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Disable UPS Charger

Discussion in 'General Electronics Discussion' started by eviveiros, Jun 11, 2011.

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  1. eviveiros

    eviveiros

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    0
    Jun 11, 2011
    I am trying to disable the charger on a Tripp lite internet525u UPS. I have hooked up the UPS to two 35ah 12v SLA batteries in parallel and it works great but I want to hook up an external battery charger and disable the UPS internal charger. Can someone point me in the right direction to accomplishing this. I have good soldiering skills but I'm a beginner at circuitry.

    Here are some images of the PCB.

    [​IMG]

    [​IMG]

    View the photos bigger on my picasa album here
    https://picasaweb.google.com/109006...authkey=Gv1sRgCIm15am-jpml2AE&feat=directlink

    Thanks
     
  2. MagicMatt

    MagicMatt

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    Jun 15, 2011
    You're talking as if you expect the sections of the circuit to be seperate, but in my limited experience of the inside of these things they tend to be merged, and so there wont be a seperate "charger" as such, it's likely to be integrated in with the USB communication etc.

    I'm not sure why you want to use your own charger, but it's not going to be that simple, and as a beginner, you should use extreme caution playing with mains voltages.
     
  3. eviveiros

    eviveiros

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    Jun 11, 2011
    I figured as much looking at the circuit, I'm going to use a 25a diode on the + battery side to keep it from charging it. thanks for the post.
     
  4. fdi

    fdi

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    Jun 24, 2011
    Joining the club

    With power diodes like that the voltage drop is gonna be over a volt, so when the ups is on battery power the diode would be wasting over 25 watts as heat. Also its gonna hugely affect the low battery shutdown feature, so the ups will be thinking the battery is empty too soon.

    I think a better way would be to identify where the chargers output is connected to the battery and then cut that connection and replace it with a little dummy load to keep the charger thinking everythings ok and also hope that doesn't destroy the ups's ability to sense the voltage of the battery.

    I'm currently trying to achieve the same thing with Powerware 5110 which actually comes with a decent smart switching mode charger, however it's not very powerful and it being enabled prevents using the battery pack with multiple ups's.

    [​IMG]
     
  5. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    I guess this is a really good point to ask *why* you want to disable the charger.
     
  6. fdi

    fdi

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    Jun 24, 2011
    That way you can use a more powerful charger that does a better job keeping the batteries healthy. It's also needed when you wanna power multiple ups from the same battery pack.
     
  7. MagicMatt

    MagicMatt

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    Jun 15, 2011
    ??? Why would you ever want to do that? The battery is under strain powering just one UPS, you'll drain it quicker than it's designed to be driving more than one UPS with it, or reduce its life to virtually nothing anyway.

    If you have multiple devices that are low power and need the UPS, just run a multiple outlet extention lead off one of the outputs. It's far safer that way too.
     
  8. fdi

    fdi

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    Jun 24, 2011
    Like OP, I have 2 x 30 Ah batteries in parallel, it takes quite a while to drain them empty and they can certainly power another UPS. Multiple UPS is required when the load cannot be handled by one, or there is need for redundancy.
     
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