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Jesse Chen
Starting Member
11 Posts |
 Posted - 06/08/2012 : 04:01:52 AM
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Hello all,
I heard that you need resistor for led bulb turn signals so it won't hyper flash. So i was wondering if you also need resistor for led brake bulbs? would you need resistor on led brake light?
Thanks a lot,
Jesse
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Edited by - Jesse Chen on 06/08/2012 04:02:16 AM |
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Geo
Advanced Member
Canada
495 Posts |
Posted - 06/08/2012 : 04:48:00 AM
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| LED is a current driven device. It always needs a resistor in series or some other current limiting device. If you are replacing an original LED in a car I would suggest you use a proper replacement. If you are trying to replace an existing incandescent bulb with LEDs, you definitely need a resistor. But you can buy many LED assemblies and indicator lights with resistors already built in. |
GJN |
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oberkc
Advanced Member
USA
1744 Posts |
Posted - 06/08/2012 : 10:58:39 AM
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I replaced my formerly-incandescent turn signal and brake lamps with LED. This necessitated replacing the flasher unit to an electronic variety, readily available at my local car parts store. Replacement units were off-the-shelf lamp assemblies, remove-and-replace. This was not a science project.
No extra (beyond anything that was built in as part of the replacement lamp unit) resistors or other electronics needed. Nothing needed for brake lights. Simple. |
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BLH
Advanced Member
3795 Posts |
Posted - 06/08/2012 : 1:12:48 PM
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| The replacement LED bulbs should have the necessary resistors in it for 12 volt operation. I have seen resistors being added across the lights to ground for more current draw for the flashers, but as mentioned they make electronic flashers so added resisters would not be needed. |
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oberkc
Advanced Member
USA
1744 Posts |
Posted - 06/08/2012 : 7:11:11 PM
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quote:
I have seen resistors being added across the lights to ground for more current draw for the flashers
I assume that adding resistors would REDUCE the current draw. |
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BLH
Advanced Member
3795 Posts |
Posted - 06/09/2012 : 08:55:26 AM
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In series with the +12 volt or ground lead would reduce the current.
Connected across the bulb so one lead is fed +12 volts through the flasher and the other one is on ground would increase the total current being drawn.
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Geo
Advanced Member
Canada
495 Posts |
Posted - 06/09/2012 : 1:23:29 PM
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LEDs will draw less current - the problem is that this will screw up the car diagnostics. They will indicate defective bulb. One method is to put in parallel resistors to increase the current sufficiently for the diagnostics to be happy again. This partly defeats the purpose of the modification, as the current draw will be about the same as before and there will be no energy saving. There is an article in the May issue of Elektor magazine how to build a "lossless load" - a circuit which fools the diagnostics into thinking the current draw is that of an incandescent while maintaining the low LED draw.
It's interesting, but a bit of an overkill. It costs more that the bulbs for the life of the car and I'm not sure energy saving is really that much of concern. |
GJN |
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Geo
Advanced Member
Canada
495 Posts |
Posted - 06/09/2012 : 3:03:37 PM
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| BTW, why do people replace incandescents with LEDs in their cars? I just never thought about it - actually, never had a reason to think about it. Never had a burned-out lamp. Is it the life of the LED? |
GJN |
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oberkc
Advanced Member
USA
1744 Posts |
Posted - 06/09/2012 : 3:33:09 PM
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I have several failed signal, brake, and indicator lamps over the years.
I replace them for a couple of reasons...I like to keep my little honda insight hybrid current with technology. Second, I like the quicker on-andoff response on the signals. Third, I like not having to replace bulbs. Not a big deal either way.
I must not have anything better to do. |
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Geo
Advanced Member
Canada
495 Posts |
Posted - 06/10/2012 : 05:32:15 AM
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| Good enough reasons. I used to fix my cars but stopped doing it with the arrival of electronic control. Now I don't even remember when I opened the hood the last time. But I did check this morning and it seems I have LEDs. But can't figure out how to even replace the light if for some reason I had to. Looks like I'd have to buy a new car ;-)) |
GJN |
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Topic |
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Do you need resistor for led bulb for tail lights?
