turning pc power supply into a rc power supply

andy_666 · 01-14-2006, 03:37 PM

ok since this is a eletric on road im sure some of u have don this so can sombody please tell me how to do this.turning pc power supply into a rc power supply i will be running my charger at 5 amps and a coupple small lights and a cooling fan for my car.help is very apreacated

hurley081182 · 01-14-2006, 03:49 PM

yes i would like to know also

jasong · 01-14-2006, 03:52 PM

here is a link to doing this. It works really good.
how to make a pc power supply into a rc power supply

rockdog200 · 01-15-2006, 07:48 AM

This one works well all so. http://web2.murraystate.edu/andy.bat...owerSupply.htm

ofna · 01-15-2006, 07:55 AM

Just curious.I have two of these.Wonder if they can charge up directly using clips on a 12v Dry cell bike Lead acid batt?

serpentrush · 01-15-2006, 08:43 AM

can these things push out MORE than 5 amps like 10-15 ?

vassago · 01-15-2006, 09:37 AM

LOL, my PSU outputs 26 amps @ 12.01V

Have had 4 chargers @ 6amps (6 cell) running of it, no problems.

Just don't think the cheap ones will, they will deliver maybe 16A or so.

serpentrush · 01-15-2006, 09:50 AM

Quote:

Originally Posted by vassago

LOL, my PSU outputs 26 amps @ 12.01V

Have had 4 chargers @ 6amps (6 cell) running of it, no problems.

Just don't think the cheap ones will, they will deliver maybe 16A or so.

THANKS AND HOW DO YOU WIRE THIS THING UP DO YOU HAVE A LINK

bender · 01-15-2006, 11:52 AM

There is a label on most (if not all) power supplies that tells you the maximum amps for each voltage (3.3, 5.0, 12v).

Most 400-500w PSU usually have a rating of 17 amps or more on the 12v line - which is enough to run 2 chargers without problems.

Just a few notes for those intending to build one:

Firstly, there are several links around to show you how to build one, with the main difference being whether or not to use a load device (resistor or light globe) on the 5v line.

Generally, the 5v line WILL need some load for the PSU to provide enough voltage on the 12v line - how much load really depends upon the quality and wattage of the PSU you have. As an example, I've seen instructions call for the use of a 10ohm resistor, yet my unit runs a 2ohm resistor to provide the necessary load. Some PSU's do not require ANY resistors to work correctly - so there is no real "right way" to do it.

Finally, remember that these PSU's are really not designed for us to open them up and start mucking around inside - so be CAREFUL!

It is possible to make one work properly without opening the case (though it looks untidy) - but if you are going to wire everything up internally then make sure the PSU has been unplugged for a long time - as there as several large capacitors inside that are still capable of giving you a nasty shock.

It's best to completely finish the unit before switching on for the first time.

EDIT:
I have seen a lot of threads on the net turn into nasty arguments over the safety issues with building these PSU's so do not attempt this if you are not 100% sure of what you're doing.

XingXing · 01-15-2006, 03:26 PM

Quote:

Originally Posted by vassago

LOL, my PSU outputs 26 amps @ 12.01V

Have had 4 chargers @ 6amps (6 cell) running of it, no problems.

Just don't think the cheap ones will, they will deliver maybe 16A or so.

hi. just a question? the inside of the PS the wires that come from the PS board to the jacks are only 20Guage wire. I read 20AWG wire should only be rated to around 8amps.

Is that safe to be pulling 20+ amps thru the PS?

bender · 01-15-2006, 03:57 PM

Quote:

Originally Posted by XingXing

hi. just a question? the inside of the PS the wires that come from the PS board to the jacks are only 20Guage wire. I read 20AWG wire should only be rated to around 8amps.

Is that safe to be pulling 20+ amps thru the PS?

Because there are so many of the yellow (+12v), red (+5v), and black (common) wires, you can solder 2 or 3 together to the output jacks and then you'll have no problems

traxxas · 01-15-2006, 07:16 PM

SO to charge the dry cell battery(motorcycle battery),you still need a charger to connect to the PSU?

XingXing · 01-15-2006, 07:40 PM

u cant charge a dry cell with a PS.

u can only charge at a max rate of 30% of the dry cells capacity.

e.g a 7A/hour drycell you can at most put in 2.1amps. it says it on the battery "max initial current 2.1Amp",

then as the gell cell gets charged you have to decrese the amp proportionatly, so when the gell cell is nearly full, its charge rate is prob 0.5A.

Thats how my digital PB charger works.

quantum · 01-15-2006, 07:57 PM

i have done this conversion and it works well, and the 5v tap is nice for powerin lathes etc. BUT what i noticed is that the power supply outputs about 12v max, sometimes it even dips to 11.99v
this can be a problem when charging transmitter packs as those can go up above 12 volts, so what ends up happening is, the charger can not give the pack more voltage than the power supply is giving so it stops the charge (false peaks). most purpose designed power supply's for this application output 13.8v, heck my friend's rivergate outputs 14.1v so i use his when charging my Tx pack.

just my .02

bender · 01-15-2006, 09:13 PM

Quote:

Originally Posted by quantum

i have done this conversion and it works well, and the 5v tap is nice for powerin lathes etc. BUT what i noticed is that the power supply outputs about 12v max, sometimes it even dips to 11.99v

This is where you need to experiment with the load resistor on the 5v line.

Simply put, the lower the ohms of this resistor, the higher the voltage on the 12v line.

As I mentioned, I am using a 2 ohm resistor on my 400w PSU - I get 12.3v under no-load, and 12.1v when using 2 chargers

Of course, you start to generate more heat in the resistor as you boost up the 12v line, so I recommend an additional 80mm computer fan to cool it, plus get the gold-encased heatsink resistor. (see picture)