DIY Dual Voltage Lighting

Here's a handy project - 120VAC and 12VDC lights in the same fixture. And it's easier than you might think!

When we bought our boat it had dual voltage lights, but we didn't really like them. They were huge and the style didn't really match ours, and most of the light lens was covered with metal, so light only came out the top+bottom! Very dumb design, but they are dual fixtures, with a regular 120VAC socket, as well as a G4 12VDC socket. It wasn't until I decided to convert some lights myself and was removing the old lights when I discovered the old ones were DIY projects too! So obviously I'm not the first to think of this, but if I had noticed that the old ones were self-converted it would have saved me some time. I spent a bunch of time and effort trying to find replacements that were dual voltage from the factory, and I wasn't having much luck. Now I now why!

Original lights:

1. Go to a good lighting store and find some outdoor 120VAC lights you like and which have room for a socket and light. I didn't like what the local home improvement stores had, but a local lighting store had a great selection to choose from.

I already decided on using Sensibulb LED modules (which I had in the old lights). These modules are large (but great and only draw 160mA, 1/12th as much as the old halogen lights! More on LED modules later) - so needed to make sure the lights had room for them. The modules had to fit in the lights, with room for the 120VAC bulbs as well. Think about shadows and how the lights will affect each other. I also think choosing outdoor fixtures makes sense for the marine environment as they are better sealed and protected from moisture.

We choose incandescent for the 120VAC side, since they are on a dimmer, but also the standard fixtures were about 1/2 the cost of fluorescent, and we won't use them except at the dock anyway. Even if you want more energy efficient bulbs, it makes sense to buy the cheaper fixtures with standard sockets that you can buy bulbs anywhere for, and then just put in fluorescent bulbs.

Think about how and where you will mount the lights. I was fortunate in that the footprint of the new lights was smaller than all the holes from the old lights (even though they were much bigger), so I didn't expose any holes in the bulkhead. I was also able to use the mounts the lights came with, but that may or may not be possible - it just depends on your lights and where you are mounting them.

2. Drill some holes into your brand new fixtures and render them non-returnable and void the warranty! I used the G4 sockets from the old lights because I already had them, and they are what the Sensibulbs use. Drilling the holes was the hardest part of the project! The metal on our new lights was pretty tough stuff, and it took some time to drill through them. It doesn't help that my drill bits are cheap and dull... From there it was a simple matter of bolting them in with some stainless hardware from Home Depot or wherever.

3. Solder in the 12VDC bulb sockets and attach them. Electrical isn't a problem for me, so this went quick. Use some heat shrink to insulate the connections, as well as where the wires come through the hole to assure no short circuits! (It's not obvious in the pictures, but on one fixture I used clear heat shrink and the other I used black).

Then mount up the lights:

You can see the G4 socket in the picture above just to the left of the 120VAC light bulb. Or in the picture below, to the right of the bulb.

Other side, with Sensibulb LED module installed:

That's all there is to it! Overall I'm really happy with how they turned out. The new fixtures are not all that large, so the LED modules are pretty close to the 120VAC bulbs. This results in some shadows. Also the modules are a bit close to the curved part of the glass, so the light output is a bit inconsistent. But all in all we are really happy with how they turned out - the lights are considerably brighter than the old ones since most of the light isn't covered with metal!

A few comments about Sensibulb LED modules. LEDs are really great, but you have to be careful. There's a lot of really, horribly crappy LEDs out on the market. I have one from West Marine that's a very harsh blue light and nothing more than a nightlight - completely useless as a replacement for halogens. There's probably some other good products out there, but I'm really impressed with the Sensibulb LED modules. They have a very warm and wide output, and only draw 160mA - compared with the 2000mA the old halogens drew - just 1/12th the energy!

I think the following are all important things in selecting LEDs:

1. Power consumption. Any LED is going to use less power than an incandescent, a halogen, or a fluorescent. Considerably and measurably less.
2. Light output. You need a light that's bright enough to be useful. This is harder than it sounds, many LED lights are just not that bright.
3. Color temperature. Many LEDs produce a harsh blue light, but you can find some that have a much warmer temperature similar to incandescent lights.
4. Light angle. Some LEDs have a very narrow angle of output, which doesn't make them very good for general lighting.
5. Cost. Don't be fooled by the cheap but crappy bulbs and modules. The good ones aren't cheap, but they should last for years, if not a lifetime of use.


OpenCPN - Open Source PC chartplotter software

OpenCPN is a really neat project, and worthy of a post on any cruising blog... This is an Open Source and completely free PC chartplotter software solution supporting lots of features, with new features being added constantly.

Currently, OpenCPN supports BSB3, S57, and CM93-2 chart formats. It integrates with any NMEA0183 GPS source, and supports AIS. Take a look!

This project is well worth supporting - go download it today: http://opencpn.org

Another related, and useful utility is navmonpc, available free from http://www.navmonpc.com/. The combination of both these utilities makes for a really great navigation solution, with NavMon consuming all NMEA0183 sources and creating a virtual serial port for OpenCPN.
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