Dead UPS Batteries? There’s a Cheaper Way! 82

Replacement UPS BatteriesThe concept of “planned obsolescence” is nowhere more visible than in the battery backup (or UPS – Uninterrupted Power Supply) market. With the insane prices the manufacturers charge for batteries, it’s easy to compare it to the video game console industry: the companies must barely break even (or maybe even lose money) on the hardware… but what goes inside makes all the money. But that’s not the case. The large UPS companies like 600 lb gorilla American Power Conversion (more commonly known as APC), make plenty of money on the units, and then make even more money on the “consumable” battery packs — as you’ll see from their overall marketing approach.

Your UPS Unit is Dead? Probably Not

Let’s take the UPS unit that is probably sitting under your desk right now. When it stops working, regardless of whether or not you get an error message, there’s a 90% chance that fresh batteries will fix the problem. Getting a battery warning light is, of course, an obvious indicator. But I had an APC Back-UPS XS 1500 LCD fritz on me recently, shutting down in the middle of the day without any warning. It just sat there beeping and flashing “F01” on the LCD screen. A quick web search revealed that meant the unit was overloaded… which came as a surprise since I’ve been running the exact same load on this unit since I bought it 5 years ago. I knew what would happen if I called APC’s tech support number (as I’d done it many time before), but I figured I’d do it again, just for fun. 🙂

  • That specific error code means the unit is shot and that replacement batteries won’t fix it? Check!
  • Current unit is past its two year warranty? Check!
  • You’ll let me trade in (they call it “trade-ups”) this unit by sending it back to you for a small discount on a newer model at retail price, even though I could just purchase that newer unit outright for less at a local store? Check!
  • I decline politely, hang up the phone, and curse you under my breath? Check!

So rather than junk a UPS unit that I really liked, let’s assume I’m willing to roll the dice and try replacing the batteries anyway. The next step would be a trip to APC’s replacement battery look-up tool… although that’s not what it’s called. They call it their UPS Upgrade Selector. That’s right – they’re assuming you’re going to upgrade the unit rather than replace the batteries. In fact, the text at the top of that page says:

APC provides upgrade options and battery replacement solutions for both In-Warranty and Out-of-Warranty UPS products. Please enter your existing product information below to view recommended options.

Again: the upgrade option is pitched before battery replacement, even though 9 times out of 10, a replacement battery is all you need.

A Little Homework Goes A Long Way

The model for my UPS is BX1500LCD. Just for fun, go ahead and type that in the Upgrade Selector page to see the results. Again, a hard pitch showing my two options, with the words “Recommended Solution” in bold in the “Special Notes” section under the trade-in option, along with a comparison matrix showing why trading in is clearly the way to go. Buried deep in the pitch, however, is a link to the replacement battery: an RBC109. So let’s click the link to the RBC109 page.

A replacement RBC109 battery pack costs $79.99. But the picture on APC’s own site reveals a few interesting details that may not be obvious at first glance. Here’s the photo direct from their site:

APC RBC109 Battery Pack

APC RBC109 Battery Pack

The most obvious detail is that the RBC109 is actually two identical batteries, with a short cable linking the positive terminal on one to the negative terminal on the other (called being wired “in series”). Just as it does when you put multiple batteries in any device with positive connected to negative (like when you stack batteries in a flashlight), the voltage increases to the sum of each battery’s voltage (two 6V batteries in series would be 12V), so chaining batteries like this can support a larger load. But exactly what type of load? What’s the voltage of this battery pack? What’s the amp-hours rating? Good luck finding out from APC. If you look really hard, you can see listed under “Volt-Amp-Hour Capacity” a number 9. Voltage is nowhere. But you’ll get plenty of data on the net weight, height, depth, operating temperature, etc. You’ll also see that even though the “expected battery life” is 3-5 years, they only warranty their batteries for one year. 🙂

As with all multi-battery packs, the APC RBC109 is made up of batteries they sell individually. In this case, the RBC2.


APC RBC2 Battery

Look familiar? It should. The RBC2 page shows a retail price of $44.99 (so at least you were getting a bit of a deal on the two-pack), but it doesn’t show any voltage or amp-hours on the page. So once again, it’s a mystery battery!

Uncovering the Cover Up

Which brings us back to the second detail I noticed in the RBC109 battery. Scroll back up and take another look. See the APC label? It’s covering up the printing on the side of the battery (the APC marketing department got a little smarter and PhotoShopped it out on the RBC2 image). What’s the label covering up? The label’s covering up the fact that there is a cover up! APC doesn’t make their own batteries. True truth is that there’s only a handful of factories in the world (all of them in Taiwan) that make these rechargeable sealed lead-acid batteries, which power a wide variety of devices, including powered wheelchairs and scooters, alarm systems, and battery backup units. There is very little (if any) difference in quality among these large manufacturers, meaning all you need to care about is the voltage, amp-hours rating, and physical dimensions of the battery, and you’re good to go… at a much cheaper price than buying the mystery batteries straight from APC.

Going back to my Back-UPS XS 1500 LCD, we’ve already established that it takes an RBC109, which is actually just two RBC2s, which is actually just a 12 volt 9 amp-hours battery. If you search on eBay for “1290 battery” you’ll get plenty of options. Click here to give it a try.

It really doesn’t matter which seller you use, provided they have a good reputation (I look for “Top Rated Plus” sellers). To replace an RBC2, it’s also possible to purchase a 1280 battery, which is the same dimension and voltage, but with a slightly lower 8 amp-hours rating. But for most battery backup applications, they’ll still work fine, although you’ll lose a few minutes of runtime. In my case, that’s not a big deal, since my UPS batteries only need to work for a matter of seconds until the generator kicks in and takes over. You can purchase two 1280 batteries for $33 (with free shipping). That’s $12 cheaper than buying only one of the exact same batteries from APC… with the shiny sticker. That’s a pretty expensive sticker!

The More The Merrier

Larger battery backup units are no different. I have some rack-mounted APC Smart-UPS units that call for an APC RBC24 — at a whopping $349.99! Here’s what $349.99 worth of batteries looks like:


APC RBC24. Anything look familiar?

Yep – you guessed it. It’s four RBC2 batteries tucked neatly in a metal frame with a fancy yellow connector. But if your UPS needs an RBC24, where are you going to get a metal frame and fancy connector? You already have one — it’s inside your UPS! So when it came time to replace the batteries in my Smart-UPS 1400 RM 2U, I bought four 1280 batteries on eBay for $60, removed the old battery tray from my UPS, took out the old batteries (I recommend using your smart phone’s camera to take photos of how all the batteries connect together as you take them apart), put in the replacements, and fired it up — saving $289.99.

I have five APC S20BLK A/V battery backup units at my house. I love them – they’re battery backup units that are designed for audio-visual components, with built-in network adapters to communicate and broadcast their status. I picked them up from a computer recycling company for cheap, but most of them needed replacement batteries. This time, APC calls for an RBC63. But when I checked their RBC63 page, I got nervous. Here’s what that battery pack looks like:


APC’s replacement battery pack for an S20BLK: the RBC63

And when the price on their website is only listed as “Contact Sales,” you know you’re not going to like the answer. I was able to find an APC branded replacement online for $308.94 with tax and shipping.

But after removing a battery pack from one of my S20BLK units and opening it with a screwdriver, I saw that it’s simply four RBC2 batteries tucked inside and wired together. Another $60 on eBay, and I had a brand new battery pack, saving almost $250.

But Wait! There’s MORE!

In homage to the great infomercials of the past, I’m leaving the biggest money saver until the end. And here it is: if you have a UPS that takes multiple batteries, chances are than when the battery pack fails, not all of the batteries are bad, and you don’t have to replace all of them! When the batteries are wired in series (as we’ve established they are in UPS units), it only takes one truly “dead” battery (meaning it can’t pass any current along) to make the entire array unable to provide power.

So whenever I remove multiple old batteries from a UPS, the first thing I do is shake them individually. If they rattle, they’re dead. Go ahead and toss recycle them (in fact, some battery stores will pay you for your dead RBC-style batteries). If they pass the shake test, I connect them to one of my CTEK 12 volt battery chargers (any car charger will do – car batteries are also 12 volts). If my charger doesn’t light up, it means the battery’s posts aren’t connected internally, and so the battery is dead. If the charger’s lights rapidly switch between “fully charged” and “charging,” then something’s wonky inside the battery, and it’s dead. But if it charges, and stays charged, put it in the “good” pile.

In fact, I was able to salvage two good 1280 batteries while replacing a dead array on a UPS unit last week, and then put those two in the Back-UPS XS 1500 unit that the APC tech support rep had informed me was “dead” because of the F01 error message it was flashing. My “reclaimed” batteries did the trick, and it’s now once again powering the desktop on which I’m typing this article!

Bottom Line

So the bottom line of this blog post is: don’t throw away your money like you throw away old batteries. With a little web searching and some eBay shopping, you can buy the exact same batteries the big boys are selling (like APC, TrippLite, and all the others), made by the exact same skillful Chinese hands, in the exact same dimly-lit Taiwanese factories, for way less money.

Questions, comments, or stories of how you able to replace your UPS batteries on the cheap? Leave them below!

  • Mike Craft

    Yet another great post, thanks Steve! I have UPS’es EVERYWHERE in my house, most take RBC07’s, and I have been purchasing the off brand from eBay for a while, but I also have some APC 1500VA A/V units I picked up from Best Buy for $99 on clearance, which I was really nervous about after looking at the batteries, now I am not :). I should have know after a few screws it would be the same old thing!

    • Eric Jordan

      After reading your section here, I went to E-Bay, and purchased (4) RBC109 battieries, or the like, for a whopping $18.50 each!!! CHEAP, HUH?? This also included….get this….FREE SHIPPING!!!!
      My work place had actually thrown away (2) APC 1500RS UPS units, and when I saw them in the trash, I asked if I could have the units. Of course, they said yes, since one mans trash is another mans treasure!! Believe it or not, the only problem with the units was that they were over 3 years old, with dead batteries!!! So, for $74.00, I was able to bring these “thrown away” UPS units back to life with your help!!
      I already had a APC 1500 Pro 1500 on my PC, but after replacing the batteries for $18.50 ea, I was able to take the “thrown away” units, and place one on my home entertainment center (for the DTV receiver to keep power, in case of an outage), and the other one went on my (2) Fluval 406 canister filters on my 180 gallon aquarium!!! talk about a $420.00 savings!!!! Thanks for the info!!!!!

  • Tex

    Steve, great article. I’ve been in electronics for more years than I’ll admit to, so I just naturally did what you did with my UPS. I only have a couple of little comments on your procedure with using the “good” battery(ies) out of a set. All of the batteries are the same age, so there’s a good chance that a “good” one will also go “bad” shortly if you keep using it. Also, I put a date tag on every battery to keep track of the “good” ones that I keep.

  • Jamma

    Great article, thanks. We’ve got a (pretty new) APC at the company – so I’ll hopefully remember your article when they start to fail. 😀

    It surprised me that you’ve got several UPSes at your home (plus a generator) – I live in Germany and *nobody* has UPSes at home (except maybe some crazy hackers 😉 for their computing facilities in the basement). Is power supply so shaky over there?

    • It’s not so much that power is shaky here, it’s more that I hate rebooting equipment, and I like the protection from surges and brownouts that UPS devices provide.

  • Peter Harris

    Steve, interesting article with good information about the APC batteries, but your wording is misleading when you discuss the difference between series and parallel connections.

    In fact, the voltage does *not* remain the same when the batteries are in series. *Putting them in series adds the voltages of the component cells together.* That is, four cells of 1.5v in series will have an output voltage of 6.0 v. The series connection increases the voltage, not the capacity. Those same four 1.5v cells wired in parallel will have an output voltage of 1.5v but four times the capacity of a single 1.5v cell.

    Just use any search engine and look for “series parallel battery connection” (but leave off the quotes) for quite a few sites that will verify what I’ve said.

    • Right you are, Peter — and thanks for the correction. Parallel is wiring positive to positive and negative to negative, which would increase capacity at the original voltage. Series is positive of one battery to negative on the other, doubling the voltage at the original capacity. The unit in this case is indeed wired in series, and therefore is running at 24V. I’ve updated the article. Thanks!

  • mark

    Several comments: the first thing you do is, on the APC (or whatever) site, is to look up your battery, and see what RBC is in it. Then you go online, to a battery reseller, as Steve did, and search for RBCwhatever. Most resellers will have it by that id.

    Second, no, they’re not all in Taiwan; some are in China, some in Vietnam, there may even be some in the US.

    Third, and this is *very* important, if you’re running serious UPS – that is, a rackmount for servers, UNDER NO CIRCUMSTANCES let them tell you what will work: ONLY HR – high rate – rated batteries will work. Otherwise, the little red LED that says “Replace Battery Now!!!” will never go off. The price should be about the same.

  • Larry

    Here is one thing to look out for……….. On older UPS’s the charging voltage can “vary” with age usually going up. I had 7 Smartups 700’s that began cooking the replacement batteries. After some research I found a site that explained the charging circuit and how even a slight increase in charging voltage can quicly overcharge the batteries causing them to overheat, swell and quit working. After I tested the UPS’s I found that all 7 were over 1 volt higher explaining how my batteries were dying in less than a year. Now….these UPS’s were from the mid 90’s so I felt like I got my fair, second hand use out of them so they hit the electronic recycle bin at the landfill. Also, I’m not saying that everyone should be checking the charging voltage of their UPS’s. If you happen to replace the batteries and after a short period of time they “cook” you may want to consider a test. Unfortunantly there was no adjustment on the 700’s like turning a pot inside so the only choice was to get rid of them.

    Great article Steve!!!!

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  • Great article. Thanks a lot for the good information!

  • marcia

    My APC SMART UPS 1500 is 8 yrs old (2005). Not sure how long their life expectancy is. In this instance, would you still recommend buying replacement batteries, considering the age?

    • Hey, Marcia. Are you talking about the life expectancy of the UPS unit or the batteries? The UPS unit should work for a LONG time. I’ve got lots of 2005 and older units in service, and they run like champs. So if that’s your question, then yes – new batteries will breath new life into that unit at a far lower cost than replacing the entire thing.

    • lsatenstein

      Yes, Change the battery or buy a large external car battery and jigger it in.

      The electronics in a UPS is usually good for up to 20 years. What I did was purchase a 200 amp hour car battery. I have a plastic container from Walmart, in which the container has the car battery side by side with the UPS. You should use 14gauge house wire with clips( hardware store) to match the existing battery clips.

  • Deron G

    Great article! Hoping that my $37.95 batteries off eBay do the trick for me. Thanks for sharing your experience and knowledge, Steve!

  • eric

    Comment: Dear Steve, i have a 1000 VA UPS with 1 8A battery inside. the local elec store here sells 7A and 9A UPS replacement batteries. I am wondering if both or either one of these will work for my machine given the amperage differences? many tnx, Eric

    • Either will work, but the 9A will work better! 🙂

  • Danica

    Whenever there is interruption on power supply, it is best to utilize battery back up to maintain using your gadget or any electric stuff. I would love to read more reviews from you about this UPS before I decided to buy one.

    • Hi, Danica. So… you’d LOVE to read more reviews about UPS units BEFORE you buy one? Is that why the URL you posted in your comment linked to a site that sells UPS units in Romania? Don’t worry – I removed the spammy URL before allowing your comment to appear. 🙂

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  • Ryan

    Hey Steve, it appears our backup is ‘overloaded’ as you stated in the blog. This machine is only 2 years old unfortunately. It explains why we’ve been having connection issues with our server the past week. My question is, do you know how long this current machine will last as a surge protector until our replacement arrives? Thanks for the insight!

    • It really depends on whether or not you have any power outages in the period of time it takes for the replacement to arrive! Sometimes the system will run OK in “overload” mode, but it will try to shut down your system immediately if you’re running any automated shutdown software (like I am). I’ll be crossing my fingers for you. 🙂

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  • Jeff

    Steve, I’m trying to determine if the batteries in my XS 1500LCD are bad or the unit itself. It is used in a work environment and I was called to troubleshoot why the equipment the UPS was connected to wasn’t powered on. The UPS showed 118V incoming power but 0V was going to the battery backup outlets, as verified with a Fluke. The surge protection outlets work fine, 118VAC output through them.

    The batteries inside the UPS have a date on them that say they were replaced less than 18 months ago. Shouldn’t batteries last longer than that? They are PowerSonic PS-1290 batteries.

    • Hey, Jeff. The PowerSonics are decent batteries in my experience, so yes.. they should last longer than 18 months, provided they’re not being cooked (overcharged) by the unit. But if nothing’s coming out of the protected outlets, then I suspect something is disconnected inside one of the batteries — and it’s possible that one of the batteries was just defective when you got it (or burned out too quickly).

      I’d try yanking the batteries and testing them each individually, and seeing if they will take a charge from a low amperage 12V charger (like the CTEK units I’ve reviewed).

      I bet one of the batteries rattles when you shake it, meaning something is physically disconnected inside. Replace that battery, and you should be good to go.

  • Con K

    Great article. I’ve also been doing my own replacement batteries on our APC UPS’s for many years now. Actually bought one from APC a long long time ago, and after I replaced it into the UPS I pulled apart the old battery pack and was laughing/crying at how much I’d paid for the contents.
    At work I have 4 x 1500VA towers, and 2 x 3000VA Rack Mounts. The replacement pack for the 3000VA Rack Mounts is over $600. This actually contains 8 x 6volt SLA batteries which you can get for approx $45 each = $360, so it’s a hell of alot cheaper to do it this way.
    One area I disagree with the article is battey quality. Most SLA batteries are the same, except for Yuasa. Yuasa are significantly better than any other SLA battery, The original batteries used to last us about 3 – 3.5yrs, but with a Yuasa replacement we are now seeing 5yrs+ before we need to replace them. Yes, they are more expensive than other brands, but they are worth it.
    Note in a previous life I worked for a company that made Grade 4 Alarm Panels (these are what Banks, Armoured Car companies, Gun Shops and other high value / high risk premises use). Our spec only allowed the use of Yuasa SLA batteries due to their better preformance.
    Try them, you won’t be dissapointed.

    • Thanks, Con. That’s great feedback. Maybe the Yuasa batteries will be better in a UPC than they are in a Sea Doo, since the OEM Sea Doo batteries that Yuasa provides to BRP are absolute junk, and require replacement every 1-2 years. I’ve gone with AGM batteries for my boats, and would love to see AGM technology make its way to the battery backup units eventually. It’s much better tech than sealed acid! 🙂

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  • Will

    Ok this seems to be a good place to ask this question. I do not understand the difference in these two ups. could someone explain why one cost 3 or 4 times more than the other in detail. they are with in 100va of each other and the larger one has 4 batteries instead of 2. I just don’t under stand the cost difference The top link could be found for 150$ the bottom one ran about 1000$

    • Hi, Will. The BackUPS unit (first one) will only let you manage it from a machine to which it is physically connected via a USB cable, and can only shut down that one system. It’s designed for single workstation applications. The SmartUPS unit (the second one) will accept a Network Management Card (NMC), which allows that UPS to be managed over the network via SNMP or Web, as well as allow it to communicate with any number of servers on your network and shut them down via PCNS. You can also “hot swap” batteries in the unit without taking it offline. It’s designed for server locations, and all those extra features are why it’s more expensive.

      • Will

        wow thanks for the super fast response. so the cost is really just added for remote management and multiple system shut down. its not due to say sine way output or any power input/output? I understand that 4 batt are going to provide a little longer run time but the cost difference just amazes me. not to mention the nmc is an added cost. i had always assumed it must be some other reason not just the mentioned management upgrade

        • Hey, Will. The BackUPS does a “stepped approximation” of a sine wave, while the SmartUPS do true sine wave (the difference should only technically be an issue when running a motor). The SmartUPS also claim to be engineered to last longer. The main differences are that one is a product aimed primarily at the residential market (BackUPS) and the other is the commercial market (SmartUPS).

  • Jesse

    Hi mate great read that

    just thort id mention somthing iv found amuzing for the last few years. I worked in the alarm industry and if theres a battery failure you straight out always just chuck the old one and put in new. no testing is ever done .. well it was discouraged due to well needing to make money.

    then I being someone who has a great time messing with electrical eqipment one day cracked out of the alarm batteries open and filled all of the 6 caps with water.. checked on multimeter.. bam its imidiatly now got 12.7 volt. I put it on a car battery charger.. it charges up and behaves like a new battery. I not currently have a solar system running of 4 car batteries and 10 alarm batteries . every battery on the system bar 1 is over 2 years old and were chucked out batterys due to failure. usually tho if they have began to bulge at all particularly the alarm style or ups style (same batteries) then they usually are not recoverable. 🙂 this seems like something no one believes or is willing to try but it works 🙂 just gotta keep a real close eye on those recovered battery’s to check there not about to fail again because if ones lost a cell then it drains from the whole bank of batteries leaving you with masses of totally dead batteries. 🙂

    for those that didnt know yes you can force a flathead screw driver in the edges of the top of the ups style batterys to reveal the caps .

    all the best
    Jesse L

  • Gary A

    I have replaced batteries in various APC units without problem until now. I have a Back UPS XS 1500 and things seem strange. The dead batteries were replaced with a new pair and re-installed just like the old ones. Initially the front panel showed that they were charging and the estimated run time kept increasing as one would expect. The next day the panel showed no charge and no run time available. Removing the batteries and checking them with a volt meter showed that they indeed, both individually and in series, did show the proper voltage. Any thoughts on what might be going on?

    • Hi, Gary. My first instinct is that something might be wrong with the UPS unit. I’ve kept many of them alive for long periods of time, but sometimes they just go on the fritz and refuse to manage the batteries properly. If it’s an old unit that’s seen lots of action, it’s possible.

  • Steven Offord

    Don’t use a car battery charger for sealed gell electrolite batteries unless it has a switch to select for them, they need a voltage and current limited charge and if given the higher volts and amps that a car battery charger designed for open vented liquid acid batteries they will swell up and split at best or explode at worst & sticky acid gell is not something you want flying around. Otherwise very usefull info.
    I was searching for info. on how much bigger batteries I could connect to one without over loading its charging circuit.

  • Scott Recker

    Hey, great info, and probably what I’ll do with my units. BUT. Since I’m a cheapskate, I wondered about taking it to the next level. Each of the RBC2’s is made up of smaller cells (as evidenced by the little circles on top) hooked together internally. Chances are, only one or a few of these have gone bad. I have replaced individual cells successfully on my smaller battery packs (for radio control airplanes) and wondered if there is a safe way to open up an RBC2 to check and replace the individual cells. Have you seen any instructions on how to do this without splashing myself with battery guts? These cases are pretty well sealed, unlike the shrink-wrap on my little guys, and are kind of intimidating.

  • Mark S

    For the RBC5 I’ve found that 2 of the 12072 battery replaces the original, and according to the information available the 12090 or 1290 will fit the unit and give 9Ah rather than 7.2Ah of run time. I’ve ordered the 9Ah batteries and will be installing them on arrival.

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  • Daniel

    This is a great article!

    I have an APC 1500 that went dead about 3 years ago. I mistakenly attached a laser printer to it. Laser printers have a very high initial load that sometimes make the house’s lights blink whenever it’s switched on. It killed my APC 1500 🙁

    After upgrading to two Back UPS Pro’s, I kept the dead APC 1500 around the house because I know someday it would come in handy if I can just figure out what went wrong with it.

    If I can get it going again as your article explains, can I instead hook up a car’s 12V battery into it?

    I was thinking this unit can be my short-term emergency power. I figured these units are glorified, good quality charger/inverter machines in itself and they can power a cable/modem, cable box, Wi-Fi box, small LCD TV during a power outage. Possibly even have a working telephone (powered or analog).

    You see, a power failure hit Southern California and Arizona not too long ago. It lasted about 6 hours. Fortunately, I found out that the TV cable line was still functioning (strangely enough) and my UPS powered all the cable-related gadgets mentioned above for about 30 minutes. So, I still had cable TV and Wi-Fi during the blackout – watching the news, and using my cellphone’s internet.

    So, do you think it’s feasible to connect a car’s 12V battery into the leads of this APC 1500 instead of its small batteries?


    • I have no idea… but it sounds crazy, and awesome, and now I want to try it! LOL. If you try it first, come back and let me know how it goes!

      • Tom

        I have APC BACK-UPS XS 1300 which died a few months ago. I recently order two 12V 9A replacement batteries to replace it without opening the UPS. Once I received the replacement battery, I opened up the UPS and found there is a single battery inside. It looks like I need a short cable to connect both replacement batteries together. I have contacted the seller from Amazon, but was told that there is no cable available. Do you know where I can get the short cable? Thanks in advance,


        • Man, that sucks. They SHOULD have given you the connector! The XS 1300 is designed to take APC part number RCB 109… which is indeed TWO batteries:


          Normally, you could just re-use the connector from the batteries that were in your UPS, but if there was a single battery in there, then that wasn’t the original.

          You might try contacting APC and see if they can give you one. But you can also build one easily. Just crimp two female spade connectors onto a thick insulated electrical wire (make sure the wire is at least as thick as the original connectors inside your UPS). Then with the two batteries next to each other, connect the “inside” negative terminal to the positive terminal on the other battery right next to it. Then your UPS connects to the “outside” terminals. Lemme know how it goes!

  • Tom

    Thanks for the reply. I asked APC today and no connector is available since I didn’t get the battery from them. I will check Home Depot for the wire and spade connectors.

  • Rao

    Super Article……. helped me a lot Thank you…….Steve

  • Tom

    I couldn’t find the right spade connector from Home Depot and finally found the right connection from Lowes. It is called “disconnect wire connector” and here is the link: http://www.lowes.com/pd_136071-12704-770302_0__?productId=3130409&Ntt=disconnects&pl=1&currentURL=%3FNtt%3Ddisconnects&facetInfo=

    Since the wire inside the UPS is 10 Gauge, I also bought a foot of electrical wire. Here is the steps to make the cable:

    1. Cut a 6″ long eletrical wire and bend it to be U shape.
    2. Put a “disconnects” connector on each end and crimp it tight.
    3. Put a piece of heat shrink tape on each end to isolate the bare metal surface of the “disconnect”.

    I measured the battery with a multimeter to verify it is 12V. Once I use the cable I just made to make a series connection between two batteries and meaure the voltage again to make sure it is 24V now. The final step is to install the battry inside the UPS, which is just to connects the red and black cables to the batteries.

    Thank Steve for this great information and lead me to DIY cable to solve my problem.

  • Mark

    Hi Steve, great info, I have several Tripp-lite Smart700 UPS at work that are slated for the garbage pile, when I plug them in the UPS lights don’t even come on. I removed the access panel and the batteries are swollen. Is it worth buying batteries at this point to troubleshoot or does no lights mean the electronics are fried.

    • Hi, Mark. I’d give the batteries a shot. I haven’t had a situation with my APCs yet (even the really old ones) that a new battery didn’t fix!

  • Mark

    Thanks Steve, I was able to located some batteries, after installing them the Tripplite Smart700 started up no problem, the new batteries did the trick. The UPS must have a cut off of some kind that acts like a relay, when there in sufficient juice in the battery no lights, put good batteries and it lights up like nothing ever happened. I’m going to use the same batteries to retrieve and test the other 4 UPS that are still in the dumpster.

    Thanks again! 🙂

  • joe

    Hi Steve, i’ve been looking at my dead APC UPS for awhile and something in the back of my told me not to order the replacement batteries. Perhaps it was there software that seems to say that there is no choice but to order new ones from APC. Anyway, having read this blog i got curious, looked at a youtube video for how to remove the batteries (i’m all thumbs”) and then search on ebay for whatever looked like a make and model number on the side of the battery. (GP 1272 F2) and I got a link to a place called “Battery Shark” with what appears to be the exact same battery for 12 bucks. But some of the electircal numbers look different in the photo, so I thought I’d double check with you if this is really the same battery. regards, Joe

    • Hi, Joe. It’s probably not the exact same battery you’d get from APC, but if it’s the right size, output rating, and connectors — and the seller has good feedback on eBay, you’re probably fine. I often use eBay seller ecomelectronics. If your UPS is out of warranty, you do NOT need to purchase batteries direct from APC.

  • Jerry

    Hey Steve, great article. I have an old beige APC Back-Ups XS 1500. Never had any problems, never had to replace the batteries. Recently the replace battery flashes red. I got two new batteries, and the same problem, replace battery flashes red. Any recommendations?

    • Hi, Jerry. I actually have a few of those beige units lying around, too! My experience has been, however, that they do eventually croak… and even with fresh batteries, they won’t charge them. I’d try charging the batteries externally if you can (I use a 12V 2A car charger) and see if it still flashes. If it does, it’s probably time to recycle that workhorse. I’ve got an old dead one that I literally use as a door-stop. 🙂

  • Jon

    Does anyone make a UPS device (without a battery) that is designed to be used with a standard lead-acid deep cycle battery (aka golf cart battery)? This would essentially be the electronics of a battery charger and a 120v AC inverter. I wouldn’t mind having a golf cart battery sitting under my desk. Thanks.

    • Not that I know of, Jon. But I’ve always wondered whether small AGM batteries might work (and last longer than SLA) in UPS applications.

  • Thanks Steve! You just saved me $80 between the cost of batteries and shipping. I paid your good deed forward by donating $25 of those saving to charity when I checked out on eBay.

  • Tom

    Hi, Steve. Found your blog while searching for a solution to my UPS acting up.
    I have a CyberPower CP1000AVR. I’ve had it for 6 years.

    -Currently plugged into the UPS: PC with 750 watt Seasonic PSU, cable modem and 27 inch screen.

    -At first, the battery capacity shows 100%.

    -When I unplug it from the wall (or if theres an outage), everything shuts off. The battery capacity drops right down to 40% (shown on the LCD screen and in the software as well).

    -The UPS battery can support the cable modem and an alarm clock for several
    minutes without problems. The UPS came installed with a BB HR9-12 battery which is showing 13 volts measured with a multimeter.

    So, is the UPS or battery at fault? Thanks for any help.

    • Hey, Tom. Hmm… hard to tell, but 9 times out of 10, it’s a battery issue (they are the weak point). I’d go ahead and swap it out to see if it fixed the problem. At 6 years old, it’s very likely.

  • David Calder

    Great Article! I have a question though. Do you know of a UPS that fails safe? By that I mean that when it (or the batteries) croak, it switches to line power. I’ve had two units fail, mid-day, without warning where they shut off power completely (line power is available). One was Trip-lite, the other APC. Ran a power strip to get the units back up, but it seems there ought to be a unit that just cuts over to line power when it fails. Thanks.

    • Hi, David. None that I know of on the consumer side. From that I understand, this happens because the unit is basically “on battery” all the time, so that if it loses power, there’s no interruption. The power from the wall outlet is merely re-charging the battery. That’s why a charged (or at least chargeable) battery is required for it to operate.

      • David Calder

        That confirms what I have found. Seems simple enough to put a relay in that closes when battery power fails to switch to line power, but no one seems to do that. I suppose there is safety or some other complicating factor.

        Thanks for the quick reply

        • The complicating factor is probably the cost of a relay that switches fast enough. 🙂

          • David Calder

            Successfully replaced the batteries in both an old triplite Omni1000LCD and APC Back-UPS XS1000. I thought they were dead since the displays went dark when they failed. As you mentioned above, a battery failure will prevent the info screen and USB communications from working.

            I still think they could set that up so line current relay that would at least show the unit is functioning but the battery dead…very misleading to have it look completely dead and even a slow relay to work off line power would prevent the individual from having to unplug everything and put in a power strip while the batteries are on order.

            Both took the same battery, Vision CP1290A – 12.00 Volt 9.00 AmpH SLA, even though the AmpH on the APC was rated a bit less (8 AmPH) on the APC. The size and terminals were identical. I suppose I’ll get a little more run-time with the APC now.

            Net, I saved nearly a coupl hundreds dollars in purchasing new UPS systems.

            Thank you, Thank you, Thank you.


          • Awesome, Dave. Glad it worked for you!

  • Eric Hudson

    You have indeed an interesting web page Steve – as for APC UPS’s, you are right on the money with the peel their label or clean it off to find out what the battery really is.
    However you may run into the odd one, like I did today.
    Just so you have an idea of me here – Every two years I order in about $7K worth of batteries to rebuild about 60+ UPS’s around my facility here at work. \
    APC really has lost me as a buyer of their UPS’s here in Western Canada – I have a company that makes a great product in Kelona B.C. – Always On UPS and they DO NOT
    play the game – they will tell you outright what battery you need + the comment way back up on your page – I use 12VDC 7.5Ah batteries instead of the 12VDC9Ah becasue they are that much cheaper from Chrismar Battery, my local battery supplier here in Edmonton, Alberta.
    APC has steadfastly refused to tell me the battery type I need, right up until I swore 5 Years ago never to buy another of their units – I can the exact same from Always ON and get the help that I need as well.

  • Robert Rand

    A few cautions about the choice of batteries, plus, I would like to address and set right some of the advise given below.. Caution #1: When using batteries in series, i.e. two 12v (7ah) is the eqivalent of a single 24v (14ah) battery, never use two different batteries by two different manufacturers, always use two batteries from the same manufacturer and make sure the ampere/hour rating is the same for both batteries. For example, a UB1270 has a 7ah rating, and a UB1280 has an 8ah rating. Why? every battery has an internal resistance or R Ohms law says that for resistances in series, the same current will flow through each resistor, and that the voltage drop across each resister (each battery) will be equal or in proportion to the resistance…i.e. E=IR. If the internal resistances are not exactly equal, then the voltage drop (charging voltage) will not distribute (or voltage divide) equally across each of the batteries. One battery will receive a higher charging voltage than the other, and the one with less voltage will probably not fully charge. One battery may be overcharge while the other is undercharging. On most automotive car chargers and on the built in charger within the APC unit, the charging circuit is usually designed to provide a three phase charging cycle/curve. When the battery is fully discharged, the charger will deliver a 7-10 amp charging current for about 2-3 hours or until the battery reaches a certain voltage sensed by the charging circuit. Then the current will be reduced/limited to about 5 amps for about 24 hours or until the battery comes up to about 12v and thereafter the charging current will reduce to about 1-2 amps until the voltage comes up to about 13.5 volts. This last phase is called a float, or float charge. Now understand that the charging voltage for most charger circuits is a bit higher than the battery it is designed to charge. Most car chargers will charge a 12v battery at about 16-18v. After the charge is complete, the battery “rests” and comes down to its holding voltage which is about 13.5v. The float cycle is designed to work with the battery to bring the battery to this final charge state. So why am I explaining all this.Well if you have one battery mismatched that is not getting the proper series charging voltage and as a result does not come up to full voltage/charge, the charging current will be there continuously , one battery undercharged while the other battery may be getting an overcharge. Caution #2:Do not operate an APC UPS on its side. When the battery is installed correctly, the battery should be standing with its terminals at the top during power on of the UPS. In normal operation, during the discharge cycle, salts of the electrolyte will precipitate out of solution and deposit on the lead plates of the battery. During the charge cycle, this spongy crystalline salt material can shock/fracture and fall off to the bottom of the cell. When enough of it collects at the bottom of the cell or builds up to the bottom of the plates, the cell shorts out and current no longer flows through the electrolyte in the cell, but from plate to plate through this “salt resistor” which heats up and runs the cell hot. This heat then in turn will quicly evaporate the fluid from the other cells, and you have a dead battery. Caution #3: DO NOT SHAKE THE BATTERY to see if any material is at the bottom. This will cause any material to float up and wedge between the plates, shorting the plates, and you will loose any remaining life you would have had from the battery. Do a proper charge test instead. Last: When the battery reaches its end of life, you may notice that the cells are swollen and expanding the plastic casing. The battery may also heating up and will not maintain a resting charge, overnight, of 13.5v for a 12v battery…. but will degrade to say 9-11v overnight. At this point, it should be replaced before it damages the APC UPS unit itself.
    As a rule, when lead acid batteries have been in use for 2-3 years, they are done. Even if one of the pack is not fully done, it is next to being done, and you may get only a few more months out of it. Better to replace them all at the same time and know that you are good for 2-3 more years. You will end up replacing them all anyway and if you replace them piece-meal you may not be able to match the batteries properly. Additionally, a new battery will have a different internal resistance that one that has been in use and so the charge across the series pack will not be even for each battery, mixing old with new. As batteries in a series pack age together, their internal resistances change at about the same rate and so charge is maintained evenly. Another reason to change all the batteries at the same time.

    I hope all this helps. R.S. Rand, electrical engineer.

  • Robert Rand

    To dispel another common belief. Charging a sealed gel type lead acid battery with a car charger will heat up the battery and cause it to explode. This is not correct. If we understand Ohm’s Law, what determines current through a resistance is the electric potential (voltage) applied across it. All chargers for 12v batters charge at a voltage that is higher than the rated battery voltage. For a lead acid cell of 12.v, the resting “no load” voltage of a fully charged battery is 13.5 to 13.8v for most manufactures, regardless of the ampere hour rating of the battery, and the charging voltage, car charger, built in charger of an APC UPS unit, or alternator charging circuit of a car, is approx 16v. 16v is 16v is 16v, regardless of what sources it, so the battery is only going to pull as much current as its own internal resistance will a allow it to. CAR CHARGERS DO NOT FORCE CURRENT INTO A BATTERY!. The charging voltage determines the charging current. Charging circuits are usually designed to recognize voltage plateaus and after so many hours when a plateau is reached, the charging circuit will limit the charging current to the battery until it reaches full charge, which includes a float cycle at the end so that the battery can come up to a resting no load voltage of 13.5v. Some chargers have a float switch so you can select just this part of the cycle to “top off” a battery that just needs a little charge. Float settings usually limit the current to 1-2 amps.

    Regards, Robert Rand, electrical engineer.

  • So true! 🙂


      Having just been through this business I can testify that what you say is true. What I found, though, is that ALL of the small sealed lead acid batteries now come from China. The quality is dubious. I ended up buying batteries from Gruber Power Systems – who do warranty their products for a year, anyway. My efforts were successful – but we’ll see how long the new batteries last (Ferrups 1.8 KVA UPS). Several years ago I tried to buy a set of batteries for an electric scooter. I was disgusted to find that the batteries the seller sent me were lower in capacity than the ones I was replacing (1 of 4 of the originals was no good). I eventually got my money back – but not without difficulty. The scooter project is still stalled for lack of suitable batteries. I have no idea where to find what I need.

  • Thomas Lindell

    Despite one of the two batteries in a pack may continue to test good it is generally not a good idea to mix an old and a new battery. 9 times out of 10 the “Good” battery you recycled will fail in short order and when it does it can lead to a early failure of the new battery you paired it with

  • Hi, Norberto. There two 12V batteries in the RBC109 “kit.”

  • lsatenstein

    Here is my very very cost effective solution. I went to a scrap yard and bought two 12 volt 200ah car batteries with top posts (I got a deal –2 for $15. I also bought a large plastic container into which I put these two monsters.

    I wired them in parallel with 14 gauge wire. Actually, I got four host clamps from your friendly Home Depot hardware, I stripped away enough insulation to make a u-shaped loop in the end of the wire and used the hose clamps to clamp the wires in place. I soldered/crimpled two lugs to two extra 14 gauge wires. These lugs match what you would find on the battery terminals.

    Bottom line, I left the UPS with battery door open, removed that 12AH battery and connected my two batteries via my 14 gauge wire in place of that 12amp hour battery.

    So, I have plenty of backup and can almost go overnight with my small load.

    It took a few days to fully charge the two car batteries. I run my ups with about 200VA load, when there is a power failure.

    • That. Is. Awesome. 🙂 I love a mega-hack like that!

  • lsatenstein

    I would like to post a very cost effective solution.
    First, some very simple maths. Watts =volts * amps. If you are supplying 100 Watts at 120 volts, there is a one ampere of current.

    If you want to do the same with 12 volts, it requires 10 amperes of current. A brand new 8 amp hour battery will not last more than 3/4 hour before being fully discharged. And that internal APC battery has about a 3 year lifespan or 5 years if you are lucky.

    I took a 200 amp hour car battery, connected two 14 gauge solid copper insulated wire to it using hose clamps and terminating with two clips that replace the battery clips.
    The typical car battery should last between 7 to 10 years. I used 14 gauge, as it will support 20 amps of steady current. Its the next thickness of wire that is used in home wiring. I bought a plastic container into which I placed side-by-side, the Battery and the Open UPS.

    I use my UPS to keep the power to
    the wireless modem, 10watts
    the VOIP adapter 10watts
    the cordless phone 5watts
    the computer 60watts (when not doing graphics)

    The printer and monitor are not on the UPS.

    A 200Amp hour battery at 12 volts can deliver 2400 Watt hours. At 60watt hour consumption, I can have about 40 hours of UPS backup. If I doubled the 60Watts to 120Watts, my backup will provide power for 20 hours.

    Some more info.
    APC rates their UPSs by Va’s. For example, 650Va’s is about 400Watts A 350Va UPS will support a 200watt draw for under a half hour. With my battery substitute I have at least 20 hours of backup.