Making 12V DC Converter from PC Power Supply

3001 Views 33 Replies 11 Participants Last post by jimross (aka Cool Pig), Dec 3, 2004

3d-aholic

Discussion Starter · Sep 1, 2004

There's an article on BatteryClinic
http://www.marcee.org/Articles/PCPowerSupply.htm that describes converting a PC power supply to use a 110 to 12V output DC Power supply.

Anybody done that?

The problem is this.

I ordered a Great Planes Triton from Tower and it says this in the docs.
COMMENTS: To achieve the Triton's maximum potential, the power supply must be capable of delivering at least 13 amps of current while maintaining 12V DC.

All the computer power supplies I can find don't seem to achieve this level of amps. Is this simply something Great Planes says so you have to buy their DC power supply? For example, I have identified an older power supply I don't need but the output is only 7.3Amps. The biggest computer PWS I can even find are the brand new ones and even those don't go higher than 9ish amps. The article agrees that a 7-8Amp seems to be average. What do you think, will it work in your guesstimate...is this a rouge by Great Planes after the aticle was written? I ask this because even the DC power supply they recommend only puts out according to the description

Handles up to a 11.5 amp load.

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PaulSwany

· #2 · Sep 1, 2004

I converted a few old power supplies using that article.... It's a pretty easy process.....

However....

It's kind of a crap shot as to getting one that works the way you want.... The first one I did will power itself off if I hook up the triton to it after it's turned on... However.. If I turn on the ps with the triton connected, it works fine.... The other one I did for Gator works fine....

btw... I couldn't get the first one to work at all until I added a tail light to the circut to pre load it.

3d-aholic

Discussion Starter · #3 · Sep 1, 2004

PaulSwany said:
btw... I couldn't get the first one to work at all until I added a tail light to the circut to pre load it.

lol...thats got to be funny to see. Hopefully you got the tail light hanging outside. :lol:

This is really old style AT PS so I don't think I will have the power with the tail light requirement you are describing. That sounds like the new ATX PS. I just think that 7.4 amps is way less than what Triton claims is the minimum at 13 amps. The PS they recommend though is 11 amps.

What Amps were your PWS's putting out?

So what your saying is that you try it...the only way to find out.

Gordo

· #4 · Sep 1, 2004

I've been useing mine for months. I can charge at 5 amps into my lead acid, and I believe that is the maximum the Triton can charge. We had 3 hooked to it in Houston with Lipos and planes cahrgeing all day.

I have a sheet that tells you how to do it (I used a very small 12v light also) and tells you what to look for in a Power Supply. If you need it, let me know. I took it into a computer graveyard store, the guy knew just what I was doing and what I wanted!! LOL :lol:

PaulSwany

· #5 · Sep 2, 2004

I think my PS was only rated at 7 or 8 amps...

3d-aholic

Discussion Starter · #6 · Sep 2, 2004

Ok, I can was thinking this. I think I'm set how to do it. I've already found the +12 volts.

Hey, can you hook up several of these 12 volt lines and get more amperage or does that voltage add up instead....? Do you guys know?

Thanks for your help.

Gordo

· #7 · Sep 2, 2004

Hooking them up is parralell would up the current supply, series would up the voltage (or blow them up) just like a battery. But there are other concerns here too..........I wouldn't do it.

PaulSwany

· #8 · Sep 2, 2004

If you look at the circut board... all the yellow 12 volt wires go to the same place.... So you'll just make it a little easier on the wires if you use more than one... You can do the same with the black ground. Won't change the available amp draw however.... That's dictated by the guts of the PS.

3d-aholic

Discussion Starter · #9 · Sep 2, 2004

Ok, but then it would keep those tiny wires from heating up to the point of high resistance and thus make the 7.2Amps more available. Those thiny wires the give you seem a bit small for a constant 7.2 Amp draw.

Thanks for everyones help.

PaulSwany

· #10 · Sep 2, 2004

I agree... Go ahead and use 3 or 4 wires in a bundle to not allow any bottlenecks.

3d-aholic

Discussion Starter · #11 · Sep 2, 2004

Thanks.....Paul

PAR

· #12 · Sep 2, 2004

I've seen many people using computer based power supplies with many different chargers, myself included, without problems. The only time you might need the full 13A input is if your using the charger at the limits of its capacity.

steener

· #13 · Sep 3, 2004

I have an old DTK power supply that the output is rated at 200watts. It works fine but needs to be preloaded or it will shut down. A resistor, light bulb, or any other SMALL 12v load will work. I tied all the 12+ yellow leads together and used the one large black ground. Then I cut a 2x2 piece of plastic from an electrical box and screwed it to the ps. Then i bolted two #8x1" screws to the plastic and crimped eyelets to the leads to go under them. Woolla, 12v power supply that works great. BTW put the load between the two screws to preload the ps.

Spaz

· #14 · Sep 4, 2004

The only time you might need the full 13A input is if your using the charger at the limits of its capacity.

like PAR said, if your just charging some lipos or 8cell packs you wont have any problem, the worst thing that can happen is the PS will thermal overload and shut down or the triton will shut down from low voltage.
goforit

RSands

· #15 · Sep 8, 2004

Check out All Electronics for power supplies. They're prices are great and they buy liquidation stock from all kinds of sources, so some of it is pretty heavy duty. I bought a 500 watt supply from them for ~ $25, and it's built to military specs. The things got dual cooling fans, a solid aluminum rack mount type case, overload protection, etc. Hate to think what the gov. was paying for them. :x Stock changes, so it pays to check them out every once in a while. Here's a link to the power supply page.

http://www.allelectronics.com/cgi-bin/c ... type=store

3d-aholic

Discussion Starter · #16 · Sep 12, 2004

My power supply is NOT working!!

If I put the charger on, and turn on the supply it works until I do the battery check on the Triton. The battery check seems to cause the charger to turn on and off or something and the supply folds on itself and shuts off. If I attach the charger with the supply already on, it shuts off.

I tried using a little 12volt light bulb....but it didn't seem to help.

Gordo

· #17 · Sep 12, 2004

Did you have dirrections? I mean, they give explanation of what isn't a good choice and what is in a power supply, maybe yours isn't a good one to use???

3d-aholic

Discussion Starter · #18 · Sep 13, 2004

Probably...

But, mine seems to have the preloading problem everyone else overcame with a lightbulb. Do you need a sufficient sized load on the PW supply so it doesn't fold-over?

Gordo

· #19 · Sep 13, 2004

I don't remember a specific size load, I have a very small 12v bulb on mine. I'll look and see.

3d-aholic

Discussion Starter · #20 · Sep 13, 2004

I bought 2 red bulbs from radio shack. You can't even see the bulb, but it says 12 volts, 10,000 hours. I wonder if its too small.

1 - 20 of 34 Posts

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