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  Connecting LED Strip Lamp Assemblies

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Author Topic:   Connecting LED Strip Lamp Assemblies
cohasett73 posted 04-27-2010 09:22 PM ET (US)   Profile for cohasett73   Send Email to cohasett73  
I have spent several hours, to no avail [trying to connect together some LED strip lamp assemblies], first them in series and then in parallel. Power to buss [sic] bar is good, fuse is good, and switch continuity is good. The continuity to the LED lamps is good. Am I stupid? I know LED's are [polarity] sensitive, so what the hell am I doing wrong? By the way the battery is full charged too. I am trying to iluminate my Cohasset for night fishing.

Mr. Hebert, HELP! Thanks,
Tom from Rubicon,WI

Chuck Tribolet posted 04-27-2010 10:47 PM ET (US)     Profile for Chuck Tribolet  Send Email to Chuck Tribolet     
Are these individual LED's or some prepackaged unit?

If the former, you need current limiting, either with a
resistor or a chip that's made for the job. If you hooked
up a naked LED to the boat battery, you blew the LED. Measure
the resistance of the LED. It should show low resistance
one way and high resistance the other.

If it's the latter, measure whether you have voltage where
you attach it.


Chuck

cohasett73 posted 04-28-2010 07:10 AM ET (US)     Profile for cohasett73  Send Email to cohasett73     
Chuck--The lamps in question are LED utility light strips from West Marine. Before I started drilling holes, I took one out of the packaging and touched the conducters to the battery poles. That one tested perfectly.

Tom from Rubicon,WI

Chuck Tribolet posted 04-28-2010 11:46 AM ET (US)     Profile for Chuck Tribolet  Send Email to Chuck Tribolet     
Test the strip again. If bad now, replace.

Work back towards the battery from where the lights are
installed looking for voltage.


Chuck

davej14 posted 04-28-2010 07:06 PM ET (US)     Profile for davej14  Send Email to davej14     
If the strips are not polarity protected then you could have also destroyed the led chips by hooking them up with reverse polarity. You would have to check your installation instructions for a warning about this possibility. If the strips are designed for a 12V system then they should already have a current limiting feature built in and you would not damage them if the polarity were correct.

In the old days a current limiting resistor was used. The correct way to make a quality fixture today with high intensity LEDs is to incorporate a buck or boost converter with feed back for temperature to regulate current at the optimum level. I suspect many of the marine strips still use a plain old resistor because it is cheap.

jimh posted 04-28-2010 08:43 PM ET (US)     Profile for jimh  Send Email to jimh     
A light-emitting diode is a diode. If a diode is connect with a voltage source so that the diode is reversed biased, no current flows, unless the reverse voltage exceeds the rating of the diode's maximum reverse voltage. If the diode's maximum reverse voltage rating is exceeded, the diode may break down.

Check the specifications of the LED's to see if the maximum reverse voltage rating is greater than 14-volts (or about the maximum voltage from a battery). If the LED maximum reverse voltage rating is more than 14-volts, then the LED could not be damaged by connecting it to a 12-volt battery with the polarity reversed.

If the LED does not have a current limiting device provided, if connected directly to a 12-volt battery the forward current will be very high and the LED will burn out in a matter of a few milliseconds. In this case it would be more damaging to connect the LED to the battery with the proper polarity than with the reverse polarity.

Chuck Tribolet posted 04-29-2010 12:25 AM ET (US)     Profile for Chuck Tribolet  Send Email to Chuck Tribolet     
What JimH said: reverse polarity doesn't blow LEDs.
It might blow a current limiting chip.

I stand by:

Test the strip again. If bad now, replace.

Work back towards the battery from where the lights are
installed looking for voltage.


Chuck

cohasett73 posted 04-29-2010 08:27 AM ET (US)     Profile for cohasett73  Send Email to cohasett73     
Thanks for the replies Chuck,Davej14, and jimh.

One thing is for sure, these light strips don't work wired in series. As for wiring in parallel, that works.But, and this is a big but. I was in a bit of a rush completeing the parallel circuit. Having tested the fuse for continuity
I then went on to the next thing. When tested,no worky.

Returning to the project the next mourning I noticed the fuse and cap on the console. WTF!!! I installed the fuse pulled the switch and Holy Clark Griswold, all the strips were glowing red.
I checked again after dark. The whole inside of the Cohasset is bathed in red. Sorry no pics,cheapy camera doesn't have a flash disconnect.
Moral of this thread...Don't start drinking beer until all your work is complete and tested.
Tom from Rubicon,WI

stevesalick posted 04-29-2010 01:40 PM ET (US)     Profile for stevesalick  Send Email to stevesalick     
Tom, especially that fine import beer you're known to drink. Maybe you should find a photographer, take him fishing some night, get some fish and photos in one fell swoop! yer buddy Steve - Salick Photography, Inc.
jimh posted 04-29-2010 01:53 PM ET (US)     Profile for jimh  Send Email to jimh     
ROGER on the installation of new LED lighting in the cockpit being somewhere between a maximum of a 1-BEER to 2-BEER job.
cohasett73 posted 04-30-2010 07:32 AM ET (US)     Profile for cohasett73  Send Email to cohasett73     
I'll have to take you up on the night fishing trip Steve.
Actually it was Blatz Lite what got my wires crossed.
Bottom line; I am very satisfied with these LED strips.
Early mourning or night fishing in my CohassetII just got
alot safer. Lake Michigan here I come.
Tom from Rubicon,WI
davej14 posted 05-02-2010 01:51 PM ET (US)     Profile for davej14  Send Email to davej14     
Be sure to leave the Blatz Lite on shore during those night fishing trips !

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