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Using a Computer Power Supply To Run a Charger

Using a Computer Power Supply To Run a Charger

Old 06-20-2011, 09:34 AM
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Default Using a Computer Power Supply To Run a Charger

I saw in a thread someone say to pull the power supply from a PC and mod it to run a battery charger. I build computers for fun and have several power supplies laying around, is there a write up anywhere on how to do this? I used the search function with a couple different terms but turned up nothing useful.


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Old 06-20-2011, 12:12 PM
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Check this one, he has some for different types also..


Hope this helps
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Old 06-20-2011, 12:38 PM
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Mine works great this is the one used:

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Old 06-20-2011, 01:24 PM
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TV power supplies work too, although I've never seen one handle more than 5A. I'm powering a small charger off of it for my AAA's (1-3A).
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Old 06-20-2011, 01:45 PM
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Used them before. IMHO its doable but too much trouble. Its awesome bang for buck though but some tracks might not allow it... I just ended up with a meanwell from epbuddy.... 20 30 bucks more than the computer supply with similar watts....
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Old 06-20-2011, 02:13 PM
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Something I have found with using computer power supplies is that they do not hold up to their rated amperage...even good ones drop a LOT under load.

I tried 3 different enermax and 2 antec power supplies... all of which report nice stable voltages on the 12V rail, regardless of what I did with the computer....but when I hooked up 2 5A chargers, I could charge at 5A on one of them... but as soon as I add even a 3A charge (giving a total of 8A charge...probably 9-10A draw) the voltage would drop below the threshold of both chargers.

All of these PSUs were rated at 16A or higher on the 12V rail and I couldn't even get half that.

Now, I'm using a proper hobby grade PSU (Protec 20A) and I can get my good LRP charger going at 5.5A, and both of my cheap chargers going at 5A and the input voltage doesn't even waver....
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Old 06-20-2011, 03:21 PM
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My experience is similar to Blue's. Work OK at low loads, but seems many can't realistically handle anywhere near the ratings as we use them. Also many PC supplies don't like the surges associated with charger starts and stops.

There is a possible solution though, server supplies are much more robust, are made to handle surges for hot swapping, and generally focus on just the 12V that we typically need. Widely available used, as servers tend to get updated a lot.
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Old 06-20-2011, 03:26 PM
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Just set one of these up for myself.
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Old 06-20-2011, 05:54 PM
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Here's an excellently done how-to -

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Old 06-20-2011, 10:00 PM
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You just need to add a couple resistors to the 5v rail to boost the voltage on the 12v rail of a regular pc power supply. I use a 450w with a single 12v rail at 24 amps and even with no resistors I've had 2 chargers both pulling 6 amps with no problems.
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Old 06-20-2011, 10:06 PM
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+1 on adding a resistor to the 5v rail...

I've moved on to converting server powersuplies... each one has a different pinout, but when I can get a 53amp powersupply for under $30...

A friend and I had an HP model rated for [email protected], it provided 12.25v from a 1 amp load to when it shut off at 53 amps...
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Old 06-20-2011, 11:52 PM
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Thanks guys, looks a lot more involved than I thought. I am going to have to think this over and do a lot of reading on it...

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