# Questions RE: Installing Interior 12v LED Light Strips



## Doc_V (Aug 11, 2012)

I'm interested in adding some interior accent lighting inside the cabin of my sailboat using 12v LED Strips. I'm referring to the flexible type that come in 16ft spools with 3M adhesive backing.

My question is, if I wire them directly to the battery, via the existing interior lighting circuit, other than a fuse, do I need to add any resistors etc.? I saw somewhere that a power conditioner is recommended, however they look to run about $150+ and I'm looking to do this on a budget. Is the conditioner absolutely necessary? Are there any less expensive options?

Thanks for any and all help.

Doc_V


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## johnnyquest37 (Feb 16, 2012)

I've got 12v LEDs in all my overhead light fixtures. Do not have a power conditioner. Seems to me you should be able to tap into the existing light circuit.


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## MikoBee (Sep 22, 2011)

On the ones that I have, you can see the resistors (little rectangles with numbers). I'd post a picture, but I don't have enough posts yet (google "sparkfun 10260", it's the first result). I suspect yours have something similar. If so you don't need to add resistors. 

I don't know anything about conditioners, but my intuition is that power coming from the battery bank should be pretty clean. It might be different if you were running straight from the generating source. Perhaps someone who knows what they're talking about can bring some actual information on the subject though.


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## svzephyr44 (Jun 26, 2000)

I use the LED strips available at auto parts stores for cars. They work fine. I wire them directly into the lighting circuits. One issue I have not addressed is their low current draw. The old circuit breakers are much too big - I may go back and add very low tubular low amp fuses to the circuits in front of the lights.


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## Doc_V (Aug 11, 2012)

MikoBee said:


> On the ones that I have, you can see the resistors (little rectangles with numbers). I'd post a picture, but I don't have enough posts yet (google "sparkfun 10260", it's the first result). I suspect yours have something similar. If so you don't need to add resistors.


Yes, the type I'm referring to does have resistors built in to the strip, like this:










...But I wasn't sure if they needed anything from the power supply. So you do have those on your boat and you've run them directly off the battery?



svzephyr44 said:


> I use the LED strips available at auto parts stores for cars. They work fine. I wire them directly into the lighting circuits. One issue I have not addressed is their low current draw. The old circuit breakers are much too big - I may go back and add very low tubular low amp fuses to the circuits in front of the lights.


Is there anything between the light strip and power supply on yours? Just wondering if they might have already added something since it's designed specifically for auto use. I'm planing to buy the LED strip in bulk 16 foot reels, so you have to solder your own connections I am planning on also adding an inline fuse, but not sure which amperage, I'd imagine something pretty small. Any ideas how much is needed?


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## MikoBee (Sep 22, 2011)

Doc_V said:


> So you do have those on your boat and you've run them directly off the battery?


My boat is much too small for those lights. I just run mine from a 12v power supply at home. You don't need any more resistors.


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## paperbird (Sep 1, 2011)

As long as the input voltage on the light strips is 12V, no reason to do anything but wire them to the lighting circuits. I'm sure you remember that LEDs lights care about the polarity. I've been looking at some gooseneck reading lights that are set up for a 4V input voltage. To use them, I'd have to add a resistor. And I hate the idea of drawing more current and converting it to heat. So I'll keep shopping for 12V gooseneck lights. (yeah - they probably have the same resistor internally, but at least I didn't add it...)


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## Maine Sail (Jan 6, 2003)

svzephyr44 said:


> I use the LED strips available at auto parts stores for cars. They work fine. I wire them directly into the lighting circuits. One issue I have not addressed is their low current draw. The old circuit breakers are much too big - I may go back and add very low tubular low amp fuses to the circuits in front of the lights.


The circuit breaker is to protect the wire not the lights. As long as the wire to the new LED lights is the same size it was then you can keep that breaker. If you stepped down to a smaller gauge wire and the breaker exceeds that wires ampacity then an additional fuse would be necessary to protect the smaller wire..

To do LED's correctly the need current regulation. Good LED's will have this built in, and you'll pay more. In strip or roll form many don't have any current regulation and require and additional circuitry so as not to overdrive them, heat them up and burn them out early.

Good LED's, that will last, use constant current circuitry

Cheaper LED's, that won't last as long, use a buck converter

The cheapest LED's, that can actually catch on fire, use a resistor to try and control current. Don't buy "resistive" controlled LED's..

Be careful what you buy when it comes to LED.


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## svzephyr44 (Jun 26, 2000)

Thanks Maine Sail - good info


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## Bruce_L (Jun 19, 2012)

I hope I am not violating any forum rules here... let me know if I do please, BUT, you can get awesome deals on 12 V led Strip lights at a place I get my radio control airplane parts called Hobbypartz.com They have both warm white and bright white as well as blues, reds, green etc. 

I buy the strip of 12 (qty) light set for $2.90 and make my own mount... They work great directly connected to 12volts no problem. 

The warm whites simulate a regular incandescent bulbs color spectrum pretty good.

Try a blue strip mounted under a seat or cabinet edge for a pretty look against white gelcoat at night.

The current is really low so you can use very small wire to operate them as well.

I do a lot with LEDs since the power consumption is so low.


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## Ritchard (Aug 15, 2011)

I had great luck with that bulk strip lighting. I just tapped into the existing lighting circuit. Warm white strips hidden behind shelf fiddles look fantastic. However, Main Sails comments are worrisome.


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## Doc_V (Aug 11, 2012)

Maine Sail said:


> The cheapest LED's, that can actually catch on fire, use a resistor to try and control current. Don't buy "resistive" controlled LED's..
> 
> Be careful what you buy when it comes to LED.


Are these what you mean by "resistive controlled"? They appear to have resistors built in to the strip. Are they the so called "cheap ones that catch fire"?


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## Brewgyver (Dec 31, 2011)

That LED tape is fine, just the way it is. An in-line fuse is always a good idea. To calculate fuse ampacity, check the spec from the manufacturer, several of the ones I checked were 24 watts for a 5 meter tape, which would be a 2 amp draw at 12 volts, use at 2.5 or 3.0 amp fuse. White LEDs are usually higher current - saw one on a quick search that was 14.4 watts per meter, or 72 watts for the 5 meter roll. That would warrant a at least a 7.5 amp fuse. I've actually had good luck finding low amperage glass tube fuses at Home Depot.


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## asdf38 (Jul 7, 2010)

Maine Sail said:


> The circuit breaker is to protect the wire not the lights. As long as the wire to the new LED lights is the same size it was then you can keep that breaker. If you stepped down to a smaller gauge wire and the breaker exceeds that wires ampacity then an additional fuse would be necessary to protect the smaller wire..
> 
> To do LED's correctly the need current regulation. Good LED's will have this built in, and you'll pay more. In strip or roll form many don't have any current regulation and require and additional circuitry so as not to overdrive them, heat them up and burn them out early.
> 
> ...


Resistors are a perfectly valid form of current limiting and for cheap LED products, really common. I design boards with LED's all the time and for low power and low cost the resistor is the way to go. The problem is only efficiency and brightness regulation. You're giving up both with tradeoffs between them if you use a resistor.

In this case, something like this strip can use resistors while still not consuming much power so it's not ideal but not something to particularly concern yourself with.

And to the original question if it's labeled as being for 12V...then it's for 12V (if it's a cheap crappy product that's a different problem). Don't add any more regulation - you could even cause a failure depending on how they are managing current (for example you can't have two current sources in series).

Maine, to add, a Buck is a switching DC-DC converter and if current controlled that would be ideal. "Constant Current" is ambiguous because it includes switching regulators (efficient) and linear current regulators (not efficient).


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## flyingriki (Sep 27, 2012)

svzephyr44 said:


> I use the LED strips available at auto parts stores for cars. They work fine. I wire them directly into the lighting circuits. One issue I have not addressed is their low current draw. The old circuit breakers are much too big - I may go back and add very low tubular low amp fuses to the circuits in front of the lights.


My understanding is circuit protection devices (fuses or circuit breakers) protect the wire, not the device. So changing CBs may not be necessary....

Aha, just saw the post above quoting Maine Sail - same thing.


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