921 bulb replacement information can be found in this short article.
I've actually installed these replacements in my RV and can truly speak about them truthfully.
So please take advantage of my experience – for example – you can't ignore the lumens value!
The light bulb we are trying to replace is called a 921 light bulb with a “wedge style base”.
Here are some 921 bulb specs that you might find interesting. This bulb runs on 12 Volts DC (all/most RV systems operate on this system).
This 921 bulb in the wedge style consumes about 18Watts of electricity. I'm thinking this puts out about 280 lumens (hard to find GOOD data on this). So the efficiency of this type of bulb is 15 Lumens per Watt, which is fairly low for an incandescent.
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18 Watts doesn't sound like much, but when you are boondocking and running 10-15 lights you can consume 200 Watts which will drain your battery fairly quickly.
How incandescent lights work – very very simple explanation
For the technical person the way the incandescents work is that they heat a filament in glass bulb and the filament will then radiate light from the heated filament. Since energy is comprised of BOTH heat and light and the 921 bulbs get VERY hot, common sense will tell you that this large portion of heat is simply wasted energy. Or worse, in the summer, it will make your air conditioner work harder.
How LED lights work – very very simple explanation
LED lights work VERY differently. Without getting too technical, the way the material is constructed causes an interesting microscopic (actually smaller still) structure. When electricity is applied to the structure, the electrons “jump around” in such a way that they will emit a photon of light. Since there are zillions of electrons working hard there are zillions of photons which means lots of light for you. The SUPER COOL idea is that this really does not cause any heat to speak of.
RV52.com editor explaining in his own words more on LED lights
RV52.com articles on LED lights and more:
- Why are RV LED Lights more efficient than other types?
- Watts is the WRONG measure of brightness for RV LED Lights
- LED Lighting is different than incandescent: The angle of light
- RV LED Light Fixture Replacement with Dimmer
- Replacing RV Light Fixture for Incandescent with LED Light Fixture
- comparison of bright white or warm white led lights
- The Final, well final for now, RV LED Light selection guide
The application I FIRST tested the LED replacements is pictured here. Notice that any light only needs to send out light in a half circle (180 degrees) :
Acceptable led light replacements for rv lighting 921 bulb wedge style
- superbrightleds.com – WLED-WWHP10-DAC : $14.95 each : this WARM WHITE color tone LED light is almost a perfect replacement for the 921 wedge. There were two 921's in the fixture and I replaced it with two WWHP10-DAC's. So you can see I replaced about $3 of lighting with around $30 of lighting. I still think it is cool. I can tell you that the LED color tone is VERY VERY close to the 921. Also I can tell you that I think the WWHP10 was just slightly brighter and the color tone was actually just enough whiter to illuminate the area a little bit better. I was very pleased. The specs say the LED light bulb would put out 98 lm. I'll follow up on that later and verify. The current draw is 0.2 amps so the total power consumed would be 2.4 Watts. ASSUMING that my eyes are NOT lying when I say this is equivalent to the 921, we can probably use 280 Lumens as the reference, then the efficiency of this bulb would be near 116 lumens per watt. I don't understand how the mfg got 98 lm / LED in their specs? But I'm pretty impressed overall.
- ledtrailerlights.com – T10 Wedge 380 : Another warm white bulb, but arranged for 360 degree light. Puts out 380 lumens and it fully replaced another 921 application. These are $17.95 each, but have many more LED's on the ‘bulb'. Significantly brighter than the 921. WE highly recommend.
- I've used these
GRV Disks
copiously in the Tiny Texas Tumbleweed. They come in big bags so I expected one or two to fail, but for me, repeat – just for me, I did not get a failure. I'll buy these again. By the way, the brightness comes from how many of the little squares (called LEDs) that are on the disk.
As I find out more decent replacements, I'll list them here. Marlan
I have tried to make finding LED lights easier on Amazon.
I spent LOTS of time on this selector guide. It is FREE and costs you nothing and SAVES you time!
LED wedge lights RELATED listings from Amazon
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Don Reynolds says
Thanks. I didn’t know working with LED’s could be so easy. I’m going to order a couple of these things and try going Green. Thanks RV52.com!
rv king says
Look at home depot for the phillips accent LED for landscape they work great!
Neil says
I would like to replace the rg921 with a bulb that is not as bright. These things are blinding!
Any ideas?
Marlan at Rv52 says
Usually… people try to get their lights BRIGHTER not dimmer! So you are a bit contra-trend. If I use 280 lumens, a measure of light output, as my benchmark for brightness – then this LED light is only 220 lumens. So this is ONE way you can go – http://amzn.to/2tzNCL7 – there is only one review and it was a 5 star so you know that is bogus.
Here is a highly rated light fixture with LED lights in it and each side has a switch. That may help since most RV light fixtures seem to have both sides turn on with a single switch – http://amzn.to/2t0FExy
A BETTER strategy might be to find a dimmable RV LED light fixture – http://amzn.to/2t0wilE – this one seemed fairly highly rated. I wonder is it too darned hard to make a dimmer fixture!!! Probably not very popular I guess.