PSU 12v supply for charger???

[Made2Fade]

Does anyone know a way i can use my spare pc's PSU to power my quick chargers? I dont want to disassemble it and make a standalone supply. Is there a way you can do it while its still running in the pc? Ive heard you have to put a load on them to get them to push the full voltage out. Well if its actually running the pc does this suffice? I know theres a few write ups floating about on the net and i have read them. None of them say that you can or cannot do it while running a pc. Can anyone shed some light here please? Im not planning on using the pc while charging or anything, just basically using it to switch the supply on etc.
Lee

[marktigere1]

Hi Lee

How would you isolate the power running to the PC?

Sounds as though you would have to disconnect all of the power leads just to charge a battery.

If you ran the charger with the PC and charge a high capacity battery, you stand a pretty good chance of overloading the PSU as PC's take a lot of current.

Why not buy a PSU? They only cost around £15 and give out large currents.

I have a 200 watt PSU which charges my FP 1800 mah (LiPO), Twister 800 mah (LiPO) and Futaba kit (2300 mah Nicad) with no problems.

Cheers

Mark

[Made2Fade]

Well in that case ill just take this one im talking about out of the pc. Its a 300 watt PSU. Whats the best way to go on about it then? It has got no switch on it so ill have to short the PS on wire. Is there a way i can convert the molex plugs to use for connecting the quick charger?
Lee

[Made2Fade]

So if i short the ps on wire to a 5+ wire then when i switch the wall socket on will the power supply be on? Also which colour wires are what on the molex plugs? What about putting a load on the supply like what ive read about?
Lee

[robgt]

This might help?
http://www.rcgroups.com/forums/showthread.php?t=368639

I've seen other articles (I used to have a few bookmarked) that walk you through it, however, I thought about it, then just decided to buy this instead

Cheers,
Rob

[jimbob]

The charger would present a load to the power supply Lee....

You need to know which wire are which for a start - be very careful as a mistake will require a new psu.

Look on the motherboard - sometimes theres a silk screen of the voltages.
Normally you will wind 0v, +5v and +12v on the connectors.

If you have a multi meter you could check the voltages on the wires with the PC on.
There's normally a few wires of the same colour, and these would normally be the 0V line. In the olden days when I was a lad they would be black, but now I'm not sure if thats true or not!

I don't think youre safe to do this if you dont have access to a multimeter, and dont know how to use it properly....

No offence intended

[marktigere1]

Hi

Have a look at this link

http://www.rcheliaddict.co.uk/showth...?t=2172&page=2

I think the two wires I shorted together were brown (will check tonight).

Then plug your charger onto the Yellow (+12V) and Black (OV) and then when you connect the PSU to the mains it should start.

Be VERY carefull about not shorting any of the other colour wires or shorting yourself as these PSU's can produce an awful lot of current. Also, never open the PSU case unless you know what your doing as the capacitors inside store massive energy.

Cheers

Mark

[jimbob]

That doesnt sound right to me mark - that would give you an input voltage of 24 volts - is this correct???

Unless by -12v you really mean 0v?

[marktigere1]

Yep sorry.

I've corrected my mistake.

Black wire is 0 Volts or GND.

Cheers

Mark

[Made2Fade]

So mark im taking it that you didnt do anything to add load to the psu? Just simply attach the charger before you turned on the psu?
Lee

[Made2Fade]

If thats correct then all i have to do is short the ps on connect the charger then switch the psu on at the wall??? Or am i just confused here?
Lee

[marktigere1]

Hi Lee

I don't add a load to my PSU (ATX type) just plug in the charger and then plug the PSU into the mains. The charger is a Prodigy II and seems to be enough for the PSU to stay on. Some ATX PSU's do not like a no load situation and will either not switch on or will not stay on when you subsequently plug the charger in (this is what mine does if you switch the PSU on first). You could do what is suggested on some of the links and add a power resistor to act as a load but I didn't see the need.

In order to get the PSU to turn on though you need to short the brown wire to GND. I'm at work at the moment so I cannot check for definate that it is the brown wire. I'll look tonight and post my findings.

I'll also try and take a picture of my setup.

Cheers

Mark

[marktigere1]

Sorry cross post.

Yes Lee

Connect your charger to Yellow and Black
Short the PSU on wire to GND (brown I think)
Plug PSU into mains.
PSU Should start and stay on, then commence charging.

For added safety, I always use an RCD plug to go in the mains just in case. (Belt and braces etc)

Hope this helps.

Cheers

Mark

[Made2Fade]

Kool mark thanks for the info, looking forward to seeing your pics if you can post. Im hoping to get this sorted for tonight. Its gonna save me a right hassle charging my gear.
Lee

[marktigere1]

Hi Lee

I'm home but alas I don't have a digital camera to hand (long story).

However, with my PSU I have soldered together the Green wire to a Black wire and then I connect the positive for the Prodigy onto the Yellow (+12V) and the negative for the Prodigy onto the Black (0V) wire.

Then connect to mains and commence charging.

Hope this helps.

If you still need a picture I'll see what I can do over the weekend.

Cheers

Mark