Home LED lights

[alldodge]

They do make outdoor LED Drivers that output DC
http://www.amazon.com/Waterproof-Tr...98762&sr=1-6&keywords=led+outdoor+transformer

Go figure, wonder if you can get the same distance away from the source? The light packages at HD and Lowes appear to be the same as what I have. From looking about everyone is going to the solar powered outdoor lighting. So far I don't want to go that route because I have not found any of them that last, cheap crud.

Thanks for the offer on the chips but I'll keep messing with what I have. Maybe something else will come along that will last and not use as much power.

 

[bruceb58]

Well, of course you will get voltage drop. Just have to calculate what that will be based on the line drop. Why it's always good to do a few star outputs vs one long line.

 

[StarTed]

bruce58's comments made me think about some LED light strings I bought that were made in China. These were under the car lights that I decided to use in a camping trailer I built. I figured that the 12V from the deep cycle battery in the trailer should be the same as the 12V from a car battery so they got wired in and provided adequate lighting for getting around inside. It wasn't long before some of these LEDs began failing. They have pretty nice little lenses on them that spread the light nicely so I like that part.

I ordered a pack of 100 super bright LEDs from China for a few bucks. They came with enough specs to figure the resister value needed. I tore apart a couple of the failed LEDs and discovered that they were driving them too hard. I think that they assumed that 12VDC is the absolute maximum without accounting for voltage rise when charging. I replaced all the LEDs with the new ones and new resistors that I calculated to be proper for 15VDC to allow for charging rise. So far, no failures and they are at least as bright as the original ones were.

I wonder if the manufacturers aren't driving the new LEDs to the maximum in order to try to meet their desired lumens. Sometimes marketing gets in the way of good design,

Just some thoughts.

 

[alldodge]

For some of the lights is the LED burning out or just cheap assembly process and corrosion causing it. Unable to say with the ones you mentioned but many of the flashlights I take apart, it's broken connections due to corrosion

 

[gm280]

LEDs can be finicky little devices. If you seriously want to calculate the best resistor for any LED, you have to read the actual drop across each one and then do the calculations. Because even though they look alike, different manufacturers use slightly different procedures and can cause different voltage drops across them. And when calculating that drop resister value, try to go to the middle of the current capability and not the max. That way the life expectancy will be long. I can't complain myself. I've been using some outside low voltage LEDs lights now for a long time and they still shine without issue. So I guess I just got a good batch. :noidea:

And I also have the very last (furthest from the supply source) LED shine just as bright as the first one. So it seem there is so little voltage drop along the line that it isn't effecting the current in the least. I think the wire is 12/2 stranded copper. And that run is about 100 feet in length. My only real problem I have is that ants love to built their mounds around the lights. And then they get inside and cause problems that way. So I have to try to kill the mound and then clean out the ant population a few times. JMHO!

 

[lakelover]

No help to your question, but this is exactly why I have not bought any LEDs. Sure, the bulbs last forever and that's what they advertise, but you don't know what you're getting for electronics. I'm all switched out to CFLs and will likely stay that way until I believe in the LEDs. In my experience, the CFLs do last longer than incandescents and they usually have a 6-7 year warranty...so I haven't paid full price for a CFL in about 8 years.

 

[bruceb58]

No help to your question.

Yes...off topic. CFLs are junk.

 

[H20Rat]

bruce58's comments made me think about some LED light strings I bought that were made in China. These were under the car lights that I decided to use in a camping trailer I built. I figured that the 12V from the deep cycle battery in the trailer should be the same as the 12V from a car battery so they got wired in and provided adequate lighting for getting around inside. It wasn't long before some of these LEDs began failing. They have pretty nice little lenses on them that spread the light nicely so I like that part.

What kind of power converter do you have on the trailer? I did a LED retrofit in my 1986 RV, and nearly every single LED was dead within 2 camping trips! Turns out the ancient power converter floated the voltage upwards of 16+ volts! (lots of those older inverters/chargers/converters also had a notorious reputation of cooking batteries if you left it connected to shore power too long.)

But yes, 12v is 12v, if that is truly what you have at the bulb. Generally low voltage shouldn't affect a LED, but worth measuring. They are very, very sensitive to high voltage though.

 

[MTboatguy]

What kind of power converter do you have on the trailer? I did a LED retrofit in my 1986 RV, and nearly every single LED was dead within 2 camping trips! Turns out the ancient power converter floated the voltage upwards of 16+ volts! (lots of those older inverters/chargers/converters also had a notorious reputation of cooking batteries if you left it connected to shore power too long.)

But yes, 12v is 12v, if that is truly what you have at the bulb. Generally low voltage shouldn't affect a LED, but worth measuring. They are very, very sensitive to high voltage though.

Hmm, I converted my 5th wheel interior lights to 12v LED that are a warm color 3 years ago and have not lost one yet, they work great, in fact last winter when I put it into storage, I left one of the lights on and didn't notice it until spring when we went to get it ready for camping season and it was still going strong, so that light was left on for over 4 months and still works fine, in fact the batteries didn't even run down, they were still at almost full charge, not much less than they would have been from just sitting. My 12v system is directly connected through the power bus to the batteries, if it is not plugged in, the converter does not come into play.

 

[H20Rat]

Hmm, I converted my 5th wheel interior lights to 12v LED that are a warm color 3 years ago and have not lost one yet, they work great, in fact last winter when I put it into storage, I left one of the lights on and didn't notice it until spring when we went to get it ready for camping season and it was still going strong, so that light was left on for over 4 months and still works fine, in fact the batteries didn't even run down, they were still at almost full charge, not much less than they would have been from just sitting. My 12v system is directly connected through the power bus to the batteries, if it is not plugged in, the converter does not come into play.

Yep, it was only an older converter system used in the 80's as far as I know. I put in a new converter system to solve the high voltage issue, I used the excuse that the new one also had a built in inverter and transfer switch, so it was a nice upgrade!

 

[StarTed]

smokingcrater,

My camp trailer doesn't have a converter. I use a Schumacher battery charger that I leave connected. It has 15 amp, 6 amp and maintenance selections as well as AGM battery selection available. I use the 15 amp selection if the charge % reads low from running my furnace all night off line.

LEDs are current devices but have a forward breakdown voltage that must be met in order for them to conduct and light. The problem is without some kind of current limiting the current can easily rise too high and destroy it. An interesting note is that an LED will operate more dimly with very high resistances in series as long as the supply voltage is above the required forward voltage. An example is that I run a red LED in series with a 33,000 ohm resister on 12 volts continuously in my pickup canopy. If the LED didn't conduct then there would be no voltage drop across the resistor so the LED would see the supply voltage. Of course that doesn't happen so the LED conducts and glows dimly.

 

[bruceb58]

LEDs are current devices but have a forward breakdown voltage that must be met in order for them to conduct and light.

No such thing as a forward breakdown voltage for a diode. Maybe you meant reverse voltage.

No LED bulb that you purchase as a consumer will require you to even worry about the forward current of the LEDs as long as you are operating the bulb with the spec's voltage.

The OP is having a problem with running 12VDC LED bulbs on an AC power supply. I can pretty much guarantee that most commercial bulbs are not using dropping resistors like was done with individual red LEDs that came out in the 80's.

My camp trailer doesn't have a converter. I use a Schumacher battery charger that I leave connected.

Battery chargers are a very poor choice to use as a power source unless you are only powering 12V light bulbs. They have a ton of AC ripple that can damage some electronics.

 

[StarTed]

I'll stand corrected for using the wrong terms. Thanks bruceb58 for setting this correct for others that may read this.

I'm not using electronics in my trailer at this time other than the battery charger. Just lights and and old Suburban furnace. My D cell transistor radio picks up plenty of noise when the generator runs so I can't tell if the battery charger adds to the noise.

I was referring to the forward voltage needed by the individual LED that is used to calculate the resistance needed to keep the current within the LED's range. The string of under the car LEDs that I purchased made in China had a resistor in series with each LED. Not the best way to do it but that is what that manufacturer used for current limiting. The individual resistors allowed the current to rise too high even for a car when running and the battery was fully charged. I was referring to the possibility that a manufacturer sometimes does things "on the cheap" to seem more competitive.

I have an old converter lying around that I'm thinking of installing but just never got around to doing that.

I built a battery charger for a previous camp trailer that I used and never had any problems even leaving it on for extended periods (years) without loosing battery fluid level. It was built using 2 SCRs and the voltage was stable enough to adjust to 2 decimal places. I kept it at 13.8 V and experienced no corrosion or battery acid level losses. Of course 13.8 volts won't charge a battery very quickly. I don't know if it would be a problem with electronics because that old Apache camp trailer didn't have any.

 

[bruceb58]

Most good led strips do not use current limiting resistors. There is usually a current regulating IC in the circuit.

 

[StarTed]

A current limiting IC is much better and uses less power. I just wanted to point out that there are some poor quality consumer products out there and it's hard to tell them apart by just looking at them. Marketing is a lot about hype and looks.

 

[NYBo]

How can an LED draw more current than it can use? I thought electrical devices only drew what they need, regardless of what is available.

 

[StarTed]

A LED has a maximum current rating. It can operate at less current but some devices keep the current near maximum and regulate the energy used by shutting them off a percentage of time. If they are shut off and turned on fast enough our eyes and brain don't see the flicker. That's one way to make them appear to dim.

Another way is to increase the resistance in the circuit but that wastes energy due to the resistance consuming some of the energy. Using resistance is old technology so that isn't used very much any more. In an AC circuit one could use impedance but that is equivalent to resistance in DC. It's better to use an IC circuit to turn it on and off very fast controlling the length of the on and off cycles.