Multiple LED's, Series or Parallel?
Printed From: the12volt.com
Forum Name: Car Security and Convenience
Forum Discription: Car Alarms, Keyless Entries, Remote Starters, Immobilizer Bypasses, Sensors, Door Locks, Window Modules, Heated Mirrors, Heated Seats, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=25295
Printed Date: September 18, 2025 at 9:24 AM
Topic: Multiple LED's, Series or Parallel?
Posted By: yoda888
Subject: Multiple LED's, Series or Parallel?
Date Posted: January 26, 2004 at 12:35 PM
Hi All, I finally got the old DerringerII alarm out of the car! I hooked-up the Crimestopper alarm. So far it seems to be working pretty good. Anyhow, I got a LED question. What is the recommended way to hook up LEDs? In series or in parrallel? A couple of things to consider. -original alarm LED voltage output was 2volts
-original alarm had 3 LEDs
-new Crimestopper voltage output is now 3volts
-i'd like to hook up all 3 LEDS to the new alarm Advice? comments? tips? Thanks!
PS: are LED's "directional" in current? As in, can I screw it up by hooking up neg terminal to the pos terminal on the LED? Or will it simply not "work" unless I hook up the terminals correctly?
Replies:
Posted By: bmf1000d
Date Posted: January 26, 2004 at 12:49 PM
Yes there is the longer shaft of the diode is the postive or the most and standard is the side lead on flat
side of bulb is negative.
-------------
"Big" Mike
Double Take
Fremont, Ne
remember to check all your wires with a dmm not a test light!!
i take no responsibilty whatsoever for the vailidty of the info nor consequences thereof
Posted By: Teken
Date Posted: January 26, 2004 at 4:43 PM
Something to consider, if you wire the LED's in series. If any of the LED's should fail. All of them will not function.
If you wire the LED's in parallel, if one or more fail. The others will continue to work.
Some alarms, require that the LED's be active, so if the LED's should not function anymore. Either the alarm will not perform normally, or it may function erracticly.
You may hook up all three of the LED's directly without any resitors if you wish.
If the leads to the LED are no longer different in length. Simply look into the LED, the thinner side of the LED is the positive (anode) and the larger pin is the negative (cathode)
If you have a DMM with a diode check, you can varify that fact, as well the LED will light up to confirm the proper polarity.
Regards
EVIL Teken . . .
Posted By: yoda888
Date Posted: January 26, 2004 at 5:26 PM
Evil Teken,
I talked to tech-support over at Crimestopper. They said that I should wire the LEDs in series. Apparenlty if I run it in parrallel, it would fry the LED output on the alarm brain. The guy said 2 LEDs max in parallel. So now I'm thinking. Can't I wire 2 LEDs in parallel? And then wire the whole circuit as a series? (or wire 2 LEDS in series with 1 LED parallel to that circuit?) Am I talking out of my arse here?! 
Posted By: bmf1000d
Date Posted: January 26, 2004 at 5:56 PM
why not get a tri color led and wire that in
-------------
"Big" Mike
Double Take
Fremont, Ne
remember to check all your wires with a dmm not a test light!!
i take no responsibilty whatsoever for the vailidty of the info nor consequences thereof
Posted By: xetmes
Date Posted: January 26, 2004 at 7:04 PM
or use a transistor to handle all the current you want. then you can hook a million up...
Posted By: Teken
Date Posted: January 26, 2004 at 7:05 PM
Yes, you can do what you suggest.
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