DIY Power supply...UPS Style...

Discussion in 'Anything DIY Related' started by Clownfish9906, 20 Apr 2012.

  1. Clownfish9906

    Clownfish9906

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    hi guys

    I have been donated 2 x UPS - they dead...one does have lights flicker...one doesnt...

    They seem to be damaged. How do I check what works and doesnt...???


    I intend on adding a larger deep cycle battery to the ups instead of the normal one supplied. Have a few concerns, but just need it to start up at the moment.

    Does anyone have an idea of how to test these units??? They are Mercer 1000va/600w units.

    Someone...anyone...please...
     
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  3. Charl_Stanhope

    Charl_Stanhope

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    my one at the office was also dead,I replaced the battery and its working 100% again.it cost me R150. Ive got a spare one that I want to connect to my tank.How do you modify the ups,or the cables so you can use normal plugs instead of the plugs used for a computer.
     
  4. Clownfish9906

    Clownfish9906 Thread Starter

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    i would simply replace the conventional 3pin plug with that of a pc power plug (kettle plug)...should do the trick...
     
  5. mariusmeyer

    mariusmeyer

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    If they are old the batteries will most likely be dead. The batteries they use are not quite designed for a long lifespan. To see if its the batteries you will have to open them up. Not an issues since the warranty will be gone in any case if they are older than a year.

    Test the voltage of the batteries. If they are in the range of 10.5V then they are completely dead. If they are dead you can try and charge them but I doubt they will keep charge.
     
  6. lIghty

    lIghty

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    Yip, probably just a dead battery or blown fuse.

    They normally use a 12V 7Ah or similar battery. not Very expensive to replace, perhaps buy 1 and then test each of the units, BUT please bear in mind, its output is 220V and can KILL!
     
  7. Clownfish9906

    Clownfish9906 Thread Starter

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    hey Marius & lIghty..thx for the comments...

    I've tested the batteries...the one pair seems to get to around 8.5v. They are connected in parallel. The other set dont even get to 0.5v.

    Is there any other way to test them without buying batteries??? i plug in the power and the lights come on...very very dim i might say...

    How can I test the charging capabilities of the unit?

    Could I hook up the multimeter to the +tive and -tive charging cables and measure the dc current it pushes???

    I want to actually get a large deepcycle battery and hook it up to the ups as the battery source...maybe 105ah.

    I am worried that the charging/discharging ability will be bad on the ups. The ups is 1000va/600w...

    Any advice will be highly appreciated?
     
  8. lIghty

    lIghty

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    I can advise you on some things to check, but take no responsibility!

    YOU ARE ALSO WORKING ON A DEVICE CONNECTED TO THE MAINS, SO PLEASE BE CAREFUL AND ONLY PROCEED IF YOU KNOW HOW TO, DO NOT ATTEMPT UNLESS YOU ARE CONFIDENT!

    To check the charging circuit, connect the better of the old battery/s to it, even if it had 2 in PARALLEL, one is OK, but if they were connected in SERIES, then you will need to connect both / ALL batteries as factory fitted. Plug the unit into the main and turn on, Test the voltage across the battery terminals, should be about 13.5V-14v, turn off and unplug once tested.

    Remove one of the battery terminals and place your multimeter between the battery terminals and connection lead, put the meter onto AMP setting. Plug the unit into the main and turn on again, measure the current going into the battery, this could be anywhere from 0.1A to about 0.5A for a flat battery -7Ah. (depending on the size of the battery) Turn off after measurement and disconnect from mains power.

    If you like, you can replace the small battery/s inside the unit for a bigger one (car etc) to test the output stage. connect in the same manner as the smaller battery and then turn on, test the output with a lamp or something. Turn off and disconnect from mains power.

    You simply cant just replace the small battery with a larger one for permanent use, as larger batteries require high charge currents than smaller ones.

    PLEASE, AGAIN I STRESS, DON'T ATTEMPT TO DO THIS IF YOU ARE NOT SURE, AS YOU ARE WORKING WITH 220V AS IT REQUIRES EXTREME CAUTION.
     
  9. chikaboo

    chikaboo

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    As above correct! I wouldn't replace with a deep cycle as the charging circuitry is completely different for the different units .... Neither can you use these batteries designed for a ups on a unit that requires a deep cycle battery ... They will explode! Be very carefull .... You can however get lead sealed batteries with "a little higher" Amp/hour rating ... there are 9A/H available .... All its going to do is give you a longer running time with no electricity but will also take longer to charge as the units charging modules not designed for it ..... Your safest bet would be to replace the batteries in the units and buy 1 or 2 "spare batteries" with an external charging module .... A little bit of extra work but you will be safest this route ..... Every 2/3 months rotate these batteries around with the units ... If you keep this regime up you have 5-7 years lifespan on your batts before replacing them again ... Also buy your batteries from someone that has alot sales with their batteries as you will be sure to get "fresh" batteries .... Ones that are sitting on the shelf too long have dead cells and by the time you realise it the guarantee is over! One last thing ... DONT buy cheap fong kong batteries ......They dont last plus you run the risk of damaging you ups units ......
     
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