VCCA Home Forums TECHNICAL - GENERAL Electrical - 6 volt Here's a puzzle for you.

I converted the tail lights on the 38 to BA15D sockets so I could use 1154 bulbs with the intent to swap to brighter LEDs. I bought several brands of LED from different sources on line. All claiming certain Lumen levels much brighter than the 1154. I tested all of the bulbs in a separate socket and all but two work normally in that test socket, those two were internally wired backward and would work if I swapped the wires on the car (not going to do that). The issue is all but two of the LEDs don't work normally when plugged into the sockets on the car. The 1154s work normally in the car. Testing the sockets with my multi-meter shows over 7v to the contacts with the ground meter lead on the housing. The two LEDs that do work in the car are a tad dimmer than the 1154s, both by eye and by a Lumen app on my phone. The baffling thing is why do they all work OK in the test socket but not in the car when the sockets in the car test good? I tried running an extra ground wire to the socket housing just in case but it made no difference. For now I'll stay with the 1154 incandescent but my mind won't let go of the why they work in one socket and not another when all sockets test good and the 1154s work in all the sockets. Automotive electricity makes my head hurt....

The more I mess with LED's in any application (automotive or household) the less impressed I am. The 3 deficiencies I see are actual brightness, dimensional quality control, and life. It does not surprise me that you are observing less brightness than you expected. A big factor is the physical location of the light emitting element with respect to the housing. Most of the time the LED will be buried a lot deeper in the housing.

With respect to which bulbs work in which housing, I have 2 thoughts. One is that due to dimensional variations in the LED's your test socket fits the LED bulbs much better than the sockets in your taillights. The other is that due to the low current draw of the LED's they are more susceptible to resistance issues. In fact LED's do not have a linear voltage and current relationship over their full operating range.

Try polishing the contacts and the socket housing in your car to see if that makes a difference.

One other point to remember is that unless you add resistance to the circuit or go to a solid state flasher your turn signals will not work. The LED's will not draw enough current to make the thermal element in the flasher heat up to open and then cool to close.

No worries about the turn signals, my arm works just fine. I'll try cleaning the socket contacts and see if that helps. Two of the LEDs that don't work did work at one time then stopped so there may be something to that hypothesis.

did you use the same BA15D sockets in the car that you are testing with ?? make sure the bulbs are fully seated and rotate them 180 degrees in socket to see if it makes a difference. BA15D is a dual element socket depending on how wired in car, one lead feeds one element, other lead feeds other element. like low/high beam, or tail lights vs brake light. housing is ground as you know

how are you wired up on the test socket ?? you running 6v to both elements at the same time so that both elements are on at the same time, where as in car typically one or the other is on.

I did the same thing when i tested all the bulbs on my 1929. bought a BA15D & BA15S bayonet to do bench testing of the bulbs before install. When installed they are just as bright in the car as they were on the test bench socket. i used a red sharpie to mark the HIGH beam leg on the bulb so that i KNEW which was the bright leg/filament while on the bench.

The sockets in the car have a flange to facilitate mounting them in the housing. The test socket doesn't have the flange. I marked the brake light leg of the test socket with a length of red shrink tubing using an incandescent 1154 bulb to verify which is which.

I just got back in the house from fiddling with them some more. I cleaned, buffed and lightly wire brushed the contacts as well as the grounding lug paths using a dremel tool. No love. The brake light side of 4 of the 6 LEDs work but not the tail light side when plugged into the sockets in the car. The other two LEDs work fine in the car, tail and brake, but aren't as bright as the 1154s. The incandescent 1154s work fine in all sockets. All bulbs work OK in the test socket.

An interesting side note. With the park lights on to activate the tail light circuit, if I turn the LEDs around and insert them in the socket backward where the brake side contact contacts the tail light side of the socket the brake light side of the bulbs work.

One can say it's the sockets but two of the LEDs work fine in them while four don't. One can say it's the LEDs but they work fine in one socket and not the other two. It make no sense to me and I'm done beating my head against the wall trying to figure it out. I can still get 1154s and, with the inside of the housings painted gloss white, they're bright enough to do the job so that's what I'll live with.

do you have the specs on the LEDs you picked up, or where you got them from ? i wonder if they are 12v LEDs sold as 6v ? or those LEDs listed as 6-14V or crazy. i found out in my testing that they have to be TRUE 6v LEDs to work and be bright.

just an FYI i bought my LEDs from here: https://www.ledlight.com/6-volt-negative-ground-automotive-led-lights.aspx
great people, great service, and no issues. the link above goes to the negative ground 6v LED selection, they have some 1154 in there

attached are the bulbs that i have bought and tested, in socket and in car basic specs and info

some of my testing: https://vccachat.org/ubbthreads.php/topics/470314/

I bought between Amazon and ebay. Two types on ebay. Four bulbs from one seller (two of which are backward as noted above) and two from another. The two from a different seller are the only ones that work right but aren't as bright as expected. Two bulbs from Amazon.

These are the two that work: https://www.ebay.com/itm/165884366145

This is the set of four with two backward: https://www.ebay.com/itm/154223360934

The two from Amazon: https://www.amazon.com/gp/product/B079HSFXP4/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

I'm sure all were made in China. The interesting thing is the two from Amazon both worked for a while then the tail light stopped while the brake light side works. As mentioned both still work in the test socket.

question are the contact points on the bottom of the bulb round or oval ?? I have an issue with some that were round as the contact point it small and NOT perfectly spaced and line up with my American made vintage sockets in my car :) took a file and flattened them down some to create MORE surface area, also make sure they are FULLY seating and not sitting above the socket contact points, china defect in specifications and lining things up to fully contact and have pressure on them !!

so you are using BAY15D

BAY15D has 15mm socket and the Y for 2 pins are offset one deeper then the other from the connector end, only one way to install, D for dual element (2 power inputs)

BA15D has 15mm socket, and the Y for 2 pins are inline with each other, so you can put the bulb in 2 ways, 180 degrees out, D for dual element (2 power inputs)



first ebay bulb is a 6v-32v LED, Side directed so will need a good reflector to redirect the light forward (towards tip)

second ebay bulb 6v 150lm with 30 SMD elements, 8W is a lot for a little LED outputting only 150lm. not very efficient or bright

amazon bulb looks good specs wise 6v 450lm 1.8W, has 17 SMD elements, some facing around, some direct. would be more proficient in a non reflector application.


yeah think they ALL are made in china, even the ones i have :)


here is a super bright 1154 BAY15D 750lm tail 900lm brake, 60 LEDs 16 forward, 44 round approx 6W
...https://www.ledlight.com/bay15d-1154-6-volt-60-smd-5730-dual-filament-reduced-profile.aspx

wish i had some BAY15D laying around i would ship them to you to test and play with, all i have is BA15d and BA15s

Tiny,

I'm no help on your fig newton problem. Sorry.

It may be that the car is merely rejecting the new fangled LEDs. Besides, are't the 1154s bright enough to alert anyone driving behind you that you are there? They used to be.

Best,

Charlie