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Computer charging supply help?

#1
Hey guys I just upgraded to a 200watt 10amp charger from my old hobby king 50watt charger. My power supply keeps cutting out when I try to charge at 10amps. I'm guessing there isn't enough power. My old charger could charge at 4.5amps and that was the max. My new charger it will rise to about 3.5amps and then cut out. The charger is fine because I tested it on a car battery and it will charge at 10amps. The max power of the computer power supply is 330watts but it says 3.3v + 5v + 12v = 330watts. Then it says 3.3v + 5v = 200watts. I soldered all the 12v cables to the banana plug with the same number of ground wires. How can I overcome this or get the most power out of my computer power supply?
 

RoyBro

Senior Member
Mentor
#2
Keep in mind that computers mostly run on 5v. Except for motors of the hard drive, optical drive, etc. So it would make sense that most of the power would be on that rail.
I think you've done what you can to get the most out of the 12v rail(s).
 

xuzme720

Dedicated foam bender
Mentor
#3
So does that read like I think and the 12V looks to have 130W? My supply for my Accucel is 105W and it outputs 7A. Maybe the 12V rating on the comp PS is fudged a bit?

But whatever the cause, it seems you have it wired correctly to maximize the output. Sorry, but I have no suggestions on this one...
 

tramsgar

Senior Member
#4
Modern computer PSUs put most of their power on the 12V line(s), not 5V. The CPU and the GPU are powered by 12V. I'd do some research before shorting the 12V lines together.
 

xuzme720

Dedicated foam bender
Mentor
#5
I know the power rails in the older PS have all been powered from a single buss for each voltage. The reason for splicing them together is to carry the full supply amperage to a single component (charger) where normally, individual components do not pull that kind of current and do not need heavy gauge wire.

Just wondering if the structure has changed on newer PS's?
 

RoyBro

Senior Member
Mentor
#7
Modern computer PSUs put most of their power on the 12V line(s), not 5V. The CPU and the GPU are powered by 12V.
That's very true. With the keyword being modern.

Just wondering if the structure has changed on newer PS's?
I'm sure they have. For one thing they are much more open. I converted an older uATX PSU and later bought a couple of cheap uATX PSUs to convert for a project at work. The newer PSUs were so much easier to work on. I was able to desolder all the wires from the PCB that I wasn't going to use. But that could just be the reduction of the component size.
Also, I'm sure the connections for CPU and PCIe cards are now on separate rails. At least on the better built supplies.
Time marches on. Nothing stays the same. And all that rot.
;-)
 

Tritium

Amateur Extra Class K5TWM
#9
Server supplies are the way to go (under $20 on e-bay for a 62A N750P Dell) BUT make sure it is one with a fan. I use them for Ham Radio Power.

Thurmond
 

xuzme720

Dedicated foam bender
Mentor
#10
Server supplies are the way to go (under $20 on e-bay for a 62A N750P Dell) BUT make sure it is one with a fan. I use them for Ham Radio Power.

Thurmond
That sounds like the way to go. How are you pulling power off of those? Most of the server supplies I've seen are hot swappable and have a slot/plug type interface rather than wires/molex connectors...
 

Tritium

Amateur Extra Class K5TWM
#11
That sounds like the way to go. How are you pulling power off of those? Most of the server supplies I've seen are hot swappable and have a slot/plug type interface rather than wires/molex connectors...
Clips work well, also soldering RC type battery connectors of your preference. You do have to make a jumper to activate power out and slow the fan since it is not cooling a server any more otherwise it sounds like a 60mm ducted jet (it actually is).

Thurmond
 

xuzme720

Dedicated foam bender
Mentor
#12
True, I've installed equipment that the fans go to full speed until the software boots up. Some of it sounds like you're in a wind tunnel!