Date: Sat, 6 Dec 2003 13:47:32 -0500
Reply-To: EMZ <vw4x4@FYI.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: EMZ <vw4x4@FYI.NET>
Subject: Re: Making a 12v battery charger from a peecee power supply
In-Reply-To: <BBF6BD07.2D14A%gnarlodious@earthlink.net>
Content-Type: TEXT/PLAIN; charset=US-ASCII
Exactly what I mean. Switcher or not the net resault is exactly the same.
In this insance there is absolutly no reason for a swithing power supply.
Way overly complicated...
Eric 86-VW4x4
vw4x4@fyi.net 86-SS Syncro
Pittsburgh, PA USA 1936-Chrysler
92-Jetta GWC
www.fyi.net/~vw4x4/vw4x4.htm
On Fri, 5 Dec 2003, Gnarlodious wrote:
> What Felder failed to mention is that this is no ordinary battery charger.
> This is a "Switched Mode" Power Supply. It doesn't have the huge heavy
> transformer but uses a small light transformer running at about 40kHz to
> transform the current.
> The frequency is controlled by a PWM chip that regulated the input and
> output by using Pulse Width Modulation. This means input voltage can be
> anywhere between 80 volts and 240 volts. No transformer overheating buzzing.
>
> A switching charger normally costs about $270, Felder is saying you can do
> it for about $25 if you're willing to play.
>
> -- Gnarlie
> http://www.Gnarlodious.com/Vanagon/Electrical/Pages/Bay.html
>
>
> Entity EMZ spoke thus:
>
> > Man do you guy love to over complaicate things. Power supplies for
> > batteries are very easy to build. All you need is a transformer
> > bridge rectifier and a capacitor. Yuo don't even need to regulate it.
> >
> > Eric 86-VW4x4
> > vw4x4@fyi.net 86-SS Syncro
> > Pittsburgh, PA USA 1936-Chrysler
> > 92-Jetta GWC
> > www.fyi.net/~vw4x4/vw4x4.htm
> >
> > On Fri, 5 Dec 2003, Felder wrote:
> >
> >> 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
> >>>
> >>>
> >>
>
>
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