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Alternator annunciator light...how to wire??

B

benbell4140

Well Known Member
Does anyone know what components i will need to purchase so I can make a light come on with an alternator failure? I know that vans sells a kit but i dont want to use the square light that they supply. I'd like to use a regular round LED. If I cant figure it out I'll just wire it up so that the light stays lit up while the alternator is charging and turns off upon a failure.

Thanks
 
what engine monitoring system do you have? :) That light may not be necessary if you have any of the modern EMS systems (Dynon, GRT, AFS, etc..)
 
I just have standard analog instruments. The alternanator is the "kit" from vans, not sure if it's plane power or what.

Thanks
 
Assumming you have a 3 prong plug, In all likelyhood you have all the electonics already. The "L" terminal is the idiot light function. It supplies ground in a failure.
Take any 12v light you want, put one wire 12v to a buss thats on when the master is on, put the other wire to the "L" terminal and you will have an idiot light on the panel. Will be both an alt failure light and a "you left the master on you idiot" light.
Someone back me up on the terminal im going off the top of my head.

ed. OK I found my drawing Grab drawing 13, click the little arrow to load it and see if that alternator drawing helps you
 
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On some alternators, I believe it's "I" for Indicator.

Nope! You're right, it's "L" on mine.
 
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Just be careful not to connect the LED directly to your 12V source unless it is designed for that purpose (like the ones TX7A has given the website for). Most LEDs will require a current limiting resistor in series with the LED and the voltage source. The value of the resistor will depend on voltage and nominal LED current. Failure to install a resistor will most likely burn out the LED very quickly. To calculate the required resistance:voltage(V)/current(A)= resistance(ohms). Example: 12Volt / 0.020 Amperes (20 mA) = 600 ohms
 
BillC said:
Just be careful not to connect the LED directly to your 12V source unless it is designed for that purpose (like the ones TX7A has given the website for). Most LEDs will require a current limiting resistor in series with the LED and the voltage source. The value of the resistor will depend on voltage and nominal LED current. Failure to install a resistor will most likely burn out the LED very quickly. To calculate the required resistance:voltage(V)/current(A)= resistance(ohms). Example: 12Volt / 0.020 Amperes (20 mA) = 600 ohms
Click to expand...

Resistor is built into the light. "+" terminal is also labeled
http://www.mpja.com/prodinfo.asp?number=16961+LE
 
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You can also very cheaply (maybe $8 in parts) build a voltage monitor circuit that you can adjust to turn on an LED at whatever voltage you want.
 
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