RCCrawler Forums

RCCrawler Forums (http://www.rccrawler.com/forum/)
-   Electronics (http://www.rccrawler.com/forum/electronics/)
-   -   Modding a PC Power Supply into a 12 Volt Supply for your DC charger (http://www.rccrawler.com/forum/electronics/163458-modding-pc-power-supply-into-12-volt-supply-your-dc-charger.html)

racerfred 01-26-2010 08:29 PM

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 02-23-2010 10:34 PM

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

racerfred 03-09-2010 03:41 PM

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

es79 03-22-2010 08:19 PM

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 03-23-2010 08:06 AM

Quote:

Originally Posted by es79 (Post 2370942)
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 03-23-2010 08:42 AM

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 03-23-2010 09:50 AM

Quote:

Originally Posted by T-Dubb (Post 2371613)
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 03-23-2010 02:01 PM

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

xxgg 03-23-2010 02:06 PM

Quote:

Originally Posted by es79 (Post 2371696)
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 03-23-2010 10:07 PM

Quote:

Originally Posted by xxgg (Post 2372098)
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 03-26-2010 12:29 PM

Quote:

Originally Posted by T-Dubb (Post 2371613)
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 03-27-2010 12:05 AM

worked fine for me

Sokelobo 04-24-2010 09:53 AM

what is the best charger for the dollar - venom ?

T3rry 05-13-2010 03:59 PM

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 07-04-2010 01:45 PM

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 07-15-2010 03:34 PM

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 08-06-2010 04:42 PM

Quote:

Originally Posted by T3rry (Post 2453102)
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 09-06-2010 06:38 PM

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

Ax10xman 09-23-2010 07:26 AM

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

rollie 10-24-2010 11:38 PM

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


All times are GMT -6. The time now is 09:37 AM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Content Relevant URLs by vBSEO ©2011, Crawlability, Inc.
Copyright 2004-2014 RCCrawler.com