How to convert an ATX power supply to rc use
But to answer your question:
A voltmeter is wired in parallel with the 12v output wires. So take the positive lead of the meter and hook it to the +12v output line. Then, take the negative lead of the meter and hook it to the ground output. It looks sort of like this:
POWERSUPPLY(+) ======== OUTPUT_CONNECTOR(+) ===== (+) VOLT_METER POWERSUPPLY(-) ======== OUTPUT_CONNECTOR(-) ===== (-)
POWERSUPPLY(+) ===== (+)AMP_METER(-) ===== OUTPUT_CONNECTOR(+) POWERSUPPLY(-) =========================== OUTPUT_CONNECTOR(-)
POWERSUPPLY(+) ===== (+)AMP_METER(-) ===== OUTPUT_CONNECTOR(+) ===== (+) VOLT_METER POWERSUPPLY(-) =========================== OUTPUT_CONNECTOR(-) ===== (-)
Make sure your voltmeter is classified as DC. Some ampmeters are listed as AC or DC; some as DC only. Also ensure your ampmeter has a capacity greater than the amperage you anticipate drawing while charging. Since your 12v rail is rated at 26A, the minimum size I would suggest would be a 30A meter. If you select one with too high a capacity, the scale will be very broad and you will not be able to get a real accurate reading.
If the amp meter requires a shunt, be sure that it's included with the meter or order one when you get the meter itself. Some may indicate that a shunt is included or built in.
Dennis
This is one heck of a thread!
I got a 375w psu made by dell.
I converted it as per this thread and it worked beautifully
The only issues were finding spots for the 6 banana jacks ( 2 12v and 1 5v)
also it was cramped in there so a little of a challenge!
I am gonna get a hitec x2 ultima. The psu is a bit underpowered and will not provide the full 400w, but I don't think I will be using so much power anytime soon!
Thanks again for the great thread!
Pics attached
(Darn, sorry they are upside down!!)
Hi Folks,
Would this
http://www.ebay.co.uk/itm/NEW-QUIET-...item415e45283e
and or this
http://www.ebay.co.uk/itm/New-850W-A...item4169409931
Be a good purchase? Looks like its plug and play/charge!
Thanks for any input.
Dennis
I'm picking up resistors on the way home to complete my first PSU build.
FWIW, I just de-pinned all the connectors and bundled like colors for the shakedown phase, that way all the sense wires are still attached.
I'm using a 430w PSU that had me all stumped to hell at first. This thing will not consistently turn on with no load anywhere. I hooked a headlight bulb to the 5v and it turns on consistently but dies the second I hook another bulb to the 12v. BUT, if I hook both bulbs in series up on the 5v it turns on fine, I can disconnect them from the 5v and move them to the 12v and it stays on and powers both bulbs...
Bottom line is that this thing def wants more resistance on the 5v than a single headlight bulb to be useful.
As soon as I hooked up a 12v starter or even my charger AFTER the PSU is turned on it did the same to me, it shut down. (similar to VTEC_inside)
If I connect the charger before turning on the PSU, the pSU is fine and the charger can draw current fine.
I did not try high loads yet though, only about 4-5 amp draw on the 12v using a bunch of power resistors in parallel.
Perhaps the PSU is detecting too much of a sudden rise in current and thinks it is a short? That would make sense for the 12v starter as the draw must be initially high as the motor starts to turn and then must stabilize as it turns. The rotor barely moves before the PSU shuts down.
Does that make sense? Did I do something wrong? Do I need to change the load on the 5V?
The PSU is a Dell 375W ATX power supply
Anyway, my token 430w supply is still a bit unpredictable even with the 10/10 resistor on the 5v rail. The other 350w psu isn't particularly happy with it either. Neither will stay on if the headlight bulb it attached AFTER they are on, but the smaller psu wont even turn on in the first place if its there.
Based on my experiments with both bulbs last night, I definitely need more resistance on the 5v to have either one of these working properly.
Now to do the math and see if I can do anything with this 1ohm one.
sigh..
Edit: Found this nifty little program to help me with the math: Electronics Assistant, [link=http://www.electronics2000.co.uk/]http://www.electronics2000.co.uk/[/link]
On my converted ATX powersupply, I have 2 20ohm power resistors in parallel as load on the 5v, it draws about .25 amps each, for a total of .5A total, 2.5 watts or so total.
As soon as I hooked up a 12v starter or even my charger AFTER the PSU is turned on it did the same to me, it shut down. (similar to VTEC_inside)
If I connect the charger before turning on the PSU, the pSU is fine and the charger can draw current fine.
I did not try high loads yet though, only about 4-5 amp draw on the 12v using a bunch of power resistors in parallel.
Perhaps the PSU is detecting too much of a sudden rise in current and thinks it is a short? That would make sense for the 12v starter as the draw must be initially high as the motor starts to turn and then must stabilize as it turns. The rotor barely moves before the PSU shuts down.
Does that make sense? Did I do something wrong? Do I need to change the load on the 5V?
The PSU is a Dell 375W ATX power supply
It works now with the single 10w10ohm resistor on the 5v, but its still VERY sensitive on the 12v. It will turn on with a single bulb on the 12v, but will die if I simply attach my volt meter to it, and IIRC, it wont power up with my multimeter and the bulb on the 12v. I've ordered a bunch of 10w10ohm resistors along with some binding posts now. I think it will be fine with a 2s2p config of the 10w1ohm resistors on the 5v like I originally intended.
For the time being I've trimmed off everything I'm not using, looped and heatshrunk the ends, along with soldering and heatshrinking the power on to ground inside the case. So even though it doesn't work as intended just yet, its starting to look pretty.
NOTE: This 430w supply has a brown wire paired to a ground which I believe may be a ground sense(?). I trimmed and soldered that into the pair of power on and ground I already had.
Usually you cannot safely connect two ATX power supply outputs in series. The problem has to do with the negative leads and grounding................
The 350w is a bit of a strange one. A pair of 10w10ohm resistors in series and it turns on all the time, BUT it will not power on with a single headlight bulb on the 12v rail.
If I put two bulbs in series it powers up fine. Thats a lot of load just to turn on no?
Ideas?
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However, just for the hell of it, I thought that I'd see if the heatsinks were giving off any heat during charging. I touched the left hand sink and it was cold, I touched the right hand sink and it gave the tip of my little finger a jolly good buzz, no doubt the full 240V.
Is this normal? Should any of the heatsinks be live or is something going wrong here?
As far as connections made goes, I simply connected the PS-ON to one of the black ground wires and desoldered all the bunched, smaller gauge wiring and kept the heavy, 12 gauge wires for my outputs.
One other thing, when I switch the PSU on it makes a tick or click sound to the back left of the unit, as you look at the photo. I've eliminated the power switch arcing as the cause as I've plugged the unit in while the switch was on.
Also, it will only make the noise when left unpowered for some time. If I power the PSU up again immediately or within 30secs etc you don't get the noise.
Is this just some characteristic of the large capacitors/toroids on that side/corner? Should I be concerned?
Tom.
Last edited by Tommygunn792; 01-13-2014 at 04:08 AM.