6 volt LED in a 6 volt Buick HELP!

I have attempted to use 6 volt LED lights in my parking/brake lights, but they do not light. I have purchased LED's from two different vendors. Neither will light with my parking lights on. Any suggestions? The vendors have said they should work. Does it have anything to do with the grounding in my car? Not sure if I have a positive or negative ground. My regular bulbs work fine. I am waiting for the turn signal lights, but expect the same. Any ideas??? Thank you.

I'm not very knowledgeable about auto electrics, but do know Lucas electrics but that is for another time. Anyway, I know that LED's use only a fraction of the current that regular incandescent bulbs use. Lot of times the LED's don't pull enough current to activate the turn signal flasher and it has to be replaced with one made especially for LED's. Someone will come on here and explain why your LED's aren't working and what may be done to get them to work.

Not sure what Polarity you have . It I easy to check. Follow the cars groud strap normally connected to the engine block and see which battery post it goes to. That is your ground polarity . LED bulbs are polarity sensitive. They need negative ground. The brass base is negative. The contact gets positive when lit.

In other words LED bulbs won't in a positive ground system.

Not unless they are specifically configured for positive ground (in which case the won't work in a negative ground car). I don't know if you can actually buy an LED bulb replacement configured for positive ground, but theoretically, one could be made. I suspect this is a niche market that's too small for a supplier to address.

According to the dealer I purchased the

polarity insensitive bulb so it wouldn't be a polarity issue.

Connect a jumper wire to each terminal of your battery. Be careful to be sure that they do not touch each other. Hold the jumper end connected to the negative post of the battery to the base of the bulb. Touch the other jumper end to the contact on the bottom. The LED bulb replacement should light. If not, reverse the leads. If it still does not work, you have a defective LED or possibly one made for 12 volts DC.

Joe, BCA 33493

+1 on what Joe said. As mentioned above there are replacement LED bulbs that are polarity insensitive, they will work on both ground systems. Now another thing is that LEDs are more critical of low voltage. If the voltage at the bulb socket is to low the LED will not light. Leds are pretty much either on or off, they don't dim much with low voltage, they just go off, where an incadesent bulb will get dimmer with low voltage. First thing to check is like Joe said... Carefully connect the LED to the battery and see if it lights. Also, your Buick is 6 volt negative ground if it is stock. Good luck.

Robin

All Buicks are negative ground

+1 on what Joe said. As mentioned above there are replacement LED bulbs that are polarity insensitive, they will work on both ground systems. Now another thing is that LEDs are more critical of low voltage. If the voltage at the bulb socket is to low the LED will not light. Leds are pretty much either on or off, they don't dim much with low voltage, they just go off, where an incadesent bulb will get dimmer with low voltage. First thing to check is like Joe said... Carefully connect the LED to the battery and see if it lights. Also, your Buick is 6 volt negative ground if it is stock. Good luck.

Robin

How can a LED be polarity insensitive? LED is Light Emitting Diode and only let current through one way? also if they are wired in series then depending on how many there is a 6 volt battery might not have enough energy to activate them.

also if they are wired in series then depending on how many there is a 6 volt battery might not have enough energy to activate them.

But they aren't wired in series. The bulbs in the car are wired in parallel. The individual LEDs on the replacement lamp are wired as necessary to work with 6V, as they are 6V-rated LED replacement lamps. I'm curious about the polarity-insensitive thing, however. I do know that it's pretty easy these days to build voltage-sensing and switching circuits into devices. My computer charger works on both 110V and 220V, for example, and Miller sells welders that will automatically set themselves for input voltage. I can envision a sensing and switching circuit built into the base of the lamp, but it would seem like a lot of work.

When you add the turn signals you will likely have to add a ballast resistor to the circuit to have it pull more current, otherwise the flasher will blink so as to have an extremely short "on", and relatively longer "off". I had this on a 12-Volt car. Another later solution was to switch to an electronic mechanical flasher unit which works perfectly. I don't know if one of these is available for 6-Volt applications - perhaps someone more learned can offer an opinion or an example. The LED is dramatically brighter on several of my cars which are converted, and also light-up to full intensity more quickly, so I would have to believe that this could provide added safety in traffic.

To explain the polarity insensitive statement... LEDs by themselves are polarity sensitive. However, when they are built into an assembly (replacement bulb) the electronics inside can be configured to make them insensitive to polarity. If you have an electronics background think of a bridge rectifier in front of the LED array. In this configuration any polarity INCLUDING AC will light the LEDs as long as the voltage is correct for the design.

Now another thing to keep in mind is the statement about LEDs using MUCH less current than regular bulbs. This is true and can/will cause other problems. Starting with turn signals, as was mentioned above you will need either a flasher designed for LEDs or as Marty said you will need a ballast resistor to provide enough current load for the regular flasher to work. If there is to little current the signals will just light up and not flash... *** I just reread Martys post above and will defer to his experience as to how the light might respond. My experience is that the light just stays on, however depending on the circuit other actions are possible. *** This is common and flashers and resistors are available to fix the problem. Another thing that can happen with LED replacement bulbs is the low current can cause the lights to operate intermittantly if there is a switch, connection, splice etc that is questionable. The current from the regular bulbs will actually cause a small arc in the connection or switch and cause a cleaning action where the LED current is so low this will not happen and the circuit will be open and no current will flow and therefore no light from the LED. This is uncommon but worth mentioning.

Another thing worth mentioning has to do with the polarity insensitive LED bulbs... by the nature of how they are made they WILL be more sensitive to low voltage than the fixed polarity models. By design there will be a loss of approximately 1.2 volts in the bulb design. While this is not a problem as the bulob is designed around this voltage loss it does mean that the 6 volt car now really only has 4.8 volts inside the bulb... Soooo if the car is running a little low. or the wiring is a little lossy the bulbs might not light.

Just a few things to think about. I hope this helps.

Robin

Robin:

I think that the bridge rectifier ahead of the LED array does provide an easy way to make the bulb polarity insensitive.

Since these use so little current, I have noticed that they will give some light in a circuit where a supply switch is slightly leaky. I have a LED nightlight on a wall switch in a bedroom. The LED nightlight will give a dim light with the switch in the off position and full light with the switch in the on position. If I unplug the nightlight, then the bulb goes completely dark. In experimenting with LEDs I have found that the brilliance does vary with the applied voltage although not as linearly as with an incandescent bulb.

Joe, BCA 33493