Thread: LED tail lamps

Use a special LED flasher can designed for LED lights

Off the top of my head. If normal globe is 21 Watt that is about 1.5 amps at 13.8 V. If we assume all the LEDs are in parrallel, LEDs need about 20 mA per LED if you have 50 off them then that will give you an Amp. Which is not that far away from 1.5 amps so would flash faster but not that bad. You must have less LEDs say you have 25 LEDs, that will be 1/2 an amp. That is going to require for you to put a load of 1/2 to one amp extra to get you can to flash at the same rate. 12 ohm which is a preferred value should do the trick. Just make sure that you get a 10 Watt resistor or make up the a bunch of 10 1 watt resistors in parrallel use of 120 ohm.

As was previously said use a flasher can for LED lights it will be easier and cheaper.

Originally Posted by slug_burner

Off the top of my head. If normal globe is 21 Watt that is about 1.5 amps at 13.8 V. If we assume all the LEDs are in parrallel, LEDs need about 20 mA per LED if you have 50 off them then that will give you an Amp. Which is not that far away from 1.5 amps so would flash faster but not that bad. You must have less LEDs say you have 25 LEDs, that will be 1/2 an amp. That is going to require for you to put a load of 1/2 to one amp extra to get you can to flash at the same rate. 12 ohm which is a preferred value should do the trick. Just make sure that you get a 10 Watt resistor or make up the a bunch of 10 1 watt resistors in parrallel use of 120 ohm.

As was previously said use a flasher can for LED lights it will be easier and cheaper.

To increase the current flow wouldn't you need to put the resistors in parallel with the LED's? If the resistors are put directly across the 12V cause the LED's not to work and the resistors to release the Lucas smoke we all try so hard to keep inside the wires? If you change the flasher unit you will most likely loose the trailer indicator light on the dash, this may not worry you, but i like to know the trailer lights are working on mine. One way around the problem you have is to fit an extra set of indicators on the bull bar etc. Inc should know a way around this, he sells them.

Originally Posted by jimbo110

To increase the current flow wouldn't you need to put the resistors in parallel with the LED's? If the resistors are put directly across the 12V cause the LED's not to work and the resistors to release the Lucas smoke we all try so hard to keep inside the wires? If you change the flasher unit you will most likely loose the trailer indicator light on the dash, this may not worry you, but i like to know the trailer lights are working on mine. One way around the problem you have is to fit an extra set of indicators on the bull bar etc. Inc should know a way around this, he sells them.

I think slug_burner's right - "in parallel" is across the 12V ( i.e. in parallel with the LED light pack) and will increase the current drain slightly, therefore making it look like a conventional bulb to the flasher unit. You could also just put a conventional bulb ( which is also a resistor in essence ) in parallel.
However all this defeats one of the main reasons for going to LEDs in the first place. ( i.e. decreasing current draw on the battery )
If you can get a flasher unit that will work properly with the LEDs that'd be the way to go. These are electronic so should last longer ( in theory ). You can then replace any of your other indicator bulbs with LED ones if you want.
Maybe start here http://www.ledshoponline.com/electro...asher_cans.htm

Thanks for the replies. Lamps in the bull bar sounds like the fix for me as I'm fitting one ex a pranged fender once I have finished the tray.
Cheers

Originally Posted by jimbo110

If you change the flasher unit you will most likely loose the trailer indicator light on the dash, this may not worry you, but i like to know the trailer lights are working on mine.

On a side note, could you explain how this is supposed to work. Mine flashes with the indicators, regardless of a trailer. If you have a trailer with a flasher that doesn't work ... what happens?

Ta

Originally Posted by Rosco

On a side note, could you explain how this is supposed to work. Mine flashes with the indicators, regardless of a trailer. If you have a trailer with a flasher that doesn't work ... what happens?

Ta

The standard setup allows for 2X21W bulbs when you turn on the indicators, and in this case, the trailer icon shouldn't keep flashing with the indicator one.

You have probably got a bullbar with it's own indicator bulbs connected in parallel with the standard ones on the car, and this is why the trailer icon is working - it sees the increased load of the bullbar indicator lights as trailer ones.

You can stop this happening by using LED bulbs in the bullbar, or connecting the bullbar lights via a relay, to reduce the load on the flasher unit. This will allow the warning lights to operate correctly with your trailer, and give you proper warning of bulb failure.

Cheers,

Lionel

Yes folks in order to increase the current draw you must parrallel the additional load.

The main benefit that you get from LEDs is an increase in reliability as the LED is not subject to damage by vibration unlike a globe that has a current through the filament and can brake when bumped. The reduced current draw is only an advantage for new vehicle designers that can use lighter wires to make the harness for the LEDs. In a vehicle that was designed to run globes the harness was made with the heavier gauge of wire already so not cost benefits there.

Yes less draw from the electrical system is preferred but and amp or two is not that significant.

Instead of parralleling up a resistor or bunch of resistor buy yourself some more LED lights and hook them up in parrallel. More redundancy and you'll cure your flasher can problem. If you have a multimeter set it to measure amps, place it in series with the LED light pack and see how much current it draws. I would expect a couple of hundred milliamps (500 milliamps = 1/2 amp, which should be about what you would get for 25 LED pack (probably come in 24 LED pack). So if that was the case and your flasher can wants to see 1.5 amps per light then hook up another two LED packs per conner and you will be back to your 1.5 amp draw per corner and your trailer indicator on your dash will work once again.