Teardown: Old APC Back-UPS units

[@ghost90able]

One of the best APC ups's to date. I have a back ups 650 from 1993 and it's still working.

[@saba7733]

hey what cords can i use for this? i really want to know my pc has a normal power cord

[@Lion5208]

Hello, there is also an ancient apc 600 ups of 1994 with panel buttons, so the reason right now is that it does not hold a load even a small 60 watts immediately turns off, please tell me where to look, it works from the network as soon as it does not even forcibly hold the load from the battery

[@snrzk427]

@@Lion5208 your battery is dead or the inverter is broken

[@armankordi]

My 650 died valiantly in a surge. RIP 1999-2017 :(

[@DJTheWire]

Yeah but that`s the carrier frequency of the switching supply and even some of the simpler models are quite audible when the inverter kicks on.

[@AintBigAintClever]

The old SmartUPS 600 without user-replaceable batteries was horrible to work on. Big bracket holding the batteries in place and it seemed that you couldn't disconnect the batteries without taking them out, but it wasn't safe to take the batteries out without disconnecting them. I shorted two of the four heatsink plates on one. It sparked, I pulled the screwdriver away but a few seconds later a bunch of transistors on one of the heatsinks decided to catch fire anyway.

[@mrsunelectronics544]

Old APC Back-UPS units with the big switch are cool, unfortunately I didn't find that many ... which are very awesome those from Bestpower! Can be used as an island inverter without mains and they had a great display where you could query all important information ... Voltage batt./outp. performance in% remaining time, etc.

[@jptrainor]

I've got an old BackUPS 500 still powering a small home linux server. I think it's on its third battery. The serial connection works fine with apcupsd. I just tested it after a software upgrade to the server. Still shuts down automatically without a hiccup when the power is cut.

[@drpc98014]

hi, can you tell us how to change the low battery voltage cutoff setting? I have a bk-650 and need to change the shutdown voltage to 11.5 to get better compatibility with lifep04 batteries

[@Yrouel86]

I'm rewatching this video after having pulled out from storage my old BK650MI to attempt to charge an old-ish battery because the newer "smart" APC model (BK350EI) was screaming at me with that battery. Seems to be working, will see if that battery gets a new life. I got both for free (at different times) because they where being thrown away, hauling the 650 home wasn't pleasant but worth it

[@geewizwah2875]

link to the schematic or e-bin, please?

[@Pi-Tutorials]

Hi great video, thank you. I’ve just acquired one of the 300 units, but IC1, the voltage regulator has let out the magic smoke. Could you advise what I should replace it with please.

[@PeterEriksson67]

7815...

[@joelisaiahbobai4331]

must the ups be turned on to charge it?

[@vhm14u2c]

@17:00. You shows schematic for 650 version from web. What google search can I try to find that model or back-ups 250 schematics?

[@FFcossag]

I'm afraid I don't know, I got my schematics from a shady russian FTP site many years ago.

[@joelisaiahbobai4331]

I have the APC Back-UPS 650VA, 230V BK650MI, must a ups be turned on to charge it?

[@hectorluis-ravelosalazar1834]

Hi. I have an old APC Back UPS. The same model that appear on the video BK650MI. I only want to replace the battery, but I don't know what the model of the battery is (the reference). What do you recommend me? Any advice? Sorry for my english. Thanks

[@FFcossag]

+Héctor Luis-Ravelo Salazar 12V 12Ah.

[@wizbang68]

Also note that even APC branded batteries aren't Mfg by APC, if you peal of the silver APC label you will find the original Mfr of the battery stamped into the plastic casing and the details of the battery for replacement. I found this out by mistake when I was trying to find a replacement for an old APC unit I had and the label had been partially scraped off when I was trying to get it out of the case.

[@Kolin4556]

What is the RDS ADJ resistor responsible for, how to set it up correctly?? Without load, for example, the voltage is 230V, under load 200W, the RDS ADJ resistor can set 230V, but there is a large load on the battery, so I set it to 220V, so the UPS works even from a dead battery. But how to really set it up correctly, like from the factory? I understand this is somehow related to the resistance of the RDS MOSFET transistor. Voltage drop regulation under load. I do not understand how to set it up, at what power. The drop also depends on the battery voltage, so it is difficult to adjust it.

[@dhasfhadngsdgsdgrwg]

hello! i know this vid is a bit old but I recently got an old BK300 APC, but one of the white concrete resistors are blown up, i can't find any schematics for that specific model with consistent part numbers! If you still have this one around could you tell me what values those two white concrete resistors are? They are labeled R99 and R100 and are the only two white concrete resistors on the unit

[@FFcossag]

Sorry, I have no idea.

[@SalC1]

The reason I stumbled upon this video is because I have that same Back-UPS 650 you showed that suddenly won't power on anymore. It has a new battery which I tested and is confirmed working. No lights or power to anything. The only thing I can hear is a very faint hum from some component. I may just try replacing some of the few caps on the board and go from there. Edit: I should also note that the battery connection sparks every time I connect/reconnect the battery. I checked the resistance between the battery wires (with the battery disconnected) and it measured at 10ohms regardless of the power switch position. Not sure if this means anything.

[@FFcossag]

Odd! I've never seen one of these fail. Try starting it in inverter mode by holding the alarm or the test button while turning the power on - if it powers on then, it could be a mains sense issue.

[@SalC1]

@@FFcossag Update: I was using a lifepo4 battery in the unit. However, I discovered that whenever I connect the battery, the over-current protection on the lifepo4 battery trips. So I tried a lead-acid battery and it started sparking like crazy. I suspect a dead short whenever a battery is connected to the unit. Now I have to figure out what's causing that short. Possibly bad caps? Only thing is that there's only a few very tiny ones on the board and that's it. Also, starting it in inverter mode didn't work. I tried this without the battery, so that obviously wouldn't work. But I can't try it with the battery because of the short circuit issue. Edit: Ignore the ohm reading I gave earlier. I'm a noob with a crappy multimeter and I probably read that ohm reading incorrectly.

[@FFcossag]

@@SalC1 There isn't much that can be shorted in these except for the switching transistors on the "heat sinks"

[@johnimperial9777]

Does this model got auto shutdown timer?

[@charlesturner897]

iirc you can tweak the resistance between the ground reference pin of the ic and ground to make it output a higher voltage than spec

[@FFcossag]

Yes, you can, by installing a "raising diode" in series with the ground pin. However, these units do the opposite of that, having two dropping diodes in series with the output pin of their 15-volt regulators. Both of these techniques are a bit shoddy in a reasonably high-current (500 mA), high-precision (+/- < 0.2 V) application like this, since the voltage drop across the diodes is going to vary with current, temperature, the weather in Angola, and so forth. Modifying the charging circuit in these units really calls for a new regulator IC to be installed, and the dropping diodes to be removed.

[@MdImran-yp8ik]

Sir my apc UPS AC working okay but I did new battery connection. but not working. only relay working so please sir tlk me my UPS repair tricks

[@kennthbrowne7051]

UPS 350VA 12VOLT BATTERY DEEP CYCLE 75A I GET RUN 9HOURS AND MY BATTERY LEAVE 11.7V FROM 13.7V

[@TheButtercool]

does any one know if theres anyway to mod these (at least the 650) because I got one from a Mac Plus sale and I wanna use it since my power keeps going out because my breaker kinda sucks. The problem is it has outdated stuff (modem,serial, etc) I wanna modernize it with usb and ethernet. Anyone know how?

[@FFcossag]

There's no easy way to add those features, just use it as a dumb battery backup tbh.

[@chriseller1551]

Good day sir. You obviously know alot about these units and i was wondering if you knew how to get a bk300 to turn on by just connecting a battery to it. Like what i need to fuse together on the circuit board or bypass. Thanks

[@johnimperial9777]

Can i put 12 volts 200 ah battery in this model?

[@FFcossag]

No. It overheats fast.

[@johnimperial9777]

@@FFcossag but can i use it as inverter aside from ups?

[@FFcossag]

Not very well. Since it overheats fast.

[@TheJkilla11]

I require replacement lights for the switch or the switch assemble, cant find the switch assemble. any suggestions?

[@QUADBOYification]

Hi, interesting video. Do you know anything about those 4 potentio-meters? Does any of them affect the charging level of the 12v cell. I mean shut-off charge voltage (over-charge protection) etc ?

[@FFcossag]

No, the charger is literally just a 7815 with a diode in series.

[@bowl1820]

Hi I have one of the old APC Back-UPS 600's (BK600C) like those, I hadn't used it in years. I just replaced the battery to use it for my game console and monitor and found the next day the alarm going off (Long steady tone) when turned on even with nothing plugged into it now (also with the battery removed which it did not do before). Was wondering if there was something I could do.

[@FFcossag]

That usually means bad/empty battery. I suggest you verify that your battery still works.

[@bowl1820]

@@FFcossag the battery is brand new and charged.

[@FFcossag]

It's very common for brand new batteries to be dead from the factory, or to fail very quickly. You really need to test it.

[@bowl1820]

@@FFcossag I did test it. The alarm is now stuck on and won't shutoff. Even with old dead battery put back in and it didn't do that before,.

[@paulchristian7513]

Thanks for the video. Not being an electronics tech, are there user-serviceable parts inside ? The reason for asking is that I have two of the UPS Pro 650's ( later model with the soft switches ) both of which failed one month out of warranty. Coincidence ?

[@FFcossag]

There isn't much you can do as a lay person, I'm afraid. It's usually the batteries.

[@SudosFTW]

I use a Back-UPS 300 model BK300C (which was free from work, and $30 for an 8Ah battery from cough-cough-overpriced-cough batteries plus) as my main UPS that keeps my cable modem, gateway router, seperate wireless AP, pogoplug and OptiPlex 760 USFF battery-backed in case of the extremely rare surge, brown-out or black-out. it was an immense lifesaver when Hurricane Sandy hit-- we kept power but it kept the devices safe from all the voltage drops we had during the storm. We had a bit of an issue with a tree on the lines a block over so they had to shut the grid down for a full 8 hours. What ended up happening was, they shut it off at 2PM in the afternoon, and at that time the 760 USFF was still an SX280. so I shut it off ahead of time (to maximize run time) and let the router and cable modem (different setup) stay on with the constant beeping alarm because the thing was running on battery. with my 300 there's no way to turn off the battery, so once every so often you'd get the "hey I'm on battery" beeps. it started getting to low battery about 5 hours in, and then at the 6th hour it finally gave up and shut off, so I flipped the switch off. two hours later, the power came back on and I switched it on. Not only do they sound quiet when they're operating (I can't hear mine at all!) but it's also a quiet charging circuit... or at least quiet enough I can't hear it over the Dell. I'm not necessarily sure how the little thing will take being hooked to so many lower-power devices now, with a blackout. the only time I was privy to that experience I wasn't home. I'm working on moving key services off the Dell now onto the Pogoplug after I upgrade the hard drive in order to bring power consumption off the UPS down to a bare minimum for survival. the time of ARM is upon us for home servers... and for the better, I suppose. Makes me want to do something with this cheapo sylvania ARM netbook I have. I had one running raspbian softfloat back a year ago, but this one's missing the AC jack and I don't even know if it works, let alone having a good battery which I should probably throw away being of cheapo chinese origin. back to UPSes. What would be a safe charging voltage for an 8Ah 12v battery for one of the 300 units? Assuming, of course, the battery is from mid-2012 and has really only been discharged fully about twice in its life inside the UPS.

[@FFcossag]

That was quite a story. As for your charging voltage, 13,6 V +/- 0,1 V is what I usually recommend for SLA bricks in UPS use. It doesn't really change much over the life of the battery, at least not to my knowledge. If your battery is immensely hot or immensely cold, you might need to temperature compensate it a bit, but I doubt that's relevant.

[@SudosFTW]

FFcossag you should do a whole write-up on this all and submit it to hackaday for an article sometime. the way this is all documented in this video is all very easy to understand, especially for someone with not a lot of a foot in the door of electrical engineering such as myself.

[@wizbang68]

FYI you can disable the beep every 5 seconds with DIP switch #1 set to the ON position (disable "Whimper"). The other 3 will be the opposite direction. The UPS will still "Cry" (one long high pitched tone) when it gets below 10% remaining.

[@SudosFTW]

I'll have to try that next time I can be assed to get to it, probably sometime tomorrow after I re-load the little Athlon64 X2 box that sits up there with a fresh copy of Linux. I had to replace the battery a couple of months ago, the old one was run dry and overheating inside. this is the only big issue I see with these units, is they do tend to run the batteries a bit hot on trickle-charge after the battery gets old enough. this last one lasted from October 2012 to April 2016.

[@markmabuhay3271]

I have the same APC Backups 650, may i know if i can replace it with bigger battery- maybe 150-200amps?

[@FFcossag]

No, it'll overheat and break.

[@markmabuhay3271]

@@FFcossag Thank you very much ffcossag for your response!/

[@Drxxx]

how can i connect 2 UPS parallel? it´s possible?

[@FFcossag]

Not easily, it's better to get one big unit.

[@Drxxx]

@@FFcossag but i have only 1000va and 750va, .. how its possible?

[@FFcossag]

You need to hook up the reference clock between them, which can in theory be done, but it's not anything I have experience doing.

[@Muck-qy2oo]

Could you explain what are the exact technical differences are between line interactive and offline ups please ?

[@FFcossag]

Line interactive can buck or boost the voltage without using the battery.

[@Redmi-zs6zn]

please give me the diagram Apc 400

[@eythymiosiosifidis5441]

Absolutely loving your videos! By the way I have the middle 500. However i have used a battery on it and it cannot work off the battery. Any ideas what might be failing? I have checked the 40A fuse it's totally fine, and also measured in the battery terminals 13.5V during operation. Could it be a fault battery? It is a 12V 9AH battery that used to be working fine up until lately acting as a diy ups for a router. Thank you in Advance!

[@FFcossag]

It's hard to say anything without knowing more about the unit. Trying with a known good battery is always a good idea.

[@eythymiosiosifidis5441]

@@FFcossag Yes i will do this. In fact i will try installing a brand new APC RBC2 replacement battery. Unless there is a better choice.

[@FFcossag]

I recommend buying a couple of brand-name batteries and reusing the wiring from your old battery pack. Yuasa/Panasonic last much longer than the low quality batteries that APC use.

[@eythymiosiosifidis5441]

@@FFcossag Good morning. I have just cancelled an order concerning the battery APC RBC2. I would appreciate if you could suggest an alternative model from Yuasa/Panasonic. Thank you!

[@eythymiosiosifidis5441]

@@FFcossag Finally i chose the Hitachi CSB GP1272F2 12 Volt 7.2 Amp. Do you have any opinion about it? Thanks!

[@tourakabed01]

mine still working at the moment

[@kiskiller3]

hey great video but where did you find these schematics ? thanks

[@FFcossag]

kiskiller3 I found them on some strange Russian FTP server, a long time ago. They can probably still be found floating around the net if you dig hard enough.

[@kiskiller3]

FFcossag my 650va had a pot to set the charge voltage and a 317 instead of the 7815 i was pretty surprised. but m8ine is the 120 volt version since im in canada.

[@joseantoniogonzalezmartine1343]

me gustaria consegir el esquema back-ups 650 Mío

[@martinb.770]

I always knew it - the charging logic (it doesn't deserve the expression "algorithm") of these is a farce. 7815 + 2 diodes ... WTF .... who did that? An intern from 1992?

[@FFcossag]

It works beautifully well! The batteries in these last forever since the voltage tends to settle at about 13.6 V.

[@martinb.770]

@@FFcossag Oh c'mon: Compared to the complexity of the inverter part, a linear regulator is an insult! There have been real charge controller out there for

[@FFcossag]

Just being floated at 13.5-13.6 V is just fine in this application. You can't do it in something that sees more than a few cycles a year, sure, but in these small UPSes, it's completely fine. I actually use a bunch of these around the house because the charger is much more efficient than all the more advanced models - the stand-by consumption is only 2-3 W with a full battery. These are some of the best UPSes you can have for battery longevity. I've seen some of these get retired with 15 year old batteries inside that have only barely failed. That is never the case for anything with a "smart" charger since those units universally overcharge the batteries.

[@Kolin4556]

This UPS is not 7815 but LM78M15, it has current protection with a limit of 500mA + 2 diodes, the charger is ready. LM78M15 current protection limits it to 500mA and according to the instructions it is allowed to use it for chargers, it is indicated that it is difficult to damage it. With a load of 1kΩ, it produces 13.6V at a current of ~ 10mA, in this mode the battery will last forever. LM317 + transistor according to the current stabilization circuit = according to the functions of the LM78M15 circuit - but this one is simpler. Both circuits can work for 30 years and nothing will happen to them, just replace the capacitor. As for more complex and efficient chargers, with a controller, a pulse converter. There can be many questions about the charge mode and reliability. Usually, the charge mode does not provide long battery life.

[@hariseka7356]

How to stop with timer in ups apc bp500i sir.

[@Redmi-zs6zn]

Hello! How to disable green mode?

[@matemihalik1260]

Hi there, I see you know these units well. I have a 650VA model (BK650MI, 230VAC). My brother used it for his PC, and once he was playing around with the test button like you did in the video, and something broke inside the unit. The inverter does not turn on when the test button is pressed, or when the mains power goes out. I hear the relay switching but the inverter simply does not turn on and the unit shuts off due to loss of power. Battery charging works. The battery is good, the PCB looks intact, no repairs. I used multimeter to check transistors, mosfets and resistors but they seem to be okay (this is just a semi information though, because I did not solder them out, just checked for shorts and broken/non-conductive components). What could have gone wrong? Some IC got fried? (which I hope not because they are pain to replace) Or bad/aged capacitor? Thanks in advance for any help you could provide.

[@FFcossag]

+Máté Mihalik It's really difficult to say. It could be almost anything from your description. If the entire unit shuts off as if the battery was disconnected, I'd look into the logic power supply stuff, causing the brains of it to fail to run when the charger is not running.

[@oveterinaryTR]

Hi, try to check relays. Sometimes you can hear click sound but relays may not connect. I saw that ;)

[@Kolin4556]

It is necessary to check all transistors and diodes, it is not difficult, mark with a dot with a marker those that have been checked. There are tracks - a fuse, check their integrity. It is necessary to unsolder the output FET transistors and check the generation from the controller with an oscilloscope. Check whether the relay switches, whether the contacts close.

[@Fox15-q5w]

Recharge they salfe?

[@bretislavvaverka2079]

Hi, please is it possible send me scheme of UPS 650?

[@Bobby-lv2kr]

thanks for the video

[@Dark-Wisper]

Hey, I have the 650, a bit different from yours, mine is completely white with black switches on the front, and i guess the battery is dead, because of some strange leak type of mark i saw on the underside of the battery. I haven't opened it to remove the battery, but i ahve a scooter battery, smaller in size, it is a 12V 7Ah battery. On the battery that I have, there is model number: PL7-12. Will it work to be McGuyver style rigged inside just to kinda work in case of a blackout? Like 1-2h on my main computer at home? My computer has a 750W PSU, the total power consumption is unknown, but the idea is to keep it working and avoid any power loss that may damage my computer. Please reply fast, because i have 2 UPS-es, the one you have, the BK650MI and a HP C4777A, both are salvaged from the street, and i want to give them another life. Thank you in advance.

[@FFcossag]

It'll work, but small UPSes like these give you runtimes in minutes, not hours.

[@Dark-Wisper]

Atleast it'll work for a while. Need to understand how to connect that UPS to my PC in order to send a shutdown signal to the PC when the battery is low.

[@Dark-Wisper]

I have tried to connect that battery, it worked for a small amount of time, and whilst it was off, i heard a tick inside, then i disconnected the battery and opened it. I can smell something burnt, like a resistor. What could it burn, and why? Note: The smell comes close to the back, and I can see an array of diodes and resistors there, but no idea if one of them is burnt, also, the UPS when it was functional but not connected to anything, it was making the buzzing sound that is typical to a bobbin working, just so you know, not a hissing sound. No sounds were present during the time the UPS being powered off.

[@FFcossag]

Dark Wisper I really couldn't say, I'm sorry - while I wish it wasn't the case, my telekinetic troubleshooting powers are limited. Some smell could be because of the linear battery charger in these, if your battery is bad and maintains a voltage below 12 V.

[@Alexelectricalengineering]

Thumbs up :)

[@habtamuoluma1140]

I want battery