24v lights on a 12v system?

[Intalleyvision]

A lot of LED lighting options I like are all labeled as 24v (like IKEA lights and what not). Can I just plug this into my 12v system or do I need some device to convert all my 24v fixtures to 12v before running everything back to my batteries?

[Tango]

To get full brightness, I believe you need to start with 12v LED bulbs (?)

[CaptSquid]

Running 24VDC bulbs on a 12VDC system gives you low output lights. superbrightleds.com has PLENTY of 12VDC LED lighting options.

[somewhereinusa]

You can make your own fixtures using cheap leds from eBay

[family wagon]

If you really like what you're finding but it requires something besides 12v dc (or whatever your battery bank's voltage may be), know that dc-dc conversion is easy. Search Amazon for "dc-dc buck" or "dc-dc boost" for voltage down- and up-converters respectively. There are also some "buck-boost" which can convert both up and down.

I'm looking forward to receiving in the next few days this $21 100W step-up converter, with both constant-voltage and constant-current operation which I'll use to drive this $10 absurdly bright 100W LED module. The module operates in the neighborhood of 30-34 volts, and the power supply converts 3-35 V input (ie, my 12 volt) to 3-35 V output. Haven't figured out yet exactly where or how it'll fit into the bus project, among other things, but surely I'll come up with something after playing with it!

Those converters on Amazon are relatively inexpensive, but potentially cheaply built too. A place like Powerstream sells a variety of dc-dc converters that are probably more rugged, come in a nice housing, may have higher power ratings, but unfortunately do cost more.

[CaptSquid]

Originally Posted by somewhereinusa

You can make your own fixtures using cheap leds from eBay

Just remember, you get what you pay for.

[Redbear]

LED lights require a current limiter to keep from drawing excess current. When the voltage is known, it may be as simple as a voltage-dropping resistor. This might be good off of a wall wart, but not so much on a vehicle that might vary between 10.5 and 15 volts, depending on the charging/discharging cycle.

Connecting a purely resistive load to half the voltage, the reduced electrical pressure will only draw half the current, meaning one quarter the wattage will be drawn. Look at the 250/125 switch on Bansil's hot water heater.

A lot of LED assemblies have switching power supplies to regulate the current. These change the amount of power drawn to match the LEDs needs. Look at the new laptop power supplies that work from say 80 to 250 volts.

It is entirely possible that the IKEA assemblies have switching supplies that run the LED strings at less than 12 internal volts. In that case you might get full brightness. Connecting the assemblies to under-voltage SHOULD not damage the assemblies. But if there is a switcher that adjusts for the voltage, it will draw more current for full brightness, and the current limiter might not be designed to dissipate the increased heat. This is like an inverter that draws off the batteries harder at 11 volts than at 14 volts to maintain a stable 125 VAC.

If you have money to throw at a science experiment, you could try one of the 24-volt assemblies at 12 volts to see what happens. If not, match the LED assemblies to the supply voltage.

[rossfree]

Redbear is on point. Led lights are great. Without getting too technical ( but I know I will) it's all about a current limiting resistor. LEDs look like dead shorts to electricity once they reach "Turn-on voltage". Small LEDs typically operate at 20 milliamperes of current. I'm not sure what the larger led currents are. But in simplest terms going from a 24 volt doc led light to a 12 volt dc bus requires that the current limiting resistor(s) be replaced with equivalent wattage resistor(s) at half the resistance. See... I told you I was gonna get technical.

Without looking at an IKEA 24volt dc light fixture, it is likely that the changing it from 24 doc volts to 12 volts dc would cost less than a dollar in parts. But I could not tell you how difficult the job of replacement would be without seeing it in person.

If you really like a particular 24vdc led light fixture, find someone locally that has some basic electronic skills and have him take a look!

And let the forum know what you find out!

Best of luck!

Ross