crazycd1

My Feedback: (2)

I built a 12v power supply from a PC power supply and I have a few questions. Most instructions say to use a light or a 10watt 10ohm load resistor on the 5v line to get the full 12v out of the PS. I ended up using 2 of the load resistors and still only get 11.6v out. Should I pick up more of the load resistors or try something else? Also, it is a 250 watt new style AT PS, so the 12v side puts out 10amps, think that will hold me over? I bought a Duratrax ICE charger and it calls for more, but I am not charging near as fast or as many cells right now as the charger can handle. I did run my Electri-fly 400 charger and it worked great. Well I would appriciate any help guys..

theox

Taken from "The RC Battery Clinic"

The Fix
"By using two easily obtained 1 Ohm 10 Watt resistors (Radio Shack), we can wire them in series across the +5 volt (red/black) output and increase the load on our power supply with an attendant increase in output voltage on the 12 volt line. Both resistors will running at about 65% of their rated wattage and will not be damaged by overload. However, they will get very hot -- the single 10 Ohm resistor was dumping about 2.65 watts while each of the 1 Ohm resistors will generate nearly 2.5 times that. To keep them cooled down, it is strongly suggested that both be attached to the PS case with heatsink compound to help reduce heat buildup.

On the power supplies I have tested, all produced higher voltage levels, with increases of .15 to .2 volts and total output of 11.85 to 12.01 volts.

If you are converting your PC power supply with the intention of driving a field charger, you might consider the substitution indicated above to get a little more voltage. Be mindful that the conversion comes with a tradeoff in the form of more heat. However, a little care in heatsinking your resistors should provide a reliable and long lasting source for regulated DC power."

guver

My Feedback: (325)

Hi, crazy cd,

I see you are in medina welcome.

I haven't had any luck getting over 12 volts either, but the 400 and the ice probly step-up the voltage so it will be fine for you.
It may even power the ice at the maximun rate and voltage too.

I use a 250 watt to power triton to the max. It will deliver about 8 amps at 10.9 volts so it is just barely enough. works good.

crazycd1

My Feedback: (2)

Thanks guys, theox, that is the write up I used and I do have it set up like they say, just still kinda low. Guver, hearing that it powers your triton is good news also, since they are fairly close to being the same. Should be fine for the ICE then...

Edit, I had some LEDs sitting here, I found I can get 12.1v with 6 LEDs and the 2 10watt 10ohm resistors, I will pick up another resistor tomorrow, 3 should put me over and work well! Also, putting the load in parallel gave a high number on the 12v side then series does...

guver

My Feedback: (325)

I tried everything to increase voltage on two of them. Neither one had a pot, but like I said it doesn't matter for the trion cuz it just has to be above 10.5 . The ice is probly the same story. see ya.

Nashcat

My Feedback: (1)

I've found that it's easier to go to Auto Zone and pick up an #1157 brake/tail-light bulb and a pre-wired receptacle to match. Connect the wires, so that both filament are burning. It seems to put enough load on the 5 volt side, plus it makes a nice indicator that the power supply is on. I drilled a large hole and mounted the receptacle in the power supply housing.

Nashcat

crazycd1

My Feedback: (2)

Just an update on my findings, I bought 2 more 10 watt resisters today and with all 4 in parallel, I get 12.12v out!! problem solved! Just wanted to let you guys know incase someone else runs into the same thing..

Andrew

Hi Crazycd1 --

Your equivalent resistance from connecting four 10 ohm resistors in parallel is 2.5 ohms. By connecting two 1 ohm resistors in a series, you will generate a 2 ohm load, which is actually a higher load rating than your present setup. The 1 ohm resistor solution may have given a slightly higher output, but your 12.12v should be sufficient for your needs.

regards,

andrew

Captain351

[link=http://www.mouser.com/index.cfm?handler=displayproduct&lstdispproductid=340282&e_categoryid=354&e_pcodeid=71014]Click Here[/link]

These are what I use. They do the job every time and they have mounting lugs so you can mount them to the case to dissipate heat