Converting AC to DC lighting?

[Timelord]

Originally Posted by Dr LuLu

So I am wondering if it is possible to use AC lighting for the skoolie??

I see that some lights have a transformer between the plug and the light socket. The transformer steps the voltage down from 120 to 12V. But some transformers also rectify the AC to DC. I read online that if the output is still AC then V is labeled as RMS. If that's the case, then I assume I could just wire the DC directly to the socket and eliminate the transformer altogether. That is... if in fact the socket is DC ready.
1. Am i thinking this through the right way?
2. How can I tell if the AC is also rectified into DC?
3. Has anyone done it?

The reason... the guy in the next campground is a contractor and he asked me if I could use these:
http://www.ikea.com/us/en/catalog/products/50119351

I have no idea... I really want to avoid wiring anything AC because I'd like to do DC as much as possible. I know I could always use an inverter... ugh... too much $$ right now and again, I just want to keep things simple.
Thanks!!

I've had trouble with those type of light fixtures getting quite hot, the fire danger enough to make me shy away from halogen in general for most indoor lighting applications. Ignoring this, your biggest problem is that the vehicle power is going to be reaching up to near 14 volts when engine is going, possibly even going higher. Actual vehicle accessories take this into account, the IKEA plug in item most likely does not.

You would need some form of voltage regulation to clip anything over 12v. This can be kludged for a certain amount of money, but with wiring, heat, and costs overall, I would personally suggest getting lighting built for vehicle power system from the beginning.

If you go the inverter route, what appears may well be easiest if not the cheapest option, you may also run into the problem I've had with some power supplies burning out in short order due to the stress modified sine wave puts on them.

[lornaschinske]

We run 12vDC low voltage "landscape" lighting in the RV along with the RV's 12vDV electrical lighting. We wired directly into the 12vDC wiring.

This is our "porch" light (4W light bulb... gives off a nice low light that doesn't blind us)

http://www.lowes.com/pd_95474-53027-...uantity_sold|1

I have 5 more inside the RV. We uses them for overall low level lighting plus more 12vDC for task lighting. All are wired directly into the RV's 12vDC system. We will be using similar for the Bus. The light pictured above also comes in Antique Copper which is the colour that we will use. I will install several of them as exterior lighting.

We stay away from halogens. David has installed them before and feel they get way too hot.

[Timelord]

Ooh. Very nice!

[lornaschinske]

Originally Posted by Dr LuLu

... do you have to alter the low voltage lawn lighting at all? I imagine you would have to remove the transformer and then just wire direct to the lights? That brass light looks super cool!!

We do not run transformers on the landscape lighting. The transformers are for AC to DC. Lights actually are 12vDC. I do not think our lights came with a transformer. These are the type of lights that you wire into a system that uses a big transformer. So many of the "deck" lights do not come with a transformer unless you are buying a kit.

BTW, that's not brass, it's copper. I want to paint the rub rails, mirror backs and all chrome/aluminum trim with the Rustoleum "Hammered Copper". It's not easy finding copper stuff. Everything is chrome, aluminum or brass! I may be able to use some "oil rubbed bronze" as some looks more like oxidized copper with worn areas on it.

[dirtygoat]

Awesome info... Love the lights...

Thanks...

[Redbear]

Incandescents, including Halogen, can use AC or DC. Florescents need AC, or a special DC circuit board that mimics it.

As Timelord said, the voltage on a vehicle system varies depending on state of charge, load, and any charging source. It can be as high as 15 volts, which might be 125% of what a lamp designed for a transformer expects.

But fear not! You can wire these in series pairs. This is a trick I sometimes use with exit light fixtures, so that the bulbs never burn out.

Take two of the Halogen fixtures, connect one wire from the first one to +12 volts and one wire from the second one to ground. Then take the unattached wire from each one and tie them together, insulated from both hot and ground. Each fixture will now get 5.5 to 7.5 volts instead of 11 to 15 volts. Each bulb theoretically gets 1/4 the normal wattage, although the resistance of an incandescent is supposed to change as it heats or cools. If the fixtures have attached switches, both must be on before the pair will light.

You will need more fixtures to give the same amount of light, but they will stay cool, and probably never burn out unless they suffer mechanical damage (potholes?). This scheme is not particularly helpful for task lighting, but having a row of glowing lights for area lighting can set a peaceful mood.

[Redbear]

Originally Posted by Dr LuLu

great info Redbear! thanks. Any idea how LED lights would work? There are LEDs made for DC but the AC LED lights are cheaper for sure. I really like the LED AC rope lighting you can find for a few bucks on sale after Christmas. For the same stuff, the LED DC rope light is $$$$.

Do you think your bulbs last longer wired the way you do? I like the idea...

All LEDs run on DC or pulsed DC - each individual "junction" runs on 2.1 to maybe up to 4 volts, depending on color. AC LED systems would have transformers, or a large number of LEDs in series with a current-limiting resistor. LEDs need a current-limited supply or they will 'pop' - and the quality of the current regulation directly controls the life of the LED - but LEDs are a whole 'nuther topic.

As I said above, if you put two IDENTICAL WATTAGE lights or fixtures in series (important point I forgot to make), each one will get half voltage, and therefore half the current, and half times half equals 1/4 the wattage, assuming a fixed resistance. Bulbs lasting literally 'forever' is a bit of a stretch, but I would be surprised to ever see them burn out.

Again, I forgot to make the point that unequal bulbs in series will not divide the voltage this way, because their resistances are not matched. For example, if you series-connect a 100-watt and a 25-watt bulb, the low-resistance 100-watt bulb would get only 20% voltage, and the high-resistance 25-watt bulb would get 80% voltage.

[Roachhill]

I haven't got as far as converting my bus but my log cabin runs off a 12volt battery system. In the cabin I have 12 volt DC CFL bulbs that screw into standard edison sockets. With those any standard light fixture becomes a light for your RV. While not the cheapest bulbs in the world it was cheaper than running out and replacing all my lights and now all my lights look like normal lights not some RV things. I know it doesn't exactly answer the question but I thought someone might find it useful info.