Modding a PC Power Supply into a 12 Volt Supply for your DC charger

[racerfred]

Just the other day I put a load of 8.33 amps or 100 watts @ 12 volts and it dropped .37 of a volt. From 12.15 to 11.78, so it could handle a full load (12amps) and not shut down the charger due to low voltage. So if you could get a voltage out of 12.1-12.5 volts by changing the resistor, you should be good to go. I only charge my nimh batteries at 1/2C any way, lipos aren't needed when you just bash.

 

[sudden_scaler]

i use a 250w supply and 8 cells (4 2 cells) at 7a i got 11.37v in pulling roughly 240w. works great!!

 

[racerfred]

What is your idle voltage when not charging and what is the listed max amperage of the
power supply at 12v?

 

[es79]

i have a triton2. a have a really old ATX power supply but it's only 100w +12v@2A -12v@.3A +3.3v@6A 5v@10A. I am unsure if its gonna be powerful enough? can anyone help?

 

[es79]

i have a triton2. a have a really old ATX power supply but it's only 100w +12v@2A -12v@.3A +3.3v@6A 5v@10A. I am unsure if its gonna be powerful enough? can anyone help?

Anyone have any insight?

 

[T-Dubb]

that is the same power supply i use for a triton jr it works ok but i need to try different risistor to get the voltage up it only has 11.48 volts but it has never shut off due to lack of voltage even when charging 5amps on a 5000mah lipo"thumbsup"

 

[es79]

that is the same power supply i use for a triton jr it works ok but i need to try different risistor to get the voltage up it only has 11.48 volts but it has never shut off due to lack of voltage even when charging 5amps on a 5000mah lipo"thumbsup"

thank you much sir...i bought the 100watt 10ohm resistor, which is what I'm guessing your using? its the same one mentioned on the webpage of the original build.

 

[T-Dubb]

It is 10watt 10ohm in the build so that is what I am using

 

[xxgg]

thank you much sir...i bought the 100watt 10ohm resistor, which is what I'm guessing your using? its the same one mentioned on the webpage of the original build.

That will not work,

You have a really old 100W PSU and yet you are putting 100watts of load on 5v rail. Not a good idea.

Just visit your local computer shop and ask for a cheapest ATX PSU. You can find cheap PSU for like $25~30 and it will like be 350W+. Besides, you want a higher Amps on the 12v rail.

yeah, seriously that PSU you have isn't gonna work out too well.

 

[es79]

That will not work,

You have a really old 100W PSU and yet you are putting 100watts of load on 5v rail. Not a good idea.

Just visit your local computer shop and ask for a cheapest ATX PSU. You can find cheap PSU for like $25~30 and it will like be 350W+. Besides, you want a higher Amps on the 12v rail.

yeah, seriously that PSU you have isn't gonna work out too well.

lol, well i'm sorry i miss typed that... 10-ohm 10-watt its a bar type wirewound... i think i do have the right one...

yes, i know i could buy a better one, but i thought the the main concept was to make something from what you already had, if it don't power it properly then i will more than likely just buy a lab power supply...or maybe see if there is a local computer store that will give me a deal...thanks for the catch, you have me scared cause i have already tested it to see if it would run...

it had 12+v so i think it will be ok as long as that bar resistor holds up?

 

[racerfred]

that is the same power supply i use for a triton jr it works ok but i need to try different risistor to get the voltage up it only has 11.48 volts but it has never shut off due to lack of voltage even when charging 5amps on a 5000mah lipo"thumbsup"

If you are not shutting down the charger you don't really need to get you voltage up. If you just want to, lower the value of the resistor to get a higher voltage. 10 ohms at 10 watts is a starting point, imo. I go by my DVM. I was looking for parts for another project and I went to the computer shop for dead power supplies. I got a few and one still worked though the fan was dead. A $3 fan that all was needed. Would any one like to see a "build" or is the info here enough?

 

[sudden_scaler]

worked fine for me

 

[Sokelobo]

what is the best charger for the dollar - venom ?

 

[T3rry]

with my power supply i didn't wnat to spend money on a resistor and had a bunch of LED's laying around so i just made up a small circuit board with 10 leds on it to simulate a load for the 5v

 

[Alhazred]

I'm trying to build one of these.I couldn't find anywhere locally to buy the 10w 10ohm resistor but,a friend of mine who builds guitar amps gave me 2 5watt 12ohm resistors.Does anyone think these will work alright?

 

[racerfred]

10 ohms at 10 watts is a starting point, imo. I go by my DVM.
The only real way to figure out what resistor to use is to measure the voltage with a meter. If the voltage is too low, lower the value of the resistor. Don't over do it with trying to get a high +12, because it may over work the power supply. Bottom line, there is no telling which resistor to use because of the different manufactures designs. It's trial and error.

You can find these resistors at Mouser.com http://www.mouser.com/ProductDetail/...QSGuZcvbhfM%3d

 

[racerfred]

with my power supply i didn't wnat to spend money on a resistor and had a bunch of LED's laying around so i just made up a small circuit board with 10 leds on it to simulate a load for the 5v

I bet it looks cool!

 

[nick344]

nice write up! I know have to find a power supply to mod.

 

[Ax10xman]

Have fun converting a PC p/s. I have.

 

[rollie]

You guys got me on the hunt for a PC p/s !!! damn wish i hadnt trashed the old comps i had laying around...