High power LEDs in automotive applications

[MDKline]

Hi-

I'm working on a vehicle lighting application for work site safety (aka amber LED strobes or light bar). I have been doing some research and would like to use high power LEDs. However, having never used them prior to this, I have a few concerns.

I'm looking to use colored emitters with an output of ~60 lm each. I'm not sure if I need more than four emitters in an array (there will be a total of 8 arrays switched individually by a 12v flasher). I was hoping to make the light head a bit brighter than a standard automotive turn signal. Will this be enough/to much light? I've seen aftermarket tail light bulbs with 3 1 watt LEDs, and I will not be losing my output due to a filter (like indecent lamps). If I make it too bright, then it will blind other drivers at night.

I found some cheap Luxeon Rebels (LXML-PL01-0030) at Newark, but they are not on stars. This is not an issue except if I needed to use optics. I'm not sure I really need them. The windows are not tinted. With out the optics, I think there would be more of a flood pattern and thus a greater warning for vehicles not coming from directly behind. Is this reasoning correct?

Cooling will be aided by the housing (an aluminum channel) and thermal compound. This does not worry me as much as the power source. I would like to use more protection than just a current limiting resistor. I was looking for drivers with a wide range of input voltages. Since these are for safety, I still want the lights to flash even if the battery discharges below 12v. One source suggested a operating range of 9 to 16v for automotive drivers. Furthermore, I need a way to filter/protect the LEDs from high transient voltages. Any suggestions on how to do this? An IC solution would probably have the least parts. I'm new to this, so as much detail as possible would be appreciated. Any other thoughts/suggestions?

Thanks for the input!

 

[Ubergeek63]

Hi-

I'm working on a vehicle lighting application for work site safety (aka amber LED strobes or light bar). I have been doing some research and would like to use high power LEDs. However, having never used them prior to this, I have a few concerns.

I'm looking to use colored emitters with an output of ~60 lm each. I'm not sure if I need more than four emitters in an array (there will be a total of 8 arrays switched individually by a 12v flasher). I was hoping to make the light head a bit brighter than a standard automotive turn signal. Will this be enough/to much light? I've seen aftermarket tail light bulbs with 3 1 watt LEDs, and I will not be losing my output due to a filter (like indecent lamps). If I make it too bright, then it will blind other drivers at night.

indecent? are they nudie projectors? seriously though, 3 1W LEDs is meaningless, they could be anything between 30 and 100+ Lm each with only 1/4 the light actually getting through the color filter.

I found some cheap Luxeon Rebels (LXML-PL01-0030) at Newark, but they are not on stars. This is not an issue except if I needed to use optics. I'm not sure I really need them. The windows are not tinted. With out the optics, I think there would be more of a flood pattern and thus a greater warning for vehicles not coming from directly behind. Is this reasoning correct?

Cooling will be aided by the housing (an aluminum channel) and thermal compound. This does not worry me as much as the power source. I would like to use more protection than just a current limiting resistor. I was looking for drivers with a wide range of input voltages. Since these are for safety, I still want the lights to flash even if the battery discharges below 12v. One source suggested a operating range of 9 to 16v for automotive drivers. Furthermore, I need a way to filter/protect the LEDs from high transient voltages. Any suggestions on how to do this? An IC solution would probably have the least parts. I'm new to this, so as much detail as possible would be appreciated. Any other thoughts/suggestions?

Thanks for the input!

**broken link removed**

the auto power bus is NOT 12V, it is 14-16V with load dumps to 60V and low impedance spikes to 100V - there is a reason that automotive grade regulators have 60V breakdowns!

https://www.electro-tech-online.com/custompdfs/2010/04/autoEMC_paper_loaddump_may06_rev03.pdf which is why current limiting resistor based light bars are unreliable. Frankly while many hobbyists use 3023-D-N-350 Wired BuckPuck - LED Supply.com in cars, they are not rated properly for automotive either - you will not catch a mfg using them!

as to actual ICs my favorite is Supertex HV9910 ... flexible ext switch part that will run on 8-450V

 

[MDKline]

Thanks for the information!

As I said, I'm new to these things. I was thinking I would need one driver for each array. The light bar would work by illuminating the head on the right, then illuminating the first two on the right. Eventually it will continue to light-up all the heads, go out, and restart the pattern. With all LEDs l will be pulling quite a bit of power. I doubt I would be able to have just one HV9910 on the common positive wire to control all LEDs because they are not on all the time. Is this correct?

I think the only way for me to judge the brightness and need for optics would be to actually go buy some and test it out. However, with out being 100% sure I'm doing this right I don't want to actually spend the money.

BTW: Sory I ain't got no gud englash or speling

 

[nsaspook]

Hi-

I'm working on a vehicle lighting application for work site safety (aka amber LED strobes or light bar). I have been doing some research and would like to use high power LEDs. However, having never used them prior to this, I have a few concerns.

I'm looking to use colored emitters with an output of ~60 lm each. I'm not sure if I need more than four emitters in an array (there will be a total of 8 arrays switched individually by a 12v flasher). I was hoping to make the light head a bit brighter than a standard automotive turn signal. Will this be enough/to much light? I've seen aftermarket tail light bulbs with 3 1 watt LEDs, and I will not be losing my output due to a filter (like indecent lamps). If I make it too bright, then it will blind other drivers at night.

I found some cheap Luxeon Rebels (LXML-PL01-0030) at Newark, but they are not on stars. This is not an issue except if I needed to use optics. I'm not sure I really need them. The windows are not tinted. With out the optics, I think there would be more of a flood pattern and thus a greater warning for vehicles not coming from directly behind. Is this reasoning correct?

Cooling will be aided by the housing (an aluminum channel) and thermal compound. This does not worry me as much as the power source. I would like to use more protection than just a current limiting resistor. I was looking for drivers with a wide range of input voltages. Since these are for safety, I still want the lights to flash even if the battery discharges below 12v. One source suggested a operating range of 9 to 16v for automotive drivers. Furthermore, I need a way to filter/protect the LEDs from high transient voltages. Any suggestions on how to do this? An IC solution would probably have the least parts. I'm new to this, so as much detail as possible would be appreciated. Any other thoughts/suggestions?

Thanks for the input!

Check here for ideas on something that might work. www.autolumination.com Tail Light Brake Light Turn Signal LED Bulbs

 

[MDKline]

nsaspook: Thanks for the suggestion, but I have spent some time in the past looking at those options. If I were to purchase sockets and high quality LED bulbs, it would cost as much as most of the pre-made LED turn signals: ~$30 US. I figured I could make something with a lower profile for ~$15.

My original inspiration came from **broken link removed** , but the cost would be comparable to what I want to do with the newer LEDs.

 

[nsaspook]

nsaspook: Thanks for the suggestion, but I have spent some time in the past looking at those options. If I were to purchase sockets and high quality LED bulbs, it would cost as much as most of the pre-made LED turn signals: ~$30 US. I figured I could make something with a lower profile for ~$15.

My original inspiration came from **broken link removed** , but the cost would be comparable to what I want to do with the newer LEDs.

Because this is a work safety related item I would err on the side of possible liability. $30 is not a lot if somebody claims yours was a faulty design. My 2c from someone whose brother is a lawyer.

 

[Ubergeek63]

the HV9910 would handle the power no problem... it uses an external FET. that pattern could be done by shorting out the LEDs that you do not want to light and using a single driver to driver them, accept for the fact that you are using more voltage than the car's electrical system provides.

you could be sneaky and use a consumer 100W car inverter to drive the system. I personally do not like driving high power from boost regulators since you then need more expensive parts to get full power to prevent high current peaks.

 

[MDKline]

Because this is a work safety related item I would err on the side of possible liability. $30 is not a lot if somebody claims yours was a faulty design. My 2c from someone whose brother is a lawyer.

This is a second and non-integral level to a lighting system for personal use. There will also be an independently controlled and commercially available hide-a-way strobe system. So, if my design does fail there are other warning lights on the truck. Besides, just buying stuff just ain't as much fun.

Ubergeek63: Thank you for the confirmation. My plan is to connect the arrays parallel to one another and drive each individually with a HV9910.

 

[Ubergeek63]

This is a second and non-integral level to a lighting system for personal use. There will also be an independently controlled and commercially available hide-a-way strobe system. So, if my design does fail there are other warning lights on the truck. Besides, just buying stuff just ain't as much fun.

Ubergeek63: Thank you for the confirmation. My plan is to connect the arrays parallel to one another and drive each individually with a HV9910.

you will not be able to run them all in parallel. LEDs are current driven, connecting them in parallel will blow them out as the lowest voltage device takes the most current until it blows out after which the rest have that much more current and blow out faster.

you would need additional circuitry to force current sharing which would then eat into the efficiency and perhaps require heat sinking.

driving the Rebels at 700mA, if you sacrifice 1V for current sharing (a few tenths for current sense resistors, a few tenths for BJT Vsat, and a few tenths for LED variance) you should be able to still run 2 series to limit the devices required.

 

[MDKline]

you will not be able to run them all in parallel.

Sorry I had misunderstood your post from before.

 

[Ubergeek63]

Sorry I had misunderstood your post from before.

not a problem .... just the last thing you want to do is to pop even "inexpensive" Rebels!