Jaydub Posted March 15, 2012 Share Posted March 15, 2012 Watched the missus drive off into the fog on her way to work the other morning and was surprised how quickly the rear lights disappeared into the murk. Decided to do something about it and ordered some L E D bulbs, once fitted they were no better than standard on tail and worse than standard on brake. Have changed back to standard for now but wondered if we need to do anything more involved to fit L E D s to our cars.I know that resisitors are needed in the indicators but that is (I believe) to draw enough current to heat the relay, surely there is nothing similar in the tail and brake circuits. I did read somewhere that you can't run L E D s and standard bulbs in the same circuit (it has a standard no. plate lamp) but can't understand why that would be the case... anyone?Sorry if this has been covered before.P.S. Her car is a Spitty powered '67 13/60 with an alternator conversion and H4s up front. Link to comment Share on other sites More sharing options...
mazfg Posted March 15, 2012 Share Posted March 15, 2012 LED's should be a straightforward swap for incandescent but some cars have a bulb fail warnig in the lighting circuit, so a load resistor may have to be fitted across any LED's that cause this warning. LED light is directional though and often brightnest when looking straight on and not so viewed from the side (unlike incandescent). There are a lot of LED replacements out there....not all of the best quality. Various types of clusters to large single type LEDs, they can also vary in brightness. As for the indicators, there are now straightforward replecement flasher relays out there now that accomodate LED indicators without the need for the added resistor. Link to comment Share on other sites More sharing options...
esxefi Posted March 15, 2012 Share Posted March 15, 2012 do the led's appear brighter if wired direct to a 12v source?if so make sure they are wired in parallel and not in series ie,each bulb needs its own supply and earth,if not a normal bulb will sap the power in much the same way christmas tree lights work. :) Link to comment Share on other sites More sharing options...
Jaydub Posted March 15, 2012 Author Share Posted March 15, 2012 Thanks for that both. No warning lights in a Herald!! After trying them on the other half's car I tried them in my hot rod with the same result, then in one of our Harleys where the fitment is sideways on - they really are rubbish in that application, as stated you do need them to be seen end on.The parallel wiring point makes sense (tho' I didn't realise drag strips were wired that way) - maybe I'll have another play at the weekend if I've finished rebuilding my dynamo, from all I've read it should be a worthwhile upgrade... Interest's sake I'm using 24 L E D s, I'll let you know the results in case any one is interested. Link to comment Share on other sites More sharing options...
Howard Posted March 15, 2012 Share Posted March 15, 2012 Each bulb has a built in resistor to allow it to operate at 12v since the LED itself will only operate at few volts and a draw a few milliamps current. If you wire an LED bulb in series with an ordinary bulb, the LED should light up BUT the ordinary bulb will not illuminate (or glow very very dimly).On my car I have LED running lights in parallel with the standard side lights to improve visibility and they work very well as you can see:- Link to comment Share on other sites More sharing options...
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