DC without a fancy converter

[les45]

On my newest project I want to keep my electrical system simple. I will not have a battery since we always camp where there is AC campground power. I will obviously have an AC inlet with breakers and outlets, but I still want a simple DC system for lighting, vent fan, and USB outlets. Has anyone gone this route and, if so, what kind of transformer or other device did you use to provide DC power?

[kayakdlk]

I used a Battery charger /tender that has a 12V 5amp output. I used it to power all of my lights, fan, etc. until I eventually added a battery and then used it to charge my battery when plugged in. I cut off the 12 V ends and wired them to terminal strips off my fuse panel.

[Jim.Johnson]

A regulated 12v power supply like you would use to power a CB or Ham radio. Check your amperage needs for the things you plan to power and find a supply that is adequate. Battery chargers will usually have sensor circuits that change the output determined by the battery status. BTW most "12v" supplies put out 13.5v. That is the normal output of a battery.

[les45]

[quote="kayakdlk"]I used a Battery charger /tender that has a 12V 5amp output. I used it to power all of my lights, fan, etc. until I eventually added a battery and then used it to charge my battery when plugged in. I cut off the 12 V ends and wired them to terminal strips off my fuse panel.

That's the kind of gadget I'm thinking about. Do you have a specific make and model that you used? Most of the tenders I see online are trickle chargers with 1 Amp or less. How hot do they get? Any need for a cooling fan?

[DrewsBrews]

I'd stay away from using a battery charger like that. They aren't just a simple power supply that outputs a steady voltage. They actually monitor the current and change the voltage output in order to properly charge a battery... In fact charging a battery requires voltage to be even higher than the battery voltage to push the current "backwards" through it.. Often up to 14.5v. Many simple devices may handle it fine, but more sensitive equipment may have it's life shortened.

If you happen to have an old PC lying around those power supplies can be used. 12v is regulated at true 12v and they also output 5v for direct USB power without needing conversion. Whatever you use you will need to total up the draw of each item to get a maximum number in order to know what the power supply will need to handle.

[H.A.]

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[Shadow Catcher]

You may well find that at some point you wish you were set up with a battery and converter. There are far too many really great places to camp that do not have 120AC and there have been a number of occasions where we ended up in tent spots because that was all that was available. However a computer power supply may be the best choice if you wish to go that route.

[dmdc411]

I used a desk top computer power supply. It puts out 12(+)vdc @14amps max. I used all LED lighting, and a Fantastic fan. With 4 interior LED lights, 2 porch lites with LED replacement bulbs, currently draws 7.5 amps with the fan on high. The power supply has a circuit for a remote switch for turning it on and off. You tube for instructions on how to do combining of power supply circuits. It's easy!!

[les45]

I decided to go with the computer power supply since I had several old desktop PC's sitting around in retirement. They use a 250 watt power supply that is rated 14 amps at 12 volts DC. It is really a simple process to convert one of these to a DC power source. There are about 30 wires coming out of the unit and all the black wires are grounds. The +12 volt wires will all be the same color (in my case they were yellow). There is only one green wire and it is used to turn on the power supply. All the other wires carry different voltages. The whole conversion concept is to bundle all the black ground wires together and all the positive 12 volt wires together and use their collective capacities for the 12 volt power source. The green wire is paired with one black ground wire and can either be permanently connected or run through a switch. I will run mine through a switch when I install the system. All the other wires are clipped, taped, and abandoned. I added about 3' of #14 black for ground and red for positive wire to give me plenty of room to arrange my circuit layout later.

Wires are clipped and segregated


Green wire paired with one black ground wire will be used to turn on the unit.


Unused wires are bundled and abandoned; black (-) and yellow (+) are stripped and ready to splice.


#14 black (-) and red (+) leads are spliced, soldered, and taped.


It works!

[RonS]

If you're only camping where power is available, and aren't putting a battery into the camper, why bother with the extra complexity of 12V? Everything you want to run is available on 110V, even AC outlets, with built-in USB outlets....

I'd just do the entire thing in 110 AC and not bother trying to covert anything.

[kayakdlk]

Battery Tender 022-0157-1 , Shop around as the price various a lot. Never had any issue with any 12 volt device I have plugged into it

Dan

[les45]

If you're only camping where power is available, and aren't putting a battery into the camper, why bother with the extra complexity of 12V? Everything you want to run is available on 110V, even AC outlets, with built-in USB outlets....

I'd just do the entire thing in 110 AC and not bother trying to covert anything.

The pop-up roof ceiling is already wired for DC lighting and I plan to install a Fantastic Fan in place of the old AC unit. Looks like six of one/half dozen of the other. Using the old power supply looks like the cheapest way to go.