What to do with old PC power supplies

Torqueon - if those variable resistors adjust the voltage, I love you because that's a great idea! What are they rated at? Do they get hot putting all the power through them?

What does the green wire do?

Very cool use of a bus bar!
 
I got two of these proliants pentium 3 power supplies for $30 on craislist. They're 375watts, but I'm sad to say they're not the type all the guides cover and none of the wires match up to traditional ATX power supplies!

Wasps nest!

Those black wires aren't grounds!

I thought it said PS, but it's actually p5, a 3.3v line.

The orange wire reads PG. I grounded it, but it had no effect. The purple one says OFF. The brown and red wires say rs - and rs + respectively.

The thick lead I'm holding goes to the power switch. I was stupid enough not to grab it! It wasn't a normal power switch, and I think it might of been important. I measured some 14v between the red and black wires in it.

Anythoughts?
 
I got the ps running by connecting the red and the black on the power switch line. Luckily it worked with out destroying anything :D

I managed to slightly adjust the voltage from 12.2v to 12.3v by using a 10ohm resistor on the orange PG 5v sense line and connecting it to ground. I'm going to buy a 1k pot from radioshack and see how high up I can take this thing.

Does anyone have any thoughts on adjusting the voltage DOWN wards?

What about using the 5v and 3.3v lines in serial with the 12v line?

Finally, I'm going to float the dc output so I can run the two units in serial without having to float the ac ground.
 
So I've cleaned out the wasps nests and got these dinosaurs running. NOT WORTH THE TIME IMHO. These relics are from a time when 5v was king. They have 9 wires for 5v, but only 3 for 12v. The 12v channel sags VERY badly when any load is applied. Like down to 10v with @ 100 watts!

I'm going to use the two of them as well as the tiny psu I got in series 5v+5v+5v and tune it down to ~14v. These three units will make a really strong 12v, 5v, and 3.3v psu at least!

I contacted a local computer recycler, and they're going to get some newer server power supplies for me next week!
 
yveXH.jpg

Here's my new ghetto charging station. The two 350 watt units are in serial at 5v... they should be good for 72 amps! The small unit is in serial at 5v, but is only rated at 14amps at 5v. It's probably more like 10 amps though. I've tuned the small one down, and the whole system runs at 14.5v.
It sags to 14.25 running the imax at full power. Once I upgrade the small unit to something bigger I should be able to use a serious charger! 14v * 70 amps = 1,000 watts!
I didn't float the dc outputs out of lazyness, but the ac ground floats. It was super simple to float the ac, but the units can't touch or they'll short. I'm going to isolate them better in a box or something because cardboard doesn't seem safe!
 
I was looking for a good power supply and this thread inspired me to try used PC supplies before I put down money on something new. Because I ended up paying for the power supplies I don't think this was the cheapest way to go, there are some inexpensive 24V power supplies on ebay, but it may save me money in the future.

Bought two ATX 300watt supplies from a PC recycler in town ($25 for both) and converted one already. My volt meter shows 12V DC and the line should support up to 13Amps. I had to figure out that the Brown sense line needed to be attached to 3VDC to get the supply to stay on. And I ended up having to use a MAPP gas torch to solder the output wires to the binding posts because my 30W iron couldn't. But hey, now I know how to convert a PC power supply.

One thing I don't like is that the metal housing is also DC ground. I figure I'll just float the AC grounds and put the power supplies separated in a plastic box so I can get 24V DC at <13Amps without worrying about short circuiting something.

Some questions: Is the diode between 12VDC and DC Ground necessary? The power supply seems to work fine without it. I figure I need to get some fuses for the 12V lines just in case I short something. I was thinking 15amp for the fuse size.

Thanks for the idea.
 
One thing I don't like is that the metal housing is also DC ground. I figure I'll just float the AC grounds and put the power supplies separated in a plastic box so I can get 24V DC at <13Amps without worrying about short circuiting something.
Click to expand...

Supposedly it's better to float the dc ground on a unit, but it requires more work. It'd be nice to not have to worry about isolating them though.

Some questions: Is the diode between 12VDC and DC Ground necessary? The power supply seems to work fine without it. I figure I need to get some fuses for the 12V lines just in case I short something. I was thinking 15amp for the fuse size.
Click to expand...

I've used mine for two days without a diode..... but I'm not the person to ask! I'm not really sure....

My volt meter shows 12V DC and the line should support up to 13Amps.
Click to expand...

Very nice. That's a lot of power!
 
Another thing to do with old PC power supplies is to rewind them for single higher output voltages... If you understand SMPS topology, its pretty simple.
 
torqueon said:
Re edited due to info left out and spelling

I have 9 Dell 3r160 power supplies for the old dell optiplex . red and brown are parralell + black and white are parralell - Green yellow parralell, a sense wire. i installed a 10k pot, center to the sense wire, I can vary voltage from 3.7 to 12 volts and the volts hold well while aplying different loads. With a large shunt I charge all 24 headways in paralell for initial balancing, success!!
Wire harness is set up to charge in groups of 12 volts time's 3, so I seriesed 2 dells, set one to 7 volts and varied the other with a 10k pots. This time without shunt, some fiddling it worked out great 1.5 hrs per bank. success!!
Now for bulk charging 36 volts, 4 dellls in series, set 3 at 10.5 volts and vari the 4th one, no shunt Here is when things get weird, as the volts on batts increased i keeped turning up the volt via the 100k pots installed, while watching the volts of each dell after adjustment. increase one and one or the other would drop, all the while total of the 4 units produces the same volts. Much like circus ballon being choke off at varing points and swelling elsewhere.

Notes : Forgot to mention the A C ground must be removed from all.
10k pots used on single PSU and on 2 seriesed PSU
100k pots used on 4 seriesed setup . I bet thats why things got weird, will try again with 10k

Update on 4 series dell optiplex PSU's . I replaced the 100 k pot with 10 k pots, now the voltage and load is stable within the 4 units in series. The batteries are getting a happy meal, I am feeding them 5 amps + or - These PSU units are rate at 12 volt by 12.5 amps, I don't think i can pull that much but 5 amps works for me.

A side note is that i understand there is a bigger similar PSU made by dell rated at 12 volt 18 amps
Click to expand...
 
My 3r160 dell PSU's are working great !! I can bulk charge 36 volts with four in series and can balanace each cell using, one 10 amps no problem. Voltage is adjustable with potentimeter 3.6 to 12 volts
The next step is to make them constant current charge, without having to readjust through the charge. I know tons of write ups on mean wells supplies etc.
Any ideas out there, that do not require E.E. degree would be great !

Thanks to all for including me on the Sphere
 

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Use diodes to limit the volts the battery sees and that will let the ps run at close to full power without going into current protection mode. If you haven't seen this thread yet, It has some info in it.

http://endless-sphere.com/forums/viewtopic.php?f=28&t=12768&p=404521#p404521
 
Is it possible to connect the 12v output in series to charge a 48v pack with just one single ps? this is to be used on the road.
 
adobian said:
Is it possible to connect the 12v output in series to charge a 48v pack with just one single ps? this is to be used on the road.
Click to expand...

I'Ve just realized that it's not possible.The black wire is common ground for all yellow ones.
 
Just one point which is already covered in the thread. PG is power good and requires 3V on that wire to keep the PS on. Sometimes it is purple, or brown or orange and is usually labeled on the PS.
 
Not to rain on the parade here, but just about ever cheap or low end ATX power supply is complete trash. They do NOT put out the rated power, and running them at the limits of what they do run is questionable. You generally need a load on the 5V and 12V rail, they don't have APFC, they don't have much output capacitance, and the voltage tends to sag quite a bit.

400-600W 12V server power supplies can be purchased for $10-20 SHIPPED, and they are designed to run at the rated output power 24/7/365 for years. Most all of them have APFC, tons of capacitance, and the output voltage is really stable without any additional loads or mods. Its not even comparable. I have a few old random computer power supplies, and they all suck at everything. They're just large, cheaply made, garbage.
 
ZOMGVTEK said:
Not to rain on the parade here, but just about ever cheap or low end ATX power supply is complete trash. They do NOT put out the rated power, and running them at the limits of what they do run is questionable. You generally need a load on the 5V and 12V rail, they don't have APFC, they don't have much output capacitance, and the voltage tends to sag quite a bit.

400-600W 12V server power supplies can be purchased for $10-20 SHIPPED, and they are designed to run at the rated output power 24/7/365 for years. Most all of them have APFC, tons of capacitance, and the output voltage is really stable without any additional loads or mods. Its not even comparable. I have a few old random computer power supplies, and they all suck at everything. They're just large, cheaply made, garbage.
Click to expand...
So where do you buy these $10-20 power supplies again????
BUMP
 
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