If you’re thinking about converting your RV lights to LEDs, or Light Emitting Diodes, you’ve found the right article to get started. The conversion is usually pretty quick & easy, rather inexpensive, and pays off big time.
This guide will hopefully save you a few hours of research, or at least help to solidify what you already know. I am not a professional technician, and will never claim to be. This guide is based on my research, experience, and – most importantly – mistakes.
Let’s get started:
Step 1. Figure out what kind of light bulbs you have in your RV.
The most common bulb is the 921. Some fixtures are labeled with their bulb info, but you can usually just remove the bulb and find the size printed on the bulb itself.
Although 98.9% of my bulbs are the 921 size, I do have three bulbs around my 5th wheel trailer that are other sizes: The bulb in the refrigerator, a bulb outside and under the gooseneck, and the 3rd bulb is in the overhead ceiling fan fixture, which runs on 120VAC (house power) rather than 12VDC (battery power) anyway. I probably won’t convert any of these.
Step 2. Count your bulbs.
After you know what kind of bulbs you need, figure out how many you currently have, or at least how many you want to replace. I recommend replacing entire sections at a time so you aren’t mixing the lighting, which can be an eye-sore – but that’s just me.
You might want to walk around the inside and outside of your RV several times to count the bulbs. I probably counted mine 10 times, at different stages of my conversion research, and I usually got a conflicting number each time. Since my conversion, I’ve found 2 more bulbs that I forgot to exchange. (Whoops!)
Quick tip: Order extra bulbs. They are handy when you discover a new fixture, find a bulb you forgot to convert, or if a bulb gets damaged or becomes otherwise inoperable.
Step 3. Search for your replacements.
If you’ve already started shopping around, you may have noticed that there is a string of letters and numbers associated with each type of LED light, like this one:
**This is just one example. There are many like it, but some are completely scrambled. After decoding this example, you should have enough knowledge to decode just about any product listing.
The first letter/number combo – T10 in our example – is going to indicate the size of the bulb’s base. 921 bulbs have a wedge base, and most RVs use the T10 size, but will accommodate T15. You may come across a code with ‘T10/T15,’ which means it will fit either. T5 is a slightly smaller base, so make sure you know which one you need.
The second number in our code – 921 – is the size of the bulb the LED will be replacing. For example, if you have a 921 incandescent bulb (as pictured above), you will want to look for LED lights that start with this number. I you have a bulb that is not a 921, look for the bulb number you need to replace.
Side note: when searching for LED replacement lights, there may be additional numbers listed. These are usually other compatible bulb sizes.
The third number – 13 – is the number of LED panels that are on each bulb. The number of panels will be one of the factors determining bulb brightness, or in industry terms, Lumens.
Incandescent light brightness is commonly measured in energy, or watts, whereas LEDs are measured in Lumens.
So, a little math is involved in figuring out how bright an LED bulb will be compared to the original incandescent bulb.
By dividing the lumens by watts, you can find how many lumens are in each watt:
1600 lumens / 100 watts = 16 lumens per watt
Lumens and watts are two different kinds of measurements, so there will be a slight deviation in lumens from lower wattages to higher wattages (approx. 12.5 – 17.5 lm/W). Rapidtables.com has a great scientific explanation and boils it down to approx. 15 lumens per watt.
921 bulbs use approximately 18 watts (from the label pictured above), so the luminous output of an average RV bulb (18 watts x 15 lumens) is about 270.
Now that we have identified the brightness of the 921 bulb, it can be compared to the measurement of an LED bulb. More on LED brightness next.
The fourth number – 5050 – is part 2 of how we factor LED brightness. This number represents the actual size of the individual LED panels. 5050 translates into 5.0×5.0 millimeters.
Panel size is directly related to luminous output. Smaller panel = less light, and vice versa.
When selecting replacement LED lights, compare the number of panels with the size of each panel to get an idea of how bright the light will be. It’s not an exact measure of brightness, but it helps to distinguish between different LED bulbs.
For example:
- A bulb code that states 42-2825 (42 panels, 2.8×2.5mm in size) would have 294mm2 of light emitting area.
- A bulb stating 24-3528 would have 235mm2 of light emitting area.
- And the bulb in our example, 13-5050, would have a total area of 325mm2.
SMD stands for ‘Surface Mount Device.’ On an SMD bulb, the diode is mounted on the surface of the circuit board. This type was pretty standard in my research, but you may run across these other types as well:
- COB, or MCOB, stands for ‘Chip (or Multi-Chip) on Board’, and these are more powerful lights.
- DIP, or ‘Dual Inline Package’, provides only low light.
The final piece of our example code, 12V – 28V, represents the range of voltage the bulb can handle.
A common miscalculation is to think that RV 12VDC is actually 12 volts. In reality, the 12VDC system can range between 11.6 volts, when a battery is 80% depleted, all the way up to 15+ volts if in a charging state.
When selecting an LED replacement, I recommend choosing one with a wide voltage range, like in our example. Some bulbs will only be rated to handle 12V; those bulbs will not last very long in your RV, will be dimmer at lower voltages, and may overheat under higher voltage.
Step 4. Pick a color.
LED color is measured in Kelvin.
Unless you want red, purple, or other special color, you’ll most likely be looking for white LEDs. There are three basic options:
- Bright White, >5,500K
- Cool White, 3,500 – 5,500K
- Warm White, <3,500K
For comparison sake, incandescent light bulbs are around 2,500 – 3,000K. I wanted as close to Incandescent color as possible because I like the warmer light compared to the brighter white, so I chose the warm white option.
Important considerations
- While searching for LEDs, you will probably find a mixture of vehicle headlight options. Unless you are trying to scare a deer out of your trailer, stay away from these. They will normally be 7,000+ Kelvin, have extremely high Lumens, and are sold in sets of 2.
- Physical bulb size. This is especially important in confined areas. With the bulbs I purchased, I could not replace the incandescent located above my cooking range without bending the metal, so the bulb could fit under the grease protecting cover.
I hope you found this guide valuable, and I wish you the best of luck in your RV light conversion. Comment below to ask questions, or share your conversion story!
Here are some pictures and stats of my conversion:
I chose an economical LED option from Amazon, rather than going with a more expensive version, saving $200. So far after 2 months of use, all the bulbs still work and I haven’t had any problems.
The bulbs I used were coded like this:
921 27-5050 SMD 10V-24V, Warm White (3000-3500K)
These bulbs are quite a bit brighter than the older ones, but the value brands are more limited on options. I would have preferred more incandescent-similar, or even dimmer LEDs, but these are okay. I do prefer the energy savings, and the fact that these bulbs don’t immediately get blazing hot.
Safe travels!
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