Led bulbs don't work

[Madwand]

Any idea why these won't work and their incandescent counterparts work fine?

[captainjay]

Polarity, you will find a lot of 12 volt light fixtures where wired without one thought to polarity. LED won't work if the polarity is wrong. Anchor lights are almost always wrong because they are the hardest to fix. :-)

[Reefmagnet]

^^^ x1. I'd vote the good captain is on the money

[woodyapex]

I bought lots of Crees off eBay . Some single terminal and some double to suit light fittings .
Not sure why but I found them hit and miss . Gave the job of changing them to our lass and viola the job was done .
I think polarity is definitely an issue and I think if you get it wrong the first time potentially the bulbs can blow too . Mine were very cheap so I'd no need to worry .

[K_V_B]

The second one is a 120V one, I would not expect that to work on 12V...

[Sternwake]

Yep, likely a polarity issue. With an 1156 type of bulb, you will have to swap wires to the bulb receptacle, but you can test the bulb by putting 12v+ on the bottom contact and - on the bulb base.

Note that LEDs with 5050 SMDs are now outdated. Some chipsets like 5730s are more lumens per watt and more lumens per chip, and they can fit more chips on each bulb for significantly more light.

I recently acquired some t10 wedge base LEDS with 5730's that finally meet my expectations as to color and output, after much searching and money wasted since 2007. These were 10 for 6$.

I have 20 and no failures yet. Can't say the same about 5050's driven hard for less overall light

[nigelmercier]

Originally Posted by Sternwake

Note that LEDs with 5050 SMDs are now outdated...

Of course they are, I've just switched to them

More info on 5730 here

[SURV69]

Almost every LED bulb I have, have no polarity issue ... positive/negative does not matter. EVERY LED bulb, I've bought in the past year seems to have no polarity.

But, I have a hunch that for a number of reasons, polarity does matter in automotive receptacles.

[jongleur]

I just bought some LEDs and they
had reversed polarity. Easy enough
to switch the wires in the fixture.

[TurninTurtle]

Automotive LEDs do care about polarity.

Actually any LED requires the correct polarity DC to function.

The ones that work either way (or on AC) have to have a diode "bridge" or full wave rectifier to "adjust" the polarity. There's not much point in putting that extra cost into the automotive which are typically "keyed" to only plug in the right way.

[tkeithlu]

But 12v DC medium screw base (as in 120v AC lamp) LEDs are readily available. I use them in all the work lights on the boat. Just remember to mark them with a Sharpie so you won't mess up and put one in a 120v socket.

[Madwand]

So polarity is an issue and it's not an issue. Good to know.

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[Lake-Effect]

Originally Posted by Madwand

So polarity is an issue and it's not an issue. Good to know.

LEDs as raw components care about polarity. Commercial LED incandescent bulb replacements may or may not care, depending on how they were designed. Better?

If the polarity requirement isn't described in the LED bulb's specs, you can simply try them using 12v on 2 wires (from a fuse- or breaker-protected circuit please!) and touch to the bulb terminals. If the bulb only works one way, it's polarity-sensitive.

[nigelmercier]

... and if it goes BANG it needed a current limiter.

[Madwand]

Already returned them and given up. One of them was a 110-volt bulb, same thing applies?

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