CONNECTING A PAIR OF 12V LED PLATES FOR 24V SYSTEM?

Need to check into some 2" X 3" device heatsinks and thermal adhesive. Configure mother convection to work for me. Anyone got a few dozen heatsinks like this laying around? I ran outside and checked under the banana plant but no luck...

JiminDenver wrote:
My panels are 1210 48 LED panels, 5050 are warmer. So far mine haven't had any heat issues. Also if you are speaking of the 3 m tape on the cheap ebay LEDs, it's fake . . .

Yeah, I know--pretty obvious---lol!! Bought a role of "real" 3M, both the regular and the heavy-duty outside version, and used this instead. Although the real 3M stuck better, it still turned brown after a few hours.

Mex

I ran the test for a hour and they stayed on. Actually the voltage of the bank was 25.3v. I have to say that they were running hotter than usual.

If all else fails, there are current regulated bright panels designed for 10-30VDC operation. That's the ideal solution, since LED's are really a current driven device. But then they come with a price.

superbrightleds.com has such 10-30V DC panels.

It's worth a try running two 12V in series. May or may not work out. Reason again is that LED's are current not voltage devices and if the panels are not exactly matched, one panel may have slightly higher/lower voltage drop across the LED's than the other, so one ends up with more than 12V and the other less than 12V. If they are close probably not a problem. If it starts to deviate much, then you risk the higher voltage panel going into thermal runaway.

What I would do is hook each 12V unit up to a battery, let it stabilize for temp, then measure the current draw. Try to match panels that draw as close as possible the same current draw. That way you will at least start with "matched pairs".

the better you can heat sink them, the better off you will be. forward voltage drop is a very strong negative function of temperature, and as temp goes up, forward voltage drop for a given current goes down and with resistor limited panels that means current starts going up, power goes up, Vf goes down more..... Mex, I think you'll get the picture!!!

My panels are 1210 48 LED panels, 5050 are warmer. So far mine haven't had any heat issues. Also if you are speaking of the 3 m tape on the cheap ebay LEDs, it's fake.

When ever I install 120v LED lights for people, there is always a warning in big letters to not install the LEDs in unventilated fixtures and they usually have heat sinks. How many RV fixtures are ventilated? Some small vent holes in the lens might work wonders.

Mex

the test is running and boy are they bright. Any numbers that you want from a basic MM?

JiminDenver wrote:
I have some extra panels downstairs and could set up a simple test of two in series on two 12v batteries in series if it will help. These would be the el cheapo 10 for $17.99 panels if that makes a difference.

Looking at ebay there are also led panels listed that will work off of 12 or 24v.

I have a few of these eBay LED panels, too (20, 5050 SMD LED's). Cannot comment on whether they'll operate in series on 24 vdc. But, they do put out quite a bit of heat--enough to brown double-sided 3M tape when mounted inside an enclosed TT light enclosure.

The trick is to prestidigitate a pair all the way over her from China. I can grab stuff from the PO box one or two times a year now. Too many birthday candles means I gotta stop putting things off until mañana (sigh)

LED systems come in basically two or three types

One type starts with a series resistor, and then the LED and that's all folks. This type, you put two of them in series, and it should work as you hope it will.

Some have voltage regulators, ahead of the series resistor, This one may well work on 24 volts without any mod (However I do not recommend it)

Some have a CURRENT limitere ahead of the led.. Same as the voltage regulated ones,,, And these should work in series as well (All 3 kinds should).

THe key is, as someone said up above, to keep the two assemblies the same.

Cause if one takes a bit more current, the other won't last long.

I have put LED's in series more than once.

NOTE: If you see a difference in the two LED's in the pair.. Try putting a resistor across them. say about 1,000 ohms. (That will cause 12mA to flow through the resistors) if it works, up it to 10,000 ohms (1.2mA) Like this.

Resistor-|--Resistor
--LED---=|==LED--

This is a fairly old trick, but it still works.

It's the first few milliseconds and then operation at 50C that I am curious about. In theory they should series fine. But I am planning to order 70 panels and it would be a shame (sob) to run afoul of reality. Thank you JimInDenver!

I have some extra panels downstairs and could set up a simple test of two in series on two 12v batteries in series if it will help. These would be the el cheapo 10 for $17.99 panels if that makes a difference.

Looking at ebay there are also led panels listed that will work off of 12 or 24v.