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 > LED light and 12v Voltage? UPDATE-OOPS!/Got Kohrees too.

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BFL13

Victoria, BC

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Posted: 11/12/20 07:46pm Link  |  Quote  |  Print  |  Notify Moderator

Update 15 Nov---the lamp was ok, it was a loose wire connection, my fault--apologies to all! 21 Nov -Got Kohree dimmable-very nice!
------------------------

The other day I swapped out a standard dual ceiling light in the camper for an LED version. It was working fine on battery or at 13.6v at home.

Then had to charge the batteries so got on shore power with the converter at 14.7v. Very soon after the LED light went out and won't work on any setting for the two halves or to both ends at once. The other 12v lights (Non-LED) and fans etc all work.

Is it possible the 14.7v killed the LED lamp?

* This post was last edited 11/21/20 03:17pm by BFL13 *   View edit history


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Lwiddis

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Posted: 11/12/20 07:50pm Link  |  Quote  |  Print  |  Notify Moderator

Did the LED manufacturer give you a range of acceptable voltages? Usually on the package or in the “instructions.”


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RLS7201

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Posted: 11/12/20 08:03pm Link  |  Quote  |  Print  |  Notify Moderator

It's possible the LEDs you purchased will not tolerate the higher voltages. I have 18" ceiling LEDs in our MH and they have seen as high as 15.4 volts with no issues. You may want to ask the voltage question with your next purchase. eh?

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ktmrfs

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Posted: 11/12/20 08:31pm Link  |  Quote  |  Print  |  Notify Moderator

the el chepo LED lights use a resistor to set the current to the LED. Problem One. LED's should be driven by a constant current. When the voltage goes up, with only a resistor to control current, current goes up. Then LED junction voltage goes down, further increasing current. You end up with thermal runaway, LED's can get hot enough to melt the solder joint or just fail.

Good LED lights are more expensive, driven by constant current and generally say input voltage of 10-24V or more. Down side is the poor designed ones last a long time but put our RF that can interfere with radio.

14.7V is more than enough to kill the cheap LED lights.


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MEXICOWANDERER

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Posted: 11/12/20 08:36pm Link  |  Quote  |  Print  |  Notify Moderator

LED lighting for RVs is still in it's infancy.

I have built LED emitters that stay cool and blast out high noon amounts of light on 2-watts consumed. The problem is the sizes of the heat-sink and 3.7 volt regulator. Properly built there just aren"t any reasons for these lamps not to work for decades. According to friends a 5 mm red emitter I set up on the coast in 1981 is still 24/7. That's 39 years. It's mounted on a service drop box.

BFL13

Victoria, BC

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Posted: 11/12/20 08:45pm Link  |  Quote  |  Print  |  Notify Moderator

The reviews are from happy RVers. Maybe nobody with 14.7 volts!

https://www.princessauto.com/en/detail/1........n-led-interior-vehicle-light/A-p8488702e

pianotuna

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Posted: 11/12/20 09:12pm Link  |  Quote  |  Print  |  Notify Moderator

14.7 can kill an led DAMHIK


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wa8yxm

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Posted: 11/13/20 02:13am Link  |  Quote  |  Print  |  Notify Moderator

Some LED's are well designed and 13,14, 15, 16 volts wont' bother them
Others are **** in the design department
Some are even worse.

My RV came with an LED to light up the grab handle. Nice and looked good save the design was ****.. It burned out very fast.. I replaced it and .. Same result. it burned out fast too. (NOTE I replaced just the LED)

I then measured the resistor that limited current to the led 150 ohms. should have been 450 by my calculation. Replaced both the LED and the Resistor. 14 years later it still worked.


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Gdetrailer

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Posted: 11/13/20 07:57am Link  |  Quote  |  Print  |  Notify Moderator

BFL13 wrote:


Is it possible the 14.7v killed the LED lamp?


Yes.

There are three different types of LED light setups..

1 As one poster mentioned, many cheaply built LED assy's use a resistor as a current limiting device. This type of LED light has a very narrow voltage range that it will work fine within. You always can go down in voltage (dimmable) but go up and you let out the smoke packets that the factory put in it.. Once the smoke packets escape, the device no longer works.

Common, cheap and effective although you do lose some energy as heat through the resistor.

2 No current regulator (IE no resistor), only the LEDs wired in series and the LEDs themselves regulate the current.. Does work, however they have an extremely tight voltage range and going even a millivolt over can cause failure, can always go down in voltage (dimmable).. Typically used a lot with battery powerd flashlights but I have seen that design in line powered LED lights.

Common, cheap but pretty scary..

3 Electronic constant current/voltage regulated (switching regulator)with LEDs wired in series/parallel strings. Very efficient, tolerates extreme wide voltage variations (IE 9V-30V) without the LEDs changing brightness. These however are typically non dimmable).

Here is a pix of a G4 base LED for puck lights..

[image]

Not so common for vehicles and they are more costly, also have additional side effect of creating a lot of RF noise (RFI, "hash", ect) especially with poor designed regulators which can affect radio abd TV reception.

I suspect that you ended up with number 1 or number 2 options..

If it does not give you a large voltage range like 9-30V pass it up, it was designed for use with a vehicle which typically reaches 14.4V right after startup and that lasts for only a second or two.

BFL13

Victoria, BC

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Posted: 11/13/20 08:24am Link  |  Quote  |  Print  |  Notify Moderator

Will it still fry if it is turned off? If not, I could use the same type and make sure it is always off when the charger is at 14.x or when Pin 4 is live with the truck engine on. Solar too. (Not ideal!)

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