UPS Restoration and Modification




I recovered a thrown-away UPS with the initial plan of cannibalizing some components, but then I decided to try recover it to working conditions if possible, if impossible go on with the initial plan.

Step 1: Restoration

I recovered a thrown-away UPS with the initial plan of cannibalizing
some components, but then I decided to try recover it to working conditions if possible, if impossible go on with the initial plan.

Usually UPS stop working because of the "dead" battery, because under load its voltage drop too low to power the circuit that converts the 12V-DC back to 220V-AC.
In case the problem were not the battery, the next or maybe the first to thing to check is the fuse. cause is also cheaper to replace than the battery, but is also lesser commonly the guilty component than the battery.

If the fuse is burnt connecting a new battery would make the UPS apparently work but the battery would not be charged (so you can ruin a new battery). So both check that ups runs on battery alone(with AC plug disconnected) and that connecting the AC plug the UPS changes its mode(usually when powered it stops making an annoying sound that reminds you it's running on battery)

Then (of course with AC UNPLUGGED for safety!!) I opened the enclosure unscrewing some screws and extracted the original battery to check it. without load its voltage was correct (a little more than 12V) but once connected back to the UPS and switching-on the UPS the voltage dropped to about 10V. then just to test the circuit I replaced the original battery(the smaller 12V 4.5AH) with a spare one I already had that is bigger (12V 7.2AH) and the UPS worked perfectly. then with the enclosure closed I checked it with AC connected and the

The only concern was the battery much bigger than the original, then I was considering buying a smaller one, put the bigger battery outside the enclosure, and other options but then i realized that with some effort also the bigger battery could fit into the enclosure.

So the UPS was already restored to working conditions, and with longer endurance, but I was not satisfied yet.

Step 2: Modification

I was not satisfied because unlinke other UPS this one had not standard wall sockets, instead had only three IEC C-13 output connectors and the inlet C-14 connector.

So I decided to modify my UPS to have at least one more usual "Schuko" socket.

To do this I removed a C-13 with the help of a little screwdriver

then enlarged the hole, using a manual saw and a file, to accomodate the panel mounted Schuko socket and connected the wires.



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    9 Discussions


    3 years ago

    I would love to do this!

    my APC Back UPS Es 500 has only stupid D-type PC connectors and No standard 3 pin wall sockets!

    1 reply

    4 years ago

    nicely done. that will come in handy


    2 years ago

    I have a UPS that looks just like this. Is this the Centralion Blazer 600? I brought the battery connectors out, so I can use it with an external, bigger battery. At the moment, I'm using a 60Ah battery, and monitoring the voltage with a multimeter.

    It works well, but when I disconnect the mains, the UPS turns off the load after a few minutes, even though the battery is still full (around 12.2V). Any idea why this would happen?
    PS: I also desoldered the buzzer...

    3 replies

    Reply 2 years ago

    does the UPS just suddenly shut-off cutting the power to the loads or somehow make the loads shut down themselves?
    Anyway maybe the working time is preset considereing the capacity of the original built-in battery and it's not based on the actual charge or voltage.
    If it's that the case it's hard to tell if you can do anything about... maybe bypassing the line between the logic and the relay.


    Reply 2 years ago

    It suddenly shuts off power to the loads after *exactly* 5 minutes, regardless of the battery voltage. If I increase the load, it does not happen. I read on some forum (about a different UPS) that some UPSs have a "green" function, which shuts off the loads if the load is below a certain value (some say 10%) for a certain time (5 minutes in my case). Apparently, this is to prevent your PC monitor from draining the battery after the PC has shut down. Clever, but irritating if you want to use it for a long-life, low-load application.


    Reply 2 years ago

    as pure speculation I can say that probably there is some sort of "logic" unit comparing the power load to the threshold and counting the 5 minutes and then turning off the power, and probably the UPS runs until a specific output of that unit is high(for example 5V or 12V) so you can try few alternative strategies:
    1)trick the unit to believe there is a higher load to avoid the shut down
    2)prevent the unit from being able to shut down the ups(for example connecting a 5V or 12V to the unit's output such that is always "high")
    3)another possibility is, in case the timer is represented by a monostable circuit(the same kind used for lights that automatically switch off after few minutes in garages, stairs, toilets), to trick the "timer" to get the shut down time as long as you want. This kind of circuit maybe is implemented with a 555 IC, and in this case the interval is determined by the values of an external resistor and an external capacitor ( T(s)=R(ohm) x C(farad) )....therefore if you understand how it works you can replace the capacitor and/or the resistor to extend the working period