Power Supply's atx power supply

murankar

murankar

Staff member
After watching cpo's video on this subject I had to do it. I have a rosewill 500w tax power supply in a tower that needs re-kited. So after watching a few videos on YouTube I was able to make one myself.


I am not sure if this is going to be any better than using 110 vs 12v until I fly tomorrow. I have a battery balancing right now.

ForumRunner_20130120_235130.png

ForumRunner_20130120_235130.png
 
Tony

Tony

Staff member
It will work just fine. All it's doing is taking the 110vAC down to 12vDC. Same thing as the other supplies in your charger. The one that is in your charger is just a laptop power supply. However, you will not be able to charge over 50w even with a larger power supply. the wattage is built into the program. I have already tried this. You will have to reflash your charger with new firmware to raise the charge rate.
 
murankar

murankar

Staff member
Not sure if I want to do that. All though I would love to see faster charge times. My batteries can handle 5c charge rate according to info I found on misc web sites.
 
callsign4223

callsign4223

Staff member
Will flashing the firmware and charging at higher rates damage the charger? Is it only limited by it's power supply, or is it a limitation of the circuitry inside?
 
murankar

murankar

Staff member
I am sure that it can handle more, but the manufacture says this is what we want to say it can handle. Almost everything in electronics is labeled under what it can really do.

I was looking at chargers that are more pricey. What charger would be a decent upgrade.
 
Westy

Westy

LEGEND
hey.... Murankar, what did you use to load up the 5v side to stabilise the 12v side? I used 2 bulbs in series. This was due to apparently the 12v step down will not handle the amperage loading until you place a decent load on the 5v side.

I can actually verify this as I could only get my 500w PSU tht I modded for this same job to hold above 10v upto 4500MAH (11.4Amps). It would trip out the lipo charge on an under 10v alarm and the whole battery charging routine would stop and "INPUT VOLTAGE ERROR" would come on the charger.

After I first added one 12v/ 5w car bulb ... and then another .... I can now run dual 5000MAH charging and consistantly run the charger without a low voltage error since. It is consistantly running at 16.5amps and holding about 10.37V and no lower.

will be interesting to see what yours will handle as far as current draw.

The other option is to get one of these::

20AMP CHARGERl

or

25AMP CHARGER

or

The BEST DEAL I THINK 35AMP = BE VERY CAREFUL THAT YOU SET THE VOLTAGE CORRECTLY.
USA CUSTOMERS, SELECT 110V ON THE BACKSIDE OF THE POWER SUPPLY UNIT!
 
murankar

murankar

Staff member
Not sure about that. I did not see anything on that. I have only balanced my batteries with it so far. My charger tops out at 50w at 5.0amps. So I am not pulling a whole lot as of yet.


I would need to see what it was you did with the 5volt side
 
Westy

Westy

LEGEND
I simply took one of the Red Wires (5v) and a black (Earth) wire and soldered a 12v/ 5w tail bulb between the 2 ... I then retested the set up and found that I had increased the cut off point where the voltage dropped below 10v ..... (this meant I could load it more as the amperage was increased under load.

So I added another bulb and it increased to the rated output of my PSU to 16.5amps .... under load .... but would not hold 12 Volts .... dropped down to 10.37 but it was stable at that and did not trip out my charger any more. Hope that made sense :)
 
murankar

murankar

Staff member
I need to find a cosmetic way of doing this. Maybe I can find some LEDs that I can mount on it.

I also have a 12v case fan that I would like to use as a way to blow air across the charger.
 
Westy

Westy

LEGEND
no can do...... Led's are lucky to draw 20 milliamps ..... only other way is using a shunt and a potentiometer mounted in a seatsink to dissipate the heat load..... that way you can "tune the PSU" to get max output efficiency
 
murankar

murankar

Staff member
Looks like I need to some research. So for now I should be good unless i decide to get a monster charger.
 
RandyDSok

RandyDSok

Well-Known Member
Using the AC6 Charger... a seperate power supply will do little good since it already has a PS that can supply what it needs to charge up to the rated 50w load. People use an ATX ( or other PS ) to provide power to the DC input only chargers... not to ones that already include an AC input.

Rosewill actually sells several different 500w PSU's... not just one. Which model you got will determine the possible output that it can provide. The two lower cost models that my vendors carries, have the same specs. I believe the one in the OP's picture appears to be the RD500-2SB model which actually has two seperate 12v+ rails, one rated to handle 15a and the other 16a... Between those two rails they have about 350w of power split between them... so each rail can handle around 175w more or less ( 180w on the 15a, 172w on the 16a rail). The math for the values they have printed isn't exact but it is pretty close.

So if you do get a charger than can use between 170-180w of power... this PSU should be about to handle it or at least be close to providing the power needed for it. For the AC6 charger you have... it is not needed and gains you nothing really.
 
murankar

murankar

Staff member
Well this was a quick project as a shiza and giggles deal. I now have a backup power source or an upgrade to a better charger.
 
Tony

Tony

Staff member
No need to use a light on the +5v side, you can just use a resistor to do the same thing. I can't remember what resistor I have, but it's a ceramic one that I have glued to the heatsink in my PSU. Worked great until I blew a cap in it.

I will try to do a video on how I did mine and make another one out of another supply that I have laying around. You can ask Matt, I have a few computers laying around lmao.

What Randy said is 100% truth. The AC6 has the "laptop" power supply in it as I listed before. The 50w limit is NOT ONLY from the PSU, but also programmed in the software. It WILL NOT allow the charger to charge over 50w, I have tried and failed. Reflashing it won't work as I have not found a way to do it nor what program to use that will read the program that's in it.

This is a good test for those that purchase a DC only charger as Randy stated. For the dual power chargers (AC/DC, great music!!!), you don't need to do this and will not accomplish anything more by doing so.
 
Tony

Tony

Staff member
FYI, a 10w 10ohm resistor will work. This sounds close to what mine is but I will have to look to be sure. Will be looking into this when I get home. If I don't forget lol.
 
RandyDSok

RandyDSok

Well-Known Member
I'll add one other tidbit of info for those that are thinking of doing something like this...

PSU's can have a single or multiple rails. The PSU used here has 2 +12v rails ( the photo of the specs show a +12v1 and +12v2 )... This is used to help isolate the circuits in the PSU in the event that one rail goes down from an overload on that rail, the other can still work in certain circumstances. While I still prefer a single rail for computers, multiple rails do have advantages still.

For a PSU that you plan to use to supply a single charger... a single rail PSU is the way to go. This way, the amperage isn't split up and all designated to the +12v is available for your charger you plan on attaching. A similar 500w 30a output PSU would be able to provide around 480w ( some of the 500w is being used to feed the +3 & +5 as well as the -"- leads ). This would just get you into a good entry level charger setup ( for higher end chargers ).

A setup that is on the upper high end... needs a completely different class of PSU, one capable of 1500w and 24v.
 
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