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Scrounging a UPS

TheHaul We have been doing some alternate energy projects here at uCHobby and needed some big batteries to charge with solar panels or wind generators. I looked though my “To-Be-Scrounged” collection and found a large UPS (Uninterruptible Power Supply) This UPS had two large Lead Acid Gel Cell batteries and lots of other useful parts. More after the jump.

To read more about scrounging electronics parts check out my dedicated pages on scrounging here.

UnitHere you see the backside of the UPC ready for scrounging. This unit had been removed from service because it was beeping too much. I just got tired of hearing it so I replaced it and put it in a junk pile to scrounge from later. I knew it would be full of power FETS and some day I would need them.

CoverOffPictured right is the insides of this UPS. The large heat sinks are visible as fins near the center of the picture. Each fin has several power FETs to scrounge.

We only went after the really choice parts initially. The main PCB was saved till we have time to remove all the large power FETs and a couple of current sensing transformers but for now we recovered some interesting items.

The Haul

  • 2 Large batteries
    The capacity was not marked but I would estimate each at about 20Amp-hours. The condition is suspect as the UPS was not in use.
  • 1 Large transformer, used to convert the chopped 12V to 120V AC.
  • Some heavy wires
    • Used to connect to the batteries and other high current points inside the unit
  • Circuit Breaker
    • Panel mount protection, very easy to reuse
  • 2 standard AC outlet jacks
    • Just like you have in your home, in the US anyway.
  • 2 large capacitors
    • Strange in that they have three pins
  • 16 small transistors
    • There were more I just took the ones there were near other parts I was removing
  • 1 beeper
  • 2 PCB mount switches
  • Some LEDS
    • These LEDs were very hard to remove. The heated legs separated from the LED plastic. I tried to salvage several LEDs but almost all were destroyed in the process.
  • Some resistors
    • There were a ton of resistors. I really only pulled a few that happened to be in the way. The leads are short on these resistors and resistors are so cheap that it’s not worth the trouble.
  • 40 Pin IC Socket
  • 2×10 ribbon header and cable
  • 1 Crystal – Don’t know the frequency yet.
  • 1 PCB Mount pot, 50K
  • 27 Caps with leads barely long enough for breadboard work.
    • I could have pulled 50 more but just don’t need this many.
  • 2 three terminal voltage regulators 5V and 12V
  • 1 IRF610 power FET
    • There are dozens of these but they are hard to remove. Each one is riveted to a large heat sink. I have to drill out the rivet to get the FET. I kept the main PCB for scrounging later as these are very nice parts.
  • 10 DIP ICs.
    • 2 UCN2251A transistor driver IC
    • 1 40 Pin chip that I can not yet identify. Phillips 356-0002C or KTL9909. Probably a custom chip.
    • 1 ADC0838CCN A/D converter
    • 2 LM393 Dual Comparators
    • 1 93C46 Serial EEProm
    • 1 74HCT257 Serial to Parallel Register
    • 1 CD40106

There were other parts including a nice DAC chip that I destroyed while trying to remove it. I found that for ICs the best way is to use a small screwdriver to pry under the chip. This board was especially difficult to scrounge partially due to a very dense ground plane and because all the leads were bent over under the parts. It took some force to remove parts like ICs and several were broken in the process.

Posted in Discovering, Parts, Projects, Scrounging, Scrounging Parts.

10 Responses

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  1. Cam says

    I took apart a similar UPS the other day… Looked almost the exact same. Same philips chip, fets with “heatsink” plates, ceramic cap, looks to be the same transformer… except it was a different UPS. Like, smaller / smaller batteries / few different circuit components. Eerily similar, though. I only kept the transformer, circuit breaker, a big ceramic cap, and the steel housing for very unrelated reasons.

  2. Mike says

    I’m pretty sure the transformers in UPSs are used both ways — 120V -> 12V && 12V -> 120V… Would need the 12V to charge the battery from mains..

  3. Norman says

    I believe the 14v -> 120v transformer that I salvaged was on the order of 500-1000VA, meaning that the output current (if used as 120v -> 12v) could be up to 100A (input to the UPS is on a 10A breaker at 120VAC).

    Also, did you ever figure out what the 3 pin power caps are for?

  4. dfowler says


    The transformers should work in either direction. The only concerns would be the intended current in each of the windings. Be very careful while playing with 110VAC.

  5. Mike Yancey says

    I just received a couple of rack-mount UPSs like this, with similar HUGE transformers. I wonder: a) can the transformer (reliably) be used in reverse? (120V down to 12V) and b) what would be the approximate current rating.

    Mine were discarded by the company I work for (a large corp), probably due to end-of-life of the batteries and the fact that the computer interface is serial, not USB or Ethernet.

  6. Norman says

    I just recently salvaged a APC Back UPS 500, took one battery out of it, a similar 14-16v -> 120VAC transformer, 4several NDP6051 (50V 48A) N-MOSFETs, 1 or 2 7400 IC’s, some various other resistor/capacitor type parts almost not worth saving, switches, and the case itself which with the transformer makes the perfect case for a homemade benchtop power supply.

    In terms of UPS’s, the newer plastic cased UPS’s won’t always have beefy transformers, and also they won’t make the most useful cases.

  7. dfowler says


    Wow… Guess what, we are planning something like that. This UPS was not selected for that potential use but I have anohter, even bigger one that we plan to do somethink like that with.

  8. Berni says

    Why not use it as a inverter to get mains from your baterys and wind gerenator.

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