Changing LED in door handle light

Thread Starter

shezza

Joined Mar 19, 2014
66
I have a 2012 Audi C7 with puddle lamps in my door handles. One of them was not working, so I decided to open up and investigate. I found that it was water damaged.
I want to upgrade them anyway, due to them not being very bright. After the resistors, there is 3.23V being supplied. How close does the forward voltage of the LED I am
buying have to be to that number? Also, any tips as to where I can find the brightest 2835 chip? Due to space, it is difficult to fit anything larger. Width-wise, there are too many things in the way. Height-wise, there is a projector in the way. I guess I could give it up if the brightness of the chip made up for the lack of it. Though It seems width is more necessary when going up in lumens, than height...
 

MisterBill2

Joined Jan 23, 2018
8,995
Really, you need to know the voltage being supplied before the current limiting resistors, because a replacement LED will probably require both a different voltage and a different current. You will need to know the design current rating of whatever LEDs you get for replacements. So you will need to buy them from a reputable source, not Amazon .
 

Thread Starter

shezza

Joined Mar 19, 2014
66
Really, you need to know the voltage being supplied before the current limiting resistors, because a replacement LED will probably require both a different voltage and a different current. You will need to know the design current rating of whatever LEDs you get for replacements. So you will need to buy them from a reputable source, not Amazon .
I have bought enough eBay crap to know you get what you pay for with LEDs. Even though LEDs are supposed to last a lot longer than older lighting tech, due to all the low-quality junk around, the average LED does not last as long as an incandescent globe. It is a real crying shame! I bought some Cree XML2s from Element14.
I have checked the voltage past the resistors though and it is within the requirements of the LED. I have used an LED driver before, I understand that is how you get the most out of your high-powered LEDs, though how do I measure the current that will be drawn from my car, short of connecting it all up and measuring the current?
Is my worst case, just not taking full advantage of the LEDs full power?
 

MisterBill2

Joined Jan 23, 2018
8,995
My statement was a request to check te voltage supplied to the dropping resistors, NOT to the LEDs. The reason is that it is important to know how much voltage must be dropped across those resistors at the current that the LEDs should be operated. It might be the battery voltage, or it might be some lower value.
To determine the current that the present LEDs draw, you can measure the voltage at each end of the resistor, relative to the common negative, and then, with the power off,measure the value of that resistor. With that information it is simple to calculate the current.
 
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