12v AC LEDs

stux99 · 2nd March 2010, 19:40

Just thought I would ask here..
I have some LED downlighters marked 12v AC, I have tried them on car battery and they appear to work fine.
So, battery being DC will I do them or the battery any harm.
Sorry if this is a dippo question but Google could'nt help.

Stu

Jezzer 1 · 2nd March 2010, 19:51

I am guessing these are for household use ie not for a car?

It's very unusual to get any solid-state device such as an LED to run on AC. My guess is there is some additional circuitry in the LED component which rectifies any
AC component and converts it to DC. If you supply it with DC from a battery, this just passes straight through the rectifier as there is no AC component. Don't think you'll do anything any harm

stux99 · 2nd March 2010, 20:11

Yes, domestic downlighters. Thanks for the quick response Jezzer

Next project under way

amableson · 2nd March 2010, 20:36

The majority of led lights do not work off straight dc they work off a pulsed supply, if you have ever been aware of the car in front with led brake lights or nightime running lights.
The reason for this is that an led pulsing will give greater brightness and lower heat. its the heat that reduces the efficiency and the light output.
An led working on ac pulses at 100hz, 2x50hz.
Sorry it's a bit techy but thats how it works.

T-Cut · 2nd March 2010, 21:54

Quote:

Originally Posted by amableson

The majority of led lights do not work off straight dc they work off a pulsed supply

All the LEDs I've had work by simply connecting them across the battery. Where's the pulse in that?

TC

2nd March 2010, 19:40	#1
stux99 Posted a thing or two MG3/TF Spark/ MGTF Steppy/ MG GS Join Date: Dec 2007 Location: Wincanton,Somerset Posts: 1,073 Thanks: 6 Thanked 9 Times in 7 Posts	12v AC LEDs Just thought I would ask here.. I have some LED downlighters marked 12v AC, I have tried them on car battery and they appear to work fine. So, battery being DC will I do them or the battery any harm. Sorry if this is a dippo question but Google could'nt help. Stu __________________ [SIGPIC][/SIGPIC]

2nd March 2010, 19:51	#2
Jezzer 1 I really should get out more....... 75 V8 Connoisseur SE Saloon: 75 V8 Contemporary SE Saloon and others!!! Join Date: Feb 2009 Location: Warwick Posts: 2,320 Thanks: 1 Thanked 180 Times in 77 Posts	I am guessing these are for household use ie not for a car? It's very unusual to get any solid-state device such as an LED to run on AC. My guess is there is some additional circuitry in the LED component which rectifies any AC component and converts it to DC. If you supply it with DC from a battery, this just passes straight through the rectifier as there is no AC component. Don't think you'll do anything any harm __________________ *Best regards,* *Jeremy.*

2nd March 2010, 20:11	#3
stux99 Posted a thing or two MG3/TF Spark/ MGTF Steppy/ MG GS Join Date: Dec 2007 Location: Wincanton,Somerset Posts: 1,073 Thanks: 6 Thanked 9 Times in 7 Posts	Yes, domestic downlighters. Thanks for the quick response Jezzer Next project under way __________________ [SIGPIC][/SIGPIC]

2nd March 2010, 20:36	#4
amableson Gets stuck in Ex Rover 75 owner Join Date: Nov 2006 Location: Boston, Lincolnshire. Posts: 553 Thanks: 0 Thanked 2 Times in 2 Posts	The majority of led lights do not work off straight dc they work off a pulsed supply, if you have ever been aware of the car in front with led brake lights or nightime running lights. The reason for this is that an led pulsing will give greater brightness and lower heat. its the heat that reduces the efficiency and the light output. An led working on ac pulses at 100hz, 2x50hz. Sorry it's a bit techy but thats how it works. __________________ Regards Andrew.[SIGPIC][/SIGPIC]