Seems like a lot of work and hassle when you can buy a battery charger for
$20 to $50.

> I've been talking with another listmemember about making a 12v batter
> charger from a pc supply according to some directions my dad found.
> Thought I'd go ahead and distribute to the group. The idea is to
> install this in my camper so when I'm plugged into 120v at a campsite,
> I'm charging my batteries automatically. My dad pointed me to a
> magazine article that detailed the process. Look for a 10 or 15 amp
> power supply to begin with. I know virtually nothing about electricity,
> but it worked till I fried the board with a microtorch. Will be more
> patient next time.
>
> Here's how they did it. It's in September 2003 Model Aviation, and if
> my description doesn't work, email me and I'll send you a copy of the
> article.
>
> 1. Make sure it works, if you can. My first one did not and I didn't
> know it until I had done all this (only takes 15 minutes or so, not
> counting the trip to radio shack if necessary).
>
> 2. Cut ALL the wire off at 6 inches.
>
> 3. Remove the "motherboard"
>
> 4. Locate the black ground wires and clip all but two close to the
> board.
>
> 5. Locate the +12 wires, and clip all but two close to the board.
>
> 6. Locate the -5 stuff, +5 stuff, -12 stuff and anything else and cut
> it off as close to the board as you can.
>
> 7. Take a soldering iron and open a hole in one of the cropped +5 wires
> and another at a ground hole.
>
> 8. Now, you should be ready with two black grounds, two reds (or
> orange) +12v, a hole at one ground and a hole at one +5v.
>
> Everything else should be gone.
>
> 9. Now you are going to run a load between +5v and ground using the two
> open holes. The load is what the PS expects to see in a device such as
> a hard drive.
>
> 10. The article suggests that you use either a 1 ohm, 25w resistor or
> an automotive light bulb type 1156 or similar to provide this load. It
> says that the light bulb is nice because you can read by it and it
> serves as a pilot light, but he actually ended up using a Radio shack
> 50-ohm, 10W resistor (RS item # 271-133). That didn' t work for me, I
> went with a resistor somewhere close to the 1 ohm 25w which worked
> fine. He was worried about the inefficiency of the latter, I was not.
> The author warns that you may need to experiement as all the PSs are
> identical in many ways but subtly different in others.
>
> 11. Take the two reds and the two blacks and double them for the
> increased current to the battery.
>
> 12. Cut a strip of plastic that will span the two holes in the metal
> case of the PS (assuming you removed the plastic grommets that secure
> all the wires through these holes, and you bridged the wires properly
> to obviate the switch). Drill the  plastic in the two holes for Radio
> Shack Multipurpose posts 274-661. Mount the posts in the hole in the
> plastic you mounted behind the metal holes in the case, and run the
> respective wires to each. Now you can have screw on and banana-jack
> connections for 12v at 10 a or greater, depending on the power supply
> you acquire.
>
> Everything worked great when I had it clipped together, the resistor I
> chose was showing 13.4 v on my DMM. Then I went to solder the
> connections and melted something down between the board layers which
> hosed the whole deal so it would barely turn the fan (used a small
> torch, should have used an iron). Now I'm out of peecee power supplies,
> but I know what to do and I saw it work. I will get a few more when
> convenient.
>
> If this isn't clear, I will either scan and email or mail you a copy of
> the article.
>
> Nice fan, too.
>
> BTW I took the 4" fan out of the bad unit and epoxied a radio shack
> slide switch to it to make an exhaust fan for the kitchen. I will mount
> it in the upper left corner of the driver's side window screen frame,
> marking and drilling the frame with three small holes at the mounting
> holes of the fan, and leaving the lower right hole cantilevered over
> the screen. I'll wire it into the light directly above it, behind the
> curtain rod so the curtain can slide. Just right for a sightly warm
> night, a day away from the car in the sun, or to exhaust the kitchen
> steam etc.
>
>   I don't have one yet, but for a cool light see Harbor Freight item
> 4274-0VGA.
>
> Jim
>
> On Thursday, December 4, 2003, at 08:09 AM, Gnarlodious wrote:
>
> > Entity Felder spoke thus:
> >
> >> My dad found a copy of a recent model airplane magazine that had
> >> explicit instructions for turning a peecee power supply into a 12V
> >> charger.
> > Can you send me a copy of that article, or turn me on to a webpage
> > describing the process?
> >
> > --Gnarlie
> >
> >
>