The 921 LED Reverse Light Bulb Study

No offense but this is exactly the kind of "review" I am ignoring. Zero solid information especially when trying to decide between different LED bulbs. Give me the "actual" numbers and I will be happy.

 

mkay....I don't really care. I wasn't doing a review....I was just telling anyone that wanted to read that I like what I bought. If I but in a bulb and it's way brighter (to my eyes) than the OEM bulb then I'm going to go with it.

 

Just to expand on this since this thread is a good reference for it.

Some manufactures are up front about the actual lumen output and this gives us a good reference point for just how different "raw" lumens and actual lumens can be in a basic LED bulb without considerable thermal design. As an example J.W. Speaker actually does usually list both. This work light has a "raw" lumen output of 2450 lumens but an effective lumen output of 1350 (see the numbers on the PDF datasheet). So ending up with half the advertised lumen output is not uncommon - but some manufacturers are honest about it.

It also comes down to the LED manufacturer as well. Many LEDs are rated at 25*C which is of course not at all the temperature they are run at. Some manufacturers though (Cree is one) rate at the more typical operating temperature of 85*C. Thus if a bulb manufacturer just copies the "raw" numbers from an LED datasheet the Cree sheet listing 85*C output is going to be closer to the actual output than LEDs that are rated at 25*C.

With LEDs it is all about thermal design. If a bulb has a bunch of chips slapped on a circuit board with no metal to be seen you should probably expect to derate the raw output by a factor of two or three. If the bulb has actually been designed with a heat sink it is likely to be able to output closer to the "raw" output. Best of all would be manufacturers who actually publish an effective rather than raw output number.

As a last note you can find some lights that really do run nearly at the raw numbers but usually those have very complicated driver and thermal designs. Most Baja Designs lights run at the maximum rated output of the LEDs and also have a thermal protection circuit in them to reduce output if the LED begins to overheat. But these are integrated light assemblies - not just bare bulbs like we are talking about in this thread.

 

One example of BS data is the bulb I got of ebay:



Actually measured current was 0.3A, so the total power of the bulb is 3.6W (including power loss on bridge rectifier and CANBUS resistor. The actual lumen output was close to 250 lumens not 800.

For that I requested a refund for power and lumens I paid, but didn't receive. And I got 50% refund from the seller. Still rip-off (I should get close to 70% refund, but I let it slip).

 

I just measured electrical of this bulb. The bulb takes 0.36A at 12V so the bulb takes 4.3W. Because it has high efficiency "buck type" driver and low voltage drop rectifier bridge the publish spec of 4W appears to be true. The lumen output is different story. I don't know what LED chips are used in this bulb, but the average of high efficiency white LED is between 100lm/W - 70lm/W (the highest efficiency I saw is 130lm/W but not in that chips). So I can assume this bulb gives out between 300 and 400 lumens.

So far this is the highest output I saw of relatively cheap T15 LED bulbs (I did not have a chance to measure DeAutoLED 921 LEDs bulb so I can't tell how this one stands). VLED shown by DVexile are superior, and for LEDs freak like me it is good deal. When I have a chance I will look into VLED for my 4Runner.

 

When I bought the bulbs they were actually advertised as 18w, 1000 lumen. When I wrote this post they had revised it to 4w but kept the 1000 lumen rating.

I've got the VLEDs to try out, hoping to get around to it this weekend.

 

The set of 2 I bought on Amazon 4 weeks ago for $12.99 (now it is for $11.99) is described as 5.5W and 1000 lm. I will correct it in my Amazon review soon .

I just checked Lumiled datasheet for 4014 LED chips. This 1000lm published confirms what I wrote before. Datasheet shows 23lm at designed 60mA. Times 45 led chips in this bulb gives you 1000lm.
However the efficiency of this chip is between 130 and 150 lm/W. So the bulb at 4W (4.3W total minus 0.2W at Diodes and 96% driver efficiency) is probably giving around 500lm for sure less than 600lm.

The plus is uniform led placement which gives nice light pattern in reverse light fixture.

Edit: Now the review is on Amazon https://www.amazon.com/review/R32SDAMH7IYB6T/ref=pe_1098610_137716200_cm_rv_eml_rv0_rv

 

Awesome write-up.

 

Excellent write up! One of my reverse lights went out so I went to Home Depot and found a Phillips 35W HIR. I couldnt get it to fit in there tightly and ended up chipping some of the glass. I'm returning the unused one and already purchased the DeAuto LED.

 

They are tricky to fit snugly, and many run into that problem which is why I put together this alternative thread. But for clarification the 35w Gy6.35 bulbs you picked up at HD were not HIR. Those are standard halogen and much weaker than the lower wattage and cooler running HIR version, the 35w halogen put out 420 lumens while the 30w HIR put out an astounding 750 lumens. Hence my strong recommendation for HIR over halogen.

 

Ahhh, gotcha. They are definitely hot! Bulb didnt turn on at first, so I wiggled it and it flashed on for a split second and burnt the crap out of me. That's when I decided to go another route, lol.

 

I installed Deautokey leds on my new tails. Bright as day one. No bulb out warning. No flickering.
Day one was 2014, bulbs were for my 2012 Jetta. These bulbs last and last. They just keep on shining bright.
Deautokey has some of the best customer service dept I've ever dealt with.

 

Really? No one's said it yet? Do I have to be "that guy"???



.......this write-up has been really enlightening.......

 

Thanks for the help. How do you think the jdm Astar compares to what you tested? I put them in side by side with the stock and they are definitely brighter and similar full spread of light around rear of truck

 

The JDMs look identical to the DeAutoKey bulbs, and I suspect they are the same. It is not uncommon for several different vendors to label a bulb as their own when they come from one manufacture. That said the 800 lumen rating is complete BS and typical of LED vendors who advertise theoretical output when actual output is about half.

 

I have the DeAuto reverse lights and they are incredibly bright and shine light everywhere. I have no experience with the JDM reverse lights, but I do have JDM bulbs in most of the other locations in my truck. JDM has been great to buy from and I have been very happy with all the bulbs I have bought from them.

 

Damn, I wish I read this before I bought $45 dollar reverse lights from Jumper lol

Edit:

Mine just came in and look like this. 5 cree LEDs, 4 around the housing and one in the center with a glass lens.



I'm excited to see the output especially since one with this type of design was not used in this test.

 

I have a similar one from Vleds to try out and add to the test, but I currently have way more projects than time.

 

I have a concern in reguards to the HIR bulbs, one downside to incandescent vs LED is heat generation, have you had any issues with the socket or housing melting with the HIR? Any blistering of the exterior plastic lens? What is the longest you have burn your lamps? Woulb be curious to see if they cause issue burning for an hour or more.

 

All the info is in my HIR thread including temp readings after leaving the truck in reverse for 20 minutes. HIRs run much cooler than their halogen output equivalent, it is just warm to the touch. Zero issues with lens or housing.

https://www.tacomaworld.com/threads/gy6-35-hir-921-reverse-light-upgrade-vs-high-power-leds.474996/