The only thing you have to watch out with LED's is to limit their current.
This is done by adding a resistor in series with the LED.
Most LED's should be limited to 20mA forward current so based on a "nominal"
13 volt electrical operating voltage the resistor required would be
V=IR ..... R=V/I ...... R = 13/.02 .....
R = 650
Going to the next highest available general series resistor you end up
putting in a 680 ohm. Even if the voltage reached 15 volts (bye bye
electrical system) the LED would still only have a forward current of 22mA.
The disadvantage with using an LED here is that LED's wash out in strong
sunlight so I would look for so called Super Bright LEDs if you want to use
them. You can steal them out of the high stop lights of many modern vehicles
:-)
Oh, it helps to get the LED the right way round as well otherwise you end up
with a DED - a Dark Emitting Diode.
Tony
-----Original Message-----
From: Martin J.Tuck <102034.2747@compuserve.com>
Date: Thursday, February 04, 1999 2:13 PM
Subject: Re: Charge Indicating Lamp
>Re: Charge Indicating Lamp
>
>I'm still thinking of installing a charge indicating lamp but want to know
>if a 12V LED will be OK.
>
>The manual calls for a 3W/12V lamp but this is also called for the optional
>alternator charging lamp so maybe thats why it says 3W (3 watts
>presumably).
>
>I have a 12V LED for my starter engaged lamp and it works just fine but
>electronics is my weakness (well, one of them). Is a large current running
>through the lamp if the recifier is not charging and can an LED 'burn out'
>as a result?
>
>The 12V LED I use is about 0.4 inch diameter so seems pretty 'meaty' by LED
>standards but is not rated with any sort of wattage.
>
>Grateful for any help or pointers.
>
>Regards
>
>Martin Tuck
>N152MT
>Wichita, Kansas
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