PC PS as Charger Power Pack?

[orenda635]

I'm going through one of my crazy R/C idea phases. Stuff that seems like a good idea but turns out to be impractical.

Here's my latest. I have an old 250W ATX power supply off my old PC case. I also have a Hobbico Field Charger MKII for my new Slow Stick. Here's what I was thinking of doing.
It's rather simple and doesn't require taking things apart. Take some auto wire. Attach a 12v male molex connector to one end and hook the other end up the appropriate clips that will work with the aligator clips on the charger. Then I could hook the charger up to the 12v rail on the PS. That way I wouldn't need to use my 12v field battery (which I also need for my electric glow starter) when charging at home.

Is this idea do-able or will it fry my charger and battery?

[Chippie]

It is do-able...

If you do a search there are many postings relating to this..

[Norman Adlam]

Hi,

This is one of those questions that regularly comes up! :D (Maybe we should have a sticky answering it?)

Yup - it can be done fine (and is done by many people). The only problems you may have (it depends on the PC power supply) are :-

1) Many PC power supplies require a minimum current that must be drawn, before they will operate. Typically, it's about 500ma - and can be handled by a 10Watt resistor passing the load current across the 12v power line.

2) Most ATX power suplies have external soft-switch lines to switch the supply on, and also have a safety voltage sense line, which if not wired correctly may not allow the supply to run.

(Actually, an old non-ATX supply tends to be better - as it only needs point 1) above addressed)

Cheers,

[orenda635]

As I understand, I'll need to set a 10w resistor between. I won't be messing around inside. I assume I can get the resistor at Radio Shack.

I want to hook it up to the 12v molex line, not the ATX as it sounds like in a lot of articles. The 4-pin molex is what hooks up to you're drives.

[minifly]

yes,
but you need to also short your 'ps on' line (usually green) to a black line (ground, or common) to get the power to your drives to turn on (your cd drives / hdd aren't running when the computer is off, is it? )

the green (or whatever color it is) wire is usually 4th from the left, top row, when the clip is on top and the front of the plug is towards you.

[ebill3]

http://www.rcbatteryclinic.com/
Scroll to the bottom of the left frame.
Be aware that not all Dell PSs followed the ATX color codes or pin assignment.

Bill