20 watt "high power" led - direct driven in car? (no driver)

[lightime]

Hi,

I want to use a 20watt high power led to light up an amplifier rack in a car. Can I connect a 20watt high power led directly to +pos and -neg in the car? Do I need a driver?

Thanks in advance!

Below are the specs of the LED:

• LED colour: white
• Lens colour: clear
• Viewing angle: 140°
• Forward voltage [VF]: 13.5 - 15V DC
• Forward current [IF]: 1400mA - 1800mA
• Luminous intensity [IV]: 1000LM
• Colour temperature: 5500K
• Light diameter: 12mm
• Back plate dimensions: 22.4 x 15.5mm
• Back plate thickness: 2.5mm
• Entire unit thickness: 6mm

 

[-Virgil-]

Two thoughts occur to me:

1. I would be very surprised if this item, tested in the real world with reliable equipment calibrated properly, actually takes 20w and/or actually produces 1000 lumens.

2. You're not planning on having this thing lit up while you're driving, are you?

 

[1980Gabo]

I have used this item for my grade work, and I did actually driven them directly from the battery (no driver involved as you say). Two years since I began working with them, zero problems. I don't know if the output is really (or somewhere near) accurate...

 

[lightime]

Thanks for the reply. Nope....Won't be using when driving the car...only when stationary but the motor could be running so it could see a bit over 13 volts.

Not sure if it really produces that brightness. But assuming the specs of VF 13.5 - 15V DC and Forward current of 1400mA - 1800mA are correct. If I hook it up directly to pos and neg in the car which should fluctuate from 12-13.5 volts or so...would I see the max brightness at 12-13.5 volts or would I have to get closer to 15 volts to see max brightness?

Two thoughts occur to me:

1. I would be very surprised if this item, tested in the real world with reliable equipment calibrated properly, actually takes 20w and/or actually produces 1000 lumens.

2. You're not planning on having this thing lit up while you're driving, are you?

 

[DIWdiver]

You can hook this up directly to the vehicle power.

You will have to be at max voltage to see max brightness. But a 20% change in brightness is barely perceptable.

1000 lm at 20W is not state of the art, and very believable for this part. State of the art is 1000 lm at 10W.

You will need a substantial heatsink on this part to avoid overheating and destruction of the part. The smaller the heatsink, the more rapid the destruction. It could be anywhere from 10 seconds to 10 years. I would be looking for a heatsink with 40 square inches of surface area for operation in still air, half that in slow moving air, 1/4 or less in fast moving air. Heatsinks are often specified in C/W, or temperature rise in degrees C per watt of power dissipation. You probably want to plan on a temperature rise of no more than 50C. In reality it will be higher than you plan for. At 20W, that means you want no more than 2.5C/W at the minimum airflow you will see during operation. Note that 2.5C/W in still air takes around 40 sq-in of surface, as I originally said.

There are events which occur in vehicles that could potentially damage this device if it is not protected. When you turn off a large load, like the headlights, the alternator causes a surge in the supply voltage. In most cases this is not damaging, but in the worst case it could destroy your LED if it is connected when a 'load dump' event occurs. A proper driver will protect against this possibility.

 

[lightime]

Thank you very much for the reply! I really appreciate it. I will go ahead and try it out directly hooked up but will try to find a driver down the road.

Thanks again!

 

[Thr3Evo]

Maybe small power resistor might add a bit of insurance, heat sink this along with that led if u don't want to throw ur money in the garbage.