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    Using LED bulbs and avoiding check lights

    I've added LEDs to all of the tail lights including the license plate bulbs. Can anyone tell me specifically where to insert the resistors or how to otherwise disable the bulb check? I have the wiring diagrams but calculating resistance or hacking the check control relay is a bit beyond my skill level.

    The turn signals were easy to fix using a solid state flasher relay.

    Thanks!

    #2
    See here:

    Comment


      #3
      Resistors are a poor solution. You're just wasting energy. LED bulbs have a nice benefit, I've accidentally left my lights on over night, and had no issue starting the car in the morning the next day. If you stick resistors in to fix the check panel, you don't get this power savings.

      The real fix, as shown in AndrewBird's link, is to rewind the reed relays. Ignore the red wire jumper, that shouldn't be added.



      I did this on my touring. The brake coils, A, needed about 150 turns each, for my 5W LED bulbs to not trigger check errors. Stock was around 20 turns. I used 26 AWG magnetic wire.

      I did not have to touch the other relays, as long as my lights are not on while starting the car, I don't get a check indicator.

      Comment


        #4
        I was just thinking about this the other day.

        the real downside of LED bulbs is that they all suck....still. If you manage to find a pair that works...they will half their brightness in 2-5 years. It's a real race to the bottom on LED stuff. And I don't trust 90% of the suppliers.
        Originally posted by Matt-B
        hey does anyone know anyone who gets upset and makes electronics?

        Comment


          #5
          My experience with LED replacement bulbs as rear plate lights is that instead of lasting forever, they actually stopped turning on, flickering and burn out faster. If you live with the bulb out warning illuminated, you'll never know if they fail unless you look which could result in a ticket. For these reasons, I just went back to new incandescent bulbs. This was a few years ago though. Hopefully the tech and quality have improved.
          "I'd probably take the E30 M3 in this case just because I love that little car, and how tanky that inline 6 is." - thecj

          85 323i M TECH 1 S52 - ALPINEWEISS/SCHWARZE
          88 M3 - LACHSSILBER/SCHWARZE
          89 M3 - ALPINEWEISS II/M TECH CLOTH-ALCANTARA
          91 M TECHNIC CABRIO TURBO - MACAOBLAU/M TECH CLOTH-LEATHER

          Comment


            #6
            Originally posted by george graves View Post
            I was just thinking about this the other day.

            the real downside of LED bulbs is that they all suck....still. If you manage to find a pair that works...they will half their brightness in 2-5 years. It's a real race to the bottom on LED stuff. And I don't trust 90% of the suppliers.
            The last year or so has changed the market. Mostly due to strip LED lights taking off. You have a lot of LED makers providing high quality chip LEDs, with pretty impressive efficacy, which these incandescent retrofit manufacturers also make use of. You don't have to drive the bulbs as hard anymore to get good light output.

            This is one of the sets I'm currently using: https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

            They're pretty well made, it takes an extremely expensive pick and place machine to pack chip LEDs that tightly. They also use a constant current buck regulator, not a resistor ballast, so there's very little waste heat.

            We'll see how long they last. I see no reason why they would lose their brightness after less than 5 years though. Even the cheapest white LEDs have an LM80 rating of 30,000 hours. If anything, I'm expecting them to just outright fail, not to lose brightness.

            I didn't have a good way to accurately measure brightness at work, just a photometer and a cardboard box, but they were a little more than twice as bright as a 20W incandescent bulb. Input current was 480 mA.

            Comment


              #7
              Originally posted by earthwormjim View Post
              The last year or so has changed the market.
              Negative ghost rider. I'll believe it when I see it. LEDs are still a "race to the bottom" in price and quality. It's to the point that even cree is failing at some of their products.

              Case in point....A LED should last 100,000 hours - or so says general knowledge. I see a lot claiming 30,000 hour for car LED's. That should last WAY more then 2-3 years. It should last longer the the steal the body of the car is made of.

              Maths: You drive 2 hours a day to work (that's a lot) and 2 hours back - 4 hours. And you live somewhere it's dark 24/7 - totally unreal, but let's just go with it. 4 hours * 365 day = ~1500 hours a year. Someone sell you a LED and claims of 30,000 hours. It should last you 20 years if you lived on te dark side of the moon, in total darkness

              That's not happening at all with LED bulbs, headlights, under counter strips, fluorescent bulb replacements. They are dimming and changing color.

              If you want to really geek out on LED stuff, you should read http://www.candlepowerforums.com - some good info there.
              Originally posted by Matt-B
              hey does anyone know anyone who gets upset and makes electronics?

              Comment


                #8
                It's to the point that even cree is failing at some of their products.
                I wouldn't cite Cree as a quality source at this point. Their LED business is dying, and they've purchased low quality Hong Kong based LED manufacturers, and stuck their Cree name on those products.

                Cree's LED business is an after thought next to their Silicon Carbide business, which is nicely protected as an essential industry by the department of defense.

                That's not happening at all with LED bulbs, headlights, under counter strips, fluorescent bulb replacements. They are dimming and changing color.
                Not really the LED's fault in that area. The LM80 ratings are typically based on sub 70C operating temperatures. Fixture manufacturers are doing a poor job in the thermal department, or doing stupid things like placing rubber bands in the packaging. Synthetic rubber eats away at the phosphors in the LEDs.

                If you're buying residential bulbs, at least stick with Title 24 and Energy Star rated fixtures. They go through actual finished goods accelerated life testing. The fixture manufacturers that release a lot of Title 24 compliant or 10 year rated commercial fixtures, use Citizen (Eaton) or Nichia (Acuity) as their LED sources by the way.

                Comment


                  #9
                  Yea, but still.
                  Originally posted by Matt-B
                  hey does anyone know anyone who gets upset and makes electronics?

                  Comment


                    #10
                    Originally posted by earthwormjim View Post
                    Resistors are a poor solution. You're just wasting energy. LED bulbs have a nice benefit, I've accidentally left my lights on over night, and had no issue starting the car in the morning the next day. If you stick resistors in to fix the check panel, you don't get this power savings.

                    The real fix, as shown in AndrewBird's link, is to rewind the reed relays. Ignore the red wire jumper, that shouldn't be added.



                    I did this on my touring. The brake coils, A, needed about 150 turns each, for my 5W LED bulbs to not trigger check errors. Stock was around 20 turns. I used 26 AWG magnetic wire.

                    I did not have to touch the other relays, as long as my lights are not on while starting the car, I don't get a check indicator.
                    Did you just pull the reed off and add more coil layers? Sound like they would be pretty thick with about 7 layers.

                    I have a spare check relay and was planning on just jumpering it since Im not terribly worried about a bulb outage.

                    I wonder if I could just use some 4 plug relays instead. Pin 30 would be the line in from battery (or existing line in from lamp circuit/check relay). Pin 87 would be output to check panel. Pin 86 existing input to check relay. 85 is grounded. Wouldn't that enable the check control to work while negating the need to mess with reed switches?
                    Last edited by PDXPeter; 05-21-2018, 09:27 AM.

                    Comment


                      #11
                      Originally posted by PDXPeter View Post
                      Did you just pull the reed off and add more coil layers? Sound like they would be pretty thick with about 7 layers.

                      I have a spare check relay and was planning on just jumpering it since Im not terribly worried about a bulb outage.

                      I wonder if I could just use some 4 plug relays instead. Pin 30 would be the line in from battery (or existing line in from lamp circuit/check relay). Pin 87 would be output to check panel. Pin 86 existing input to check relay. 85 is grounded. Wouldn't that enable the check control to work while negating the need to mess with reed switches?

                      I de-soldered the reed switch and the coils around it. Slid the coils off of the switch, and using my transformer winder at work, wound 150 turns around a small screw driver shaft. A drill would work fine too, just keep track of your turns.

                      I still have the old coils, so it's completely reversible if you change your mind.

                      150 turns wasn't very cramped, I dropped the wire gauge thickness from 19 to 26 awg. 26 AWG is half the diameter, so even taking up the same width I got about double the number of turns per layer, and each layer was half as thick as the old layers.

                      Height wise, you're limited by the case, and it's designed to accommodate relay set B, which are significantly taller than the brake light relays. There's plenty of room.

                      To figure out the number of turns, i measured the threshold current with the old relay coil, which had around 20 turns. It took ~1.5 amps to trip, which yields a sensitivity of 30 ampere-turns. The LED lights draw about 375 mA for the red brake light colored ones. So to match the sensitivity, I needed at least 80 turns.

                      I chose 100, to give some margin, however, I found I still would get the brake check light after repeated use. Looking at current draw on a scope, the LED lights actually draw about 250 mA for about 100ms or so, then start drawing full power after. So I really needed the turns to account for this lower initial draw, hence ultimately using 150 turns.

                      Lastly, I verified if the check control still functioned, which it did if I disconnected a bulb. I'm hopeful it trips too if I start losing LED dies.

                      There's any number of alternatives to this approach. I was seriously considering using opto-couplers, but ultimately decided to just rewind the reed relays because I have access to every conceivable gauge of magnetic wire, and a nice transformer winder, so why not?
                      Last edited by earthwormjim; 05-21-2018, 06:13 PM.

                      Comment


                        #12
                        Originally posted by earthwormjim View Post
                        Resistors are a poor solution. You're just wasting energy. LED bulbs have a nice benefit, I've accidentally left my lights on over night, and had no issue starting the car in the morning the next day. If you stick resistors in to fix the check panel, you don't get this power savings.

                        The real fix, as shown in AndrewBird's link, is to rewind the reed relays. Ignore the red wire jumper, that shouldn't be added.



                        I did this on my touring. The brake coils, A, needed about 150 turns each, for my 5W LED bulbs to not trigger check errors. Stock was around 20 turns. I used 26 AWG magnetic wire.

                        I did not have to touch the other relays, as long as my lights are not on while starting the car, I don't get a check indicator.
                        Hi Earthworm,

                        How did you get to 150 turns for each switch? I'm at 70 turns right now and the coil is a little more than 2x the length of the original coil.

                        Thanks,
                        John

                        Comment


                          #13
                          Scratch that, it seems like you layered the coils, correct? 3 layers of 50 coils?

                          Comment


                            #14
                            Still not working unfortunately. Lights are coming on

                            Comment


                              #15
                              Originally posted by jjc034 View Post
                              Still not working unfortunately. Lights are coming on
                              You can include some bleeder resistors to add to the current draw if you don't want to add more turns than you already have. Just wire one end of the resistor to the same side of the coil as the lights hook up to, and the other end of the resistor to ground. Something around 100 ohms should be sufficient.

                              I ended up having to add these resistors, because at colder temperatures, the LEDs draw less current since their forward voltage is higher.

                              Comment

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