LED Drivers

[mrlee]

Hi, I have an issue with LED drivers...I bought some of the recessed LED lights from China off of ebay. I have used them and experimented with them in the house for longevity, heat buildup etc...they seem to be pretty good as far as I can see..so, I want to install them in my sailboat. My question is how to drive them. They come with drivers for the house (85-265V AC) I have searched everywhere for a driver but since I have 9, 12, and 15 Watt Lights it is difficult to figure out the amperages for each.
I know there are a lot of very smart people on here as I have read a lot of threads on many subjects -by the way guys..THANKS for the knowledge sharing-
Who can steer me in the right direction here?
Thanks again y'all....God Bless

[leftbrainstuff]

LEDs for mains voltage tend to have large heat sinks. We have Lunasea LEDs throughout which don't need the heatsinks and run cool. We use 1Watt for ambient lighting and 3 Watt for working lighting.

Why are you wanting to adapt household LEDs to low voltage rather than just use low voltage LEDs?



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[mrlee]

Hi, thanks for the reply...I have been selling these recessed LED's in Mexico and I have a ton of them at my disposal. They all have heat sinks and I have adapted a small fan to the top of the 12 and 15W lights...These lights are great! I am making wood cabinets for them to be installed at the angle of the roof/ceiling to the side bulkheads and with the angleing capabilities of the LED's. it gives them quite an all around usefulness.
I like a lot of light...I am 64 now and as I go on I only think this will be more enhanced with the natural eye aging process...AHHH to be 45 again!!! Hence my need to use a 12V DC driver. I have just ordered 2 of them and my electronics friend has told me it is not a big deal to make a driver since the LED's are 12V DC anyway. He showed me one with an RCD-12, a cap., and a resistor...this is not my forte'...
So I was asking to see what you guys were doing...My problem is that I do not spend USD...I have Mex. Pesos...so a budget is first and foremost...the price we pay to live in paradise... all_as@hotmail is my email...if you would like..email me and I can send you some pix of my projects for my 26 Balboa. This is my hobby and my fun...I enjoy making things and I try to make everything I can so I don't have to buy it...weird part is...I won't have the boat til next week...customs etc...you have to pay the right guy here for EVERYTHING!!
I await your email...thanks again for the reply...let's communicate as I have a few questions for you...like 1W??? I find 12W a bit difficult to see with...

[CarinaPDX]

I'm not sure where to start with this. The only part of your LEDs that will be useful are the LEDs themselves and maybe the heat sinks - the circuits are all wrong. It is possible to design a proper drive circuit for a boat's 12VDC system, but that requires some engineering skill and access to the appropriate driver ICs. There are some pretty cool driver ICs available now, but do you have the ability to design the full circuit? I really doubt that it would be worth it to attempt on your own.

My recommendation: if you have 120V LEDs around, sell them and use the money to buy lamps intended for the application.

FWIW getting a marine LED right is not easy, and there are a lot of poor quality products out there. The best can handle broad input voltages without affecting output or durability, and without creating RF interference to your radios and equipment; the rest, not so much. Your friend's design falls squarely in the latter camp - the output will vary as the battery voltage varies, and if you are not careful a 14.2VDC charge voltage could shorten their lives. BTW there is no such thing as a 12V LED: LEDs are diodes with about a half volt drop, and are adapted for 12V in simple circuits by putting them in series with a limiting resistor. The result is a design that we warn everyone away from buying - do you really want to build one?

I don't mean to put a wet blanket on things, but this really is a project for retired engineers with too much time on their hands. The rest of us (even retired engineers who value their time) just buy the stuff - for marine gear it is pretty cheap.

Greg

[wingless]

The LED implementation needs to be selected for the application.

There are many ways to drive an LED. The low-cost solution is a series current-limiting resistor. But, the method I've used instead w/ very good results is to use a transistor in constant current mode w/ a current sense resistor. Another nice option is a this A6260 Allegro current regulator and this 9082 Surfboard.

If a single LED will be driven off the 12VDC nominal voltage, then a series resistor is often not a good choice. Assuming 2V across the LED, then 10V will be across the resistor. For a high-power LED, drawing 50mA, then the current limiting resistor will be consuming ½W. It doesn't sound like much until it is dumped into one small part, then it becomes burning hot.

A much better choice is the transistor in constant current mode or the A6260 Allegro current regulator. Both of these solutions avoid any really hot parts.

A better option is to put multiple LED parts in series, like four or five LED parts in series, then using one of these methods to limit or control the current.

[mrlee]

Hi guys...ok here's what I've done...I have run a string of 4 of these (9W,12W, &15W) in my shop...NO issues with heat...nothing. I measured the output of the drivers and here's what I found...
9W- 5-9V DC with ALL 700mA -checked about 7 different lights
12W- 5-9V DC with ALL 950mA-checked about 5
15W- 5-9V DC with ALL 1200mA-checked about 8
Everything I read on the internet tells me the amperage is the critical part of the equation. So, I have found drivers for the 9W LED's...when I get them I will connect a string of 4 and see how well they work, check for heat etc. I hope to have the 12 and 15 Watt drivers by then so I can run a circuit just like the one that will be in my boat to see how it works.
Each side of my boat will have a separate circuit ith 2-12W, 2-9W &1-15W LED's. My electronics friends tell me 1 circuit is sufficient for both sides...what do you guys think??
I have made a 30W LED light as well...These are BRRIIIGHT!!! the flimsy driver overheated so I have ordered a few of these drivers as well. I have a ton of ideas to install all LED's on my sailboat...and it will happen but after I test it all out first. all_as@hotmail
Email me and I can send you some pix of all my projects. Hey, maybe you'll see something you like and it'll help you...I am not an engineer, but I have built quite a few things in my time...
Thanks to all of you for the support...If you see anything I should know or I am overlooking...PLEASE...gimme a holler...
Be safe and happy with wind in yer sails...God Bless!

[mrlee]

OH, just a quickie to wingless...the transistor in constant current mode is pretty much what my electronics friend has come up with. He tells me the volts are easy so we just have to come up with the correct amperage for each LED...ohms law stuff I guess.
Thanks

[wingless]

Originally Posted by mrlee

I am not an engineer, but I have built quite a few things in my time...

Stay at a Holiday Inn Express last night?

Holiday Inn Express Korman's Enigma

Originally Posted by mrlee

OH, just a quickie to wingless...the transistor in constant current mode is pretty much what my electronics friend has come up with. He tells me the volts are easy so we just have to come up with the correct amperage for each LED...ohms law stuff I guess.

Yes, also ensure the watts are okay.

[goboatingnow]

Power dissipation in the transistor hence junction temperature is the key issue to driver survivability.

This is why many cheap drivers go west. The heat of regulation cannot be carried away.

Of course switched mode helps but then you get RF issues.

Dave

[mrlee]

Hey guys...I think I have this together but do you want to hear something CRAZY!!! On the 15W LED the data is: INPUT: 85-265V AC, OUTPUT 5-26.6V DC 350mA....WHAT!!! I only have 3 out of 18 15W lights with the info on the driver box...So, I experimented...I connected the driver to a charger for my cordless drill-25V DC with 500mA...it worked. It had the brightness of a 12W LED connected with its correct driver...so I let it stay on...for 3 hours it ran as I frequently checked it...NO heat ANYWHERE!!! The 9W and 12W would not light up at all with the charger...This kind of makes me CRAZY!!! I have no idea why this ran except that maybe because the mA's were in the ballpark.
The more I play with these...the more I don't get it...I need to get the 12V DC drivers and go from there and stop all this confusing playing around!
Any input here??

[wingless]

Links to the components please.

[mrlee]

Hi, I don't know the link but on ebay just search for:
Ultra Bright 15W CREE LED Cabinet Down Light Lamp Warm Day White bulb AC100-265V
These are pretty nice lights...all aluminum with nice heat sinks. I will remove the spring clips and put in 3 countersunk holes for st.st. nuts and bolts... I buy 3-5 per week and I sell them in Mexico...the shipping is free too...
As you can see, this is the 15W. If you email me I can copy and paste all the other stuff and send it to you...I have LED drivers with chips...30W and 50W...underwater LED's-10W (12V DC!!) muchas cosas....too much stuff...
Gotta run to class...later

[wingless]

Yes, that 15W Cree LED lamp has an external driver, that accepts 85-246VAC input.

[wingless]

Originally Posted by mrlee

On the 15W LED the data is: INPUT: 85-265V AC, OUTPUT 5-26.6V DC 350mA.

Those numbers on the driver box do not make sense.

The driver nameplate rating 26.6VDC output at 350mA is only 9.3W, not 15W.

Use a multimeter to measure the current, into the LED lamp and to measure the voltage on the lamp terminals.

[mrlee]

Hi, I need to check these with the light connected and on...under a load..correct? I tried to test the drivers this mornings and the voltages were all over the place...I had no luck with getting an Amperage reading as it was just the driver. I hear ya on the math not working out but why did this 15W LED run GREAT off of a 12V DC charger for a cordless drill?
I just spoke to a guy in China who will make these drivers for me...I will buy 1 of each to test them over a prolonged period of time to see how they perform. I am VERY heat conscious and I have even added small fans to the 12 and 15W LED's. I really like the heat sinks on these and the all aluminum construction...For Chinese junk, these are ok.
Check these out...
New 10W Underwater RGB Light LED Remote Control Spot Light Lamp waterproof
I wouldn't get the RGB-multi color- option again...There is another piece you have to buy to make the remote work so just get the white...These lights are very well constructed and they work well...12V DC!!! I have 4 for my shroud downlights. and maybe 2 installed as flush mount transom lights...It would be east to french them into a transom...