on to fit my home NAS.

      1. I once visited a telephone company switching center and got a chance to see their battery room – racks upon rack, rows upon rows, of open top batteries. They were wet cells with no tops, in glass tanks that were about 18-24″ square and about 30-36″ tall… I was told that the used tanks made great aquariums.

      2. They are SLA, but “sealed” is more like the “No user serviceable parts inside” warning. There is always a thin plastic cover barely glued down either over the whole of the battery top, or individual circle covers per cell. Pop the cover(s) off and each cell then has a little round rubber cap on it. Just slide those off and add distilled water until you can see the glass mats glistening, cycle charge the batteries as a whole a few times in desulphate mode and many times I have a near-full capacity battery again.
        You’ll need to cycle them without the rubber caps on at first as they will need to vent after having been topped off and they will tend to launch, but you can push them down and glue (I just tape) the plastic cover on after all that.

  7. I did these mods years ago… 3 and four digit volt meter are cheap from Schenzhen. I also add them to my motorbikes and cars. You can tell a lot about your charge level from the voltage, and if your alternator is working. And that APC he shows is not a good unit… it’s a tiny one battery unit. My units have four of those batteries in them… or even better, one of mine has a car battery. It’s old school from the early 80s and the car battery one is the best.

    1. most car batteries aren’t the best choice. ideally you’d want a battery that can handle deep discharge. most average car batteries are more focused on delivering a huge starting current and having a modest reserve capacity.

  8. Careful! Many cheap UPS with an *internal* battery do not have AC isolated from the battery! That is to say that the battery has 12V across it, but with respect to ground, you will find + or – 60V on the terminals. The battery being inside the plastic case is insulated from you touching it. Do this mod, or attach a larger external battery and you have to keep those terminals insulated. Attach a ham radio to it or anything that can make contact with ground, and you have a shocking experience. The UPS in this video might be OK due to the large, magnetic transformer. I have a switch mode UPS with this 60V exposure. Measure the battery terminal (or DC) to ground with your DVM to find out if you are at risk.

    1. Indeed! I have seen UPSes where the battery is directly connected to one of the AC lines. In many European countries (with reversible Schuko plug), it means the battery may be connected directly to 230 V live voltage or to the 0 V neutral, depending on which way you plug it in the wall outlet.

      Even if the UPS has an isolating transformer, the isolation is probably functional only i.e. it doesn’t fulfill the requirements that are needed between line voltage and touchable parts. The battery and other internals are not touchable without this hack, consequently the manufacturer may have selected a lightweight insulation. The poor insulation of the transformer can be confirmed if the data (USB/RS-232) port has obvious isolating components, like optos, as it indicates that the manufacturer doesn’t rely on the main transformer isolation alone. On the other hand, if the data port (USB shield or RS-232 pin 5) has a direct connection to the battery circuits (can be verified with an ohmmeter), the main transformer is most likely well insulated, having a reinforced insulation as the standards call it.

  9. What I want is a way to integrate the UPS into the PSU of a PC. Since most of the time, UPSs are used to back up computer hardware, i tend to wonder why it hasn’t been done yet.

    I would hack something like that together myself, but I don’t want to risk any of my current hardware in testing. Money is one of my most limited resources.

    1. Take a look at something like a pico-PSU, modern computers draw most power from the 12V line, the rest can be done with buck converts without loosing too much power…
      The only problem being is that if you do this, the battery that would fit into a 5.25” bay has be able to source full power+converter losses, SLA is not up to the task here.
      I remember seeing some custom-made motherboards google was showing off, it had all the electronics integrated and they just connected a 12V/7Ah SLA battery. THAT I would want.

    2. What I want is a way to integrate the UPS into the PSU of a PC. Since most of the time, UPSs are used to back up computer hardware, i tend to wonder why it hasn’t been done yet.

      This is what Google does in their custom-designed servers – they put a small battery in the server blade, good for a short period (10-15 min?). Many small batteries are more affordable than several massive batteries.

      Also, this is how nearly every laptop is built… ;^)

      1. You would be shocked at the size of battery systems and UPS systems used to back up the “cloud” data centers, do you know what mega watts are? Try 100’s of mega watts in some cloud data centers. The problem with the Google methodology is all batteries require periodic replacement – and are subject to failure. If its parallel for voltage or series for capacity you can get bitten…literally 100’s of thousands of batteries if scaled as Google does in the data center. Managing battery maintenance has to be a nightmare….. There is no such animal as a maintenance free battery, thats a battery industry marketing term for VRLA’s..its smoke & mirror’s. “Its easier to fool people, than it is to convince them that they have been fooled” Mark Twain

        Yes, the smaller white wires he used will smoke, as well as will his jacks if there’s a fault in his connected equipment neither his wires or connected equipment can handle the short-circuit current of that little 7.2AH battery. It can deliver about 130A for 5 seconds to a bolted short-circuit. Even if its not a bolted fault, it could burn down the house. Bolted fault means a zero impedance fault..Yes, batteries are rated in AH, not ampere’s, except for short circuit. They deliver varying runtimes for varying load amperes. We have a fuse inline with the red wire, and its sized to protect the wire and support the load rating.

        Guess what? The UL Listing or CE has been voided, as has the warranty by hacking this product and your insurance company will not likely pay for any damages, even if your house burns down! I know, I work for Schneider Electric, we make that product and I’m a real electrical engineer, not a hacker! This hack is plain stupid!

        1. “100’s of thousands of batteries if scaled as Google does in the data center. Managing battery maintenance has to be a nightmare…..”

          The servers themselves are expendable, they die in-place and Google leaves them there until a sufficient number fail, but by then the cost has been written off and the servers are replaced en masse.

          If the battery lasted 4 years, that’s enough. If the server can run after the battery dies, so much the better. A 7 AH battery retails for $20 near me, buying them by the pallet must drive the cost down, making the investment an easier decision.


  10. Yes, Tony Kay, I too was going to say, BE CAREFUL! I’ve a couple of UPSs that are not isolated from the mains. Doing this mod would make a death trap.
    Choppergirl has a good idea too. I’ve had UPSs that can be got for nothing as they have a dead battery, and then hooked them onto a car battery. This increases the run time enormously.

  11. All you folks who seem to feel nothing bad will happen to the power grid, or other daily modern conveniences will no doubt be the first to cry like little biiiatches when a SHTF scenario happens. One need look no further than the fallout from major weather events that take out infrastructure (water mains, electric power, public transportation on strike, etc). What happens? The un-prepared scurry like little frightened rodents with no plan. They will be doomed. Waiting in lines for meager rations of water or other provisions. Fighting among themselves for whatever scraps of sustenance they can forage for.

    Plenty of pictures of desperate people queued up at aid stations (where food/water rations are handed out).

    So yeah, all you fools who think the “gubmint” will take care of you, keep on believing it. Meanwhile the preppers among us will be laughing at you (and/or shooting your ass if you try to take what I have by force).

    The story of the Ant and Grasshopper is worth remembering.

    1. You should face your fear and just press that comma and period button when the time comes.
      And while you are on a roll maybe an apostrophe once in a while so you can say things like “I’ve”?

      Just tossing it out there. Take it or leave it.

  12. It must be a slow weekend at Hack-A-Day.

    Yesterday, “Colin Furze Gets Burned” – 3 years ago. Check the post date on the You tube video.

    Today, it’s “Ultimate Battery Backup Mod” – from a year ago. Not that it’s much of a hack….

  13. I love you UPS hack of a original APC. Have used lots of them over the last 20 years when I had my business in Europe. Now I am living in the midst of the rain forest and I was wondering or there is a way to connect several 12 volt car battery’s I have sitting around in line with the battery inside the UPS. In that way I could create a much bigger UPS that can deliver even more backup power. Is this possible and are there any limits to this. I love to make use of the already very sweet electronics these APC machines include to create a even bigger one.
    Thanks mate, Ro

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