[DML] Re: Fan Zilla vs. BA7 LED "Fan Fail Light"

["Matt" <supermatty@xxxxxxx>]

When I installed LEDs for turn signals in my 1998 Malibu, it would 
cause them to flash very fast as a warning that I had a bulb out.  
The problem was that they weren't drawing enough current to make the 
module think I had a working bulb.  The easy fix for is kind of 
stupid, and defeats the purpose of having LEDs in the first place.  

I'll put up some calculations here with examples so it makes it easy 
for you to see how to calculate this on your own.

What is the wattage of the original BA7 bulb?  I have no idea so 
let's just say 5W.  So:

I = 5W/12V = 417 mA

How much current does the LED draw?  Let's just say it's 50 mA.  

417 mA - 50 mA = 367 mA

So, I'm willing to bet if you make your LED circuit draw an 
additional 367 mA or so, it will work.  How can we do this:

R = 12V/367mA = 32 Ohms

So find a resistor that is approximately 32 Ohms and can dissipate 
about (12V*12V)/32ohms = 4.5W.  Put this in parallel with your LED.  

If you find the exact power requirements of the BA7 bulb, then you 
can redo the calculations above to find out what you need.

Hope this helps.

Matt
#1604


--- In dmcnews@xxxxxxxxxxxxxxx, "ryanpwright" <yahoo1@xxxx> wrote:
> How would one go about making an LED appear to be a normal bulb, so
> that a BA7s LED could be used in place of the fan fail bulb and not
> cause problems with the SpecialTAuto 2x2? An inline resistor, 
perhaps? 
> 
> -Ryan





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