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RV LED Interior Lighting experiments for energy savingSaturday, August 15. 2009 In an attempt to make our battery last longer on dry-camping expeditions, I measured all the electrical loads we have and found that the biggest appliance we have is the lighting system - and the Sunline has 15 interior light bulbs, not to mention outside lights all over the place. All the bulbs are 921 (spade type) and at 12-13v they consume at least 1.3A each. That's easily 18 watts. That's each! If we have, say, 4 of them turned on, that's over 5A - over 100Ah in a 24 hour period! How big is your battery?So that was no good. There are two alternatives - compact fluorescents and LED's. I've tried LED's before, but the color temperature was horrible - very cold and white, bluish almost. They are very efficient though. As for CFL's, the idea of running something that will only glow at several hundred volts from a 12V system just doesn't sound efficient to me, so I looked into what's been happening with LED's these days. I was pleasantly surprised... ShoppingTurns out that you can now get a variety of LEDs and complete bulbs/assemblies in a color spectrum called "warm white" - and so I ordered some 3x4 LED boards from china (ebay). For about $8 each, you get a universal bulb, provided you have the room for a flat circuit board, with a bunch of connectors for just about every automotive bulb socket. LED Bulb assembly and some of the adapters I got 6 (they aren't 99 cents after all) to see how well they work. PerformanceFirst of all, they run at about 350mA @13v, or about 4.5 watts. They are advertised as 2.5 Watt bulbs but I'll have to disagree. Still, that's 4-5 times less than the originals, so it's a pretty good start. To my great surprise, they run really hot. So hot, in fact, that the 3M double-stick tape they come with melts off the surface in about 1 minute. I've never seen hot LED's before, but I guess these 5050 SMD chips are not the usual type. In order to situate them in the standard RV bulb enclosure, I zip-tied them to the flat reflectors (which are more than large enough for the purpose). The zip ties do not appear to be melting. When installed this way, the lens is somewhat cooler with the LEDs than it is with the incandescent bulbs. As for the light intensity, it's kind of hard to describe, so I took some pictures. They are definitely less bright than the stock 921's, but just how bright is hard to measure, because they are a somewhat different color temperature and are much more directional. Here is the light fixture. Led bulb is on the left.  LED vs Incandescent And here are two photos of the illuminated area, taken with an SLR with all settings fixed. Left is incandescent only, right is LED only (single bulb for both). The area is directly underneath the double fixture.  LED vs Incandescent - illumination SummaryIt is safe to say that the bulbs provide "adequate illumination", in fact you wouldn't want to look at it directly, even through the plastic lens of the fixture. The light is more directional and fails to reach quite as far laterally, but that is expected. I installed 2 for general illumination, 2 as reading lights over the table and 2 as reading lights over the bed. The color is certainly warmer than the typical "ultra-bright white" that I've gotten from superbrightleds.com in the past... but it's no incandescent. If you don't have a reference point (you only turned on an LED bulb) you would be OK with it. If you see them side-by side, you'll want the incandescent back on. In fact, I find that turning on a few LED's and one incandescent provides a very pleasant compromise - the warmth of the single bulb compensates quite nicely. When power saving is not an issue, I do prefer the old bulbs and use them instead. Trackbacks
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