SSC P7 Driver for Auto application (14V)

Hi guys, i searched on this forum before but couldn't find answer on my question without asking questions. i got 4 SSC P7 leds (C bin 900lumen once, not from deal extreme). and want to use it as backup light in my Honda Accord. i found this http://www.kaidomain.com/ProductDetails.aspx?ProductId=1866 from links in other threads on this forum but problem is that it says no more then 12V in description.

maybe 12V for continuous use but they will be on for no more then 20 seconds at a time with long cool down time if it matters.

my question is, is it ok to run them at 14.25(which is what car output when car is running(i checked))??

i would run them with sharp voltage reg but max on the driver is 2A and not 2.8A which what led needs from driver for max output


im on hidplanet and couldnt get straight answer from ppl there.

i know im a noob but still


damn it. low output only 5% hmm. ok what are my choises in drivers to have at least medium output then high? is it possible to make driver relatively cheap or just easier to buy one?


this kinda **** me off that they say 15V and then say no more then 12V for board protection, false advertisement?

your link says Low/High/Middle,5.5V~15V

alpg88 said:

your link says Low/High/Middle,5.5V~15V

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well only driver one i found (i think i see other one before with just low and high mode). kinda good that its low first and high second. this way i when i back up it can switch on low mode first and i would run switch into inside of the car and if i need brighten up i can put on high (not always need high mode couse not always backup at night

I would want a single mode driver for that application.

Mark620 said:

I would want a single mode driver for that application.

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well maybe you right and i originaly wanted that but thought about it and maybe having 2 mode is better in terms that if i made this permanent change in tail light, i dont know about passing inspection with backup light that bright, i dont know what the rules on that is. i can always put my other lights in if needed.

got any single mode drivers in mind?

found this
https://www.candlepowerforums.com/threads/201981

The fact that it is going on an auto application means that the driver will be subject to a lot of noisy and spikey voltage. The only LED drivers that I know of with capability to withstand that are the ones from taskled.com.

HarryN said:

The fact that it is going on an auto application means that the driver will be subject to a lot of noisy and spikey voltage. The only LED drivers that I know of with capability to withstand that are the ones from taskled.com.

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looked. seen some but kinda looks complicated to use (hipflex)


i dont know what can be run in parralell or in series

Alright, my idea was to use the sharp regulator anyways. It's rated at 2A! I doubt that your LED will use more than 24W. I doubt that your LED and driver together will use more than 24W. I was hoping someone else would verify this, so that I don't feel bad when he fries his high-bin P7's, so I will provide the link to the regulator:
http://sharp-world.com/products/device/lineup/data/pdf/datasheet/pq05rd21_e.pdf

and now I will show you the math behind my thinking:

Power used must be less than the power made available using the PQ12RD21 12V regulator.

Power made available using 12V regulator. Well, it puts out 12V at a maximum current of 2A.
P=I*V
P=2A*12V
P=24 VA, or 24 Watts.

P7 is said to use 10W. I don't know if that's a good estimation, and I don't know much about your particular LED, but I do know that each die is rated at 700mA, and that the 4 dice are in parallel, so the LED should be run at 2.8A. Now, I don't have a value for it's Vf, but I am going to assume it's between 3.25 and 3.5V.

P=I*V
P=2.8A*3.5V
P=9.8W, so yes, 10W is a decent estimation.

Back to our original statement, the power used must be less than the power made available by our voltage regulator
Power available > Power used
24W>9.8W

So there's my logic. Is the logic sound? Only someone who isn't me can answer that

The sharp regulator does not have a feedback pin, so you can't adjust voltage or current.

Therefore it is not suitable for driving LEDs. If the voltage is too high,then the regulator will be destroyed. And if the voltage is too low,then the LED won't be driven with full power....

I thought the problem was that the driver that OP is using wants 12V, but his car is putting out 14.25V and he needed a way to feed his driver a less-noisy 12V. My bad.

And to clarify, I do not recommend using a sharp as the only regulation for high-power LEDs. They do, however, work great for regular and high-flux ones.

OP, you're SOL. Find another driver, or make one yourself with some 317s

bshanahan14rulz said:

I thought the problem was that the driver that OP is using wants 12V, but his car is putting out 14.25V and he needed a way to feed his driver a less-noisy 12V. My bad.

And to clarify, I do not recommend using a sharp as the only regulation for high-power LEDs. They do, however, work great for regular and high-flux ones.

OP, you're SOL. Find another driver, or make one yourself with some 317s

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how can i make one with 317s(whatever it is, or is it 3170)??

AV6NHBP6SPD said:

how can i make one with 317s(whatever it is, or is it 3170)??

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http://www.reuk.co.uk/LM317-Voltage-Calculator.htm

it is a voltage regulator, but you wanna use lm350 (good for 3 ams), 317 are only good for up to 1,5 amps, p7 will blow it
also when you calculate your resistor values, and power it on, connect dmm and you'll see correct voltage (3.5v it should be), however when you power it up and hook up your led you'll see v out at least 1v lower, draw will drop v out. what i usually do , instead of r1 i use a pot, than adjust v as i need under load, mesure resistance of the pot with a dmm, than replace pot with a resistor with the same ohm as pot was.

alpg88 said:

http://www.reuk.co.uk/LM317-Voltage-Calculator.htm

it is a voltage regulator, but you wanna use lm350 (good for 3 ams), 317 are only good for up to 1,5 amps, p7 will blow it
also when you calculate your resistor values, and power it on, connect dmm and you'll see correct voltage (3.5v it should be), however when you power it up and hook up your led you'll see v out at least 1v lower, draw will drop v out. what i usually do , instead of r1 i use a pot, than adjust v as i need under load, mesure resistance of the pot with a dmm, than replace pot with a resistor with the same ohm as pot was.

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somebody brought up interesting point on hidp

StupidPig said:

Well, from the link, the driver will only take 1.15A @ 11.1V, so I guess the sharp 12v Req probably work.

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so do i understand it right. it will take 1.15A in and put out 2.8A?

AV6NHBP6SPD said:

so do i understand it right. it will take 1.15A in and put out 2.8A?

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yes..

a better way to think of it is to compare Power. Amperage doesn't mean anything without voltage, and voltage doesn't mean anything without amperage. You could have a bazillion volt difference in potential, but with no current, nothing happens.

To calculate the power, simply multiply voltage by current.

The maximum POWER that the sharp regulator can supply isn't known, but we have V and max current, so:
12V*2A= 24W

Now, the amount of power your driver will require 1.15A at 11.1V. (I'm just taking values from the post above, if you have different values, use those) If you do the math:
11.1V*1.15A=12.765W
so that driver will use 12.765W out of the 24W made available to it.

So, that's the basics. I was going to try to use the water analogy, but I've never been good at analogies. Something about if your "current" through a large pipe is such-and-such, you get this volume of water but same current through a smaller pipe is that volume of water, I dunno, it's gone now...

gona go this route
http://www.instructables.com/id/Super-simple-high-power-LED-driver
efficiency not important

For protection against Automative spikes try adding a 1.5KE22A across the input. (available from Digikey etc)

To protect against spikes, couldn't you use capacitors for car stereo and have clean voltage?

This is what I used.

I used 8 P7s and did it in 2 parallel strings of 4. I had to use 2 circuit boards per 4 LEDs so you should only need 2. You could probably use some input filtering, like with some electrolytic capacitors.