Testing an LED bulb?

[Ingwe]

Have two G4 1.5W DC 10-30v bulbs in the overhead light in our van. One bulb kept flickering on and off. It is about a year old (bought from Aten lighting) and has worked fine till now as the other. I have replacements but wondered how to test such a bulb with a digital meter.
I tested for continuity by touching the probes against the two wire contacts sticking out the bottom of the bulb but there was no beep from the meter. I tested all the spares and no beep so doubt this is a way of testing such bulbs. Is there a way to test such bulbs?
Unlike conventional candescent bulbs where you can see the filament there seems to be no way to physically see whether the led bulb is duff.

 

[Richard n Ann]

The bulbs are faulty, probably a resistor going open when it heats up.
The fact they are on and flickering is the test, they would probably look OK on a diode test.

 

[treblid]

. I have replacements but wondered how to test such a bulb with a digital meter.

You can't really. It's easier to use a 12V power supply or battery to test them.
As said already, they are faulty. Flickering is a common failure mode especially for cheap lamps.

 

[Stealaway]

Have two G4 1.5W DC 10-30v bulbs in the overhead light in our van. One bulb kept flickering on and off. It is about a year old (bought from Aten lighting) and has worked fine till now as the other. I have replacements but wondered how to test such a bulb with a digital meter.
I tested for continuity by touching the probes against the two wire contacts sticking out the bottom of the bulb but there was no beep from the meter. I tested all the spares and no beep so doubt this is a way of testing such bulbs. Is there a way to test such bulbs?
Unlike conventional candescent bulbs where you can see the filament there seems to be no way to physically see whether the led bulb is duff.

It will be faulty but they are so cheap to replace

G4 1.5W - 12v DC LED Light Bulb to Replace 15W Halogen Bulbs - UK Stock | eBay

High luminance. Socket Type: G4. Colour: Warm white/Cool white. Colour Temperature: 3000K/6000K. Lighting Angle: 360. Easy to install.

www.ebay.co.uk

 

[Richard n Ann]

It will be faulty but they are so cheap to replace

G4 1.5W - 12v DC LED Light Bulb to Replace 15W Halogen Bulbs - UK Stock | eBay

High luminance. Socket Type: G4. Colour: Warm white/Cool white. Colour Temperature: 3000K/6000K. Lighting Angle: 360. Easy to install.

www.ebay.co.uk

There's no voltage regulator on these though so watch they don't get hot when the charger is on.

^{_{Subscribers  do not see these advertisements}}

 

[L' Hobo]

The way I understand it is, it's not a bulb, it's a light emitting diode. LED.
It might be better to Google, how does one test a Diode?

 

[Richard n Ann]

The way I understand it is, it's not a bulb, it's a light emitting diode. LED.
It might be better to Google, how does one test a Diode?

If the bulb was a simple diode it can be tested with the diode test setting on a multimeter, if they are OK you get a reading of aboit 0.5 volts and if it's a light Emitting variety it also lights up slightly.

Problem with these bulbs though is there is a voltage regulator circuit running the diodes, about 6 of them. They are too tiny to mess about with... Bin them

 

[Vaman]

You can test an LED with the Diode test function on most modern multi-meters, It will conduct (provide a voltage reading, often around 0.6V) in one direction but not in the other direction. Just swap the black and red probes at the LED to test. The LED would often glow ( if it was a standard small )LED as the Diode check will be enough voltage to make glow. However a vehicle LED will require too much current so do not expect it to glow, the standard Diode (the symbol is a cross with a triangle on the meter) test may however still be valid.

Also make sure you connect the bulb the correct way round if using a battery or other power supply to test it, reverse voltage may well blow the LED.
HTH

 

[Captain Yoghurtpot]

This is a very apt thread.
I have been having problems with 2 led lamps which are for an outside fitting at home on 240v.
Upto last year the replacement lamps lasted ages.
Then they wore out ( 6yrs old) so bought some replacement ones.
Lasted about a week.
Bought some more, and the same.
It would seem that the quality of said lamps is not what it used to be, and have purchased such from many outlets, and not expensive but not neccisarily of well known brands.
Think it is time to visit a more reputable supplier as it would appear that within the budget end of this market, Quality of manufacture and longevity is a non-starter.
PS: Have checked the actual light fitting and wiring, and all is fine.

 

[Lenny HB]

You can test a standard single LED diode but you can't test a LED lamp of the type we use in Motorhomes as they have an electronic voltage regulator chip before the LEDs. You could test the individual LED chips if you know what you are doing but it won't help LEDs rarely ever fail it's the voltage regulator that fails.

^{_{Subscribers  do not see these advertisements}}

 

[DavidG58]

Simplest test plug tge flashing in to the fitting with the working bulb, if it still flickers bin it

 

[Ingwe]

It will be faulty but they are so cheap to replace

G4 1.5W - 12v DC LED Light Bulb to Replace 15W Halogen Bulbs - UK Stock | eBay

High luminance. Socket Type: G4. Colour: Warm white/Cool white. Colour Temperature: 3000K/6000K. Lighting Angle: 360. Easy to install.

www.ebay.co.uk

Thanks for the ebay link. I pay more to get the bulbs from Atem lighting as they apparently supply a better quality product, in all probability also made in China, as are most things these days.Yes, I appreciate the bulbs are faulty and yes, in the scheme of things, they are cheap to replace.