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I have new 600W ATX computer power supply unit. I have wired green and black together to make power supply turn on when plugged in. I wanted to charge my 12VDC empty battery, without dealing damage to it "or overheating it using a PSU". I do know ATX PSU color codes (black = ground/0V, orange = 3.3V, red = 5V, yellow = 12V). I saw some people used controller to "limit the transmission." I don't want to damage my battery or either PSU for future use. Since I don't have multimeter... EDIT: I forgot to mention that I wired yellow (12V) from PSU to "+" on the battery, and black (ground/0V) from PSU to "-" on the battery. Question: Have I done it right?

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    \$\begingroup\$ No, you have not. You are likely to lose the battery this way, and possibly the PSU, and maybe some of your property and/or your life. \$\endgroup\$
    – Ignacio Vazquez-Abrams
    Commented Jul 1, 2014 at 15:54
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    \$\begingroup\$ 12V isn't suitable for 12V battery charging. You need a higher voltage (it depends on the battery type). \$\endgroup\$
    – Leon Heller
    Commented Jul 1, 2014 at 15:55

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  1. Battery with nominal voltage 12V usually is charged with a little higher voltage. If this is lead-acid battery - that voltage should be 13.8 - 14.4V.

  2. Computer power supply is definetly not designed to be connected to battery. Partially discharged 12V battery can have voltage higher than 12V. If you connect it to computer power supply - you may feed power supply with energy. Power supply will "see" too high voltage on its output and will try to lower it to 12V. Depending on design of that power supply - bad things can happen.

  3. You would need some circuit to limit current or some battery charging circuit anyway. Depending on battery type and size - you will probably damage battery or power supply. Battery can even explode, so never try charging when you can't measure current.

  4. Many (if not all) computer power supply units can't work without some minimum load. You shall not power on computer power supply without load.

If you have no multimeter and no experience with electronics at all - I would recommend you to buy battery charger for that specyfic battery type (chemistry) and size.

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    \$\begingroup\$ I do have little experience. But, thanks for warning. I'll rather order a battery charger :) \$\endgroup\$
    – OmegaExtern
    Commented Jul 1, 2014 at 15:58
  • \$\begingroup\$ @OmegaExtern I added one more warning, see my answer after edit. \$\endgroup\$
    – Kamil
    Commented Jul 1, 2014 at 16:03
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    \$\begingroup\$ Yeah, I am watching it all time. And I forgot to mention I have actually connected car stereo to the battery now, and it plays, looks like battery got charged... \$\endgroup\$
    – OmegaExtern
    Commented Jul 1, 2014 at 16:05

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