I am sure I have seen a post on this in the past, but can't find it. I fitted LED lights to the interior of the car. They work great, but I have recently noticed something strange. When they go off, either with me sitting in the car, or after I have locked the car up, there is the slightest flicker of light from each bulb. If you stay in the car and  then start the engine, they do go off completely. Once I lock the car in the dark, if you get low down alongside the car, you can see the faintest glow from each LED bulb. As I use the car every day, the battery does not mind this very small light source staying on. I just wondered If say I go on holiday for 2 weeks, it may deplete the battery. Where is the electric coming from to keep these bulbs very slightly glowing when they should be completely switched off. When I put the old standard bulbs back in, it does not do it. Any Knowledgeable  members on here know what is going on? 

It's due to the leds themselves. It's hard to explain, but it's due to the resistance of the leds compared to the halogen bulbs they replace. If you added a resistor (if I remember) across the led and not in series, they wouldn't light up.

 

Some leds have a resistor built into them to avoid this phenomenon. 

Edited 5 August, 20196 yr by tunedude

3 minutes ago, tunedude said:

It's due to the leds themselves. It's hard to explain, due it's due to the resistance of the leds compared to the halogen bulbs they replace. If you added a resistor (if I remember) across the led and not in series, they wouldn't light up.

 

Some leds have a resistor built into them to avoid this phenomenon. 

So maybe I need better quality LED bulbs to avoid this. It's just very odd, as the lights are meant to turn fully off, so where is the electric coming from for that very faint glow?? Any idea tunedude where I can get LED bulbs that don't do this? These ones I got off ebay.

It's more a case of the circuit is designed to be used with halogen bulbs and when you use the led's, the 'charge' in the system doesn't get fully used. I remember seeing something a while back saying word to that effect and to overcome it, it was suggested to use a resistor or a standard halogen bulb somewhere in the circuit.

 

That's one of the thing so called 'canbus friendly' bulbs do is to trick the car into thinking it's a standard bulb because the current flow is the same from the resistor which is built into them.

 

There's no guarantee that putting one of those type of bulbs will work. I put the same led bulbs I've got in my interior, boot and sidelights into my motorbike, and despite being labelled as 'canbus friendly', my bike through a wobbler and produced an error message.

 

If you do wish to keep the white light look in your interior, I'd advise paying that bit extra and avoid led lights, by buying a xenon look bulb. I got Osram cool intense bulbs for my bike and they look spot on.

 

The bulbs which I got for my interior (SMD 501 LED bulbs) don't flash, however you do need to bend the mounting brackets for the light as the light part is a bit bigger than the standard 501 size.

Thanks for the reply tunedude, I will look into those bulbs.

I have just checked the LED bulbs I bought and fitted. They are the SMD LED 501 T10 W5W bulbs. Just tried something else. Took the rear interior bulbs out and put the standard ones back in. At the front, left the LED bulbs in situ. I now no longer have that faint glow from the front ones when they turn off. Odd, very odd. I wish I understood electronics!

I have just ordered some better quality SMD LED 501 T10 W5W  bulbs. Lest see if these work without fault.

 

35 minutes ago, roaddetective said:

I have just checked the LED bulbs I bought and fitted. They are the SMD LED 501 T10 W5W bulbs. Just tried something else. Took the rear interior bulbs out and put the standard ones back in. At the front, left the LED bulbs in situ. I now no longer have that faint glow from the front ones when they turn off. Odd, very odd. I wish I understood electronics!

Seems logical to me. If as "tunedude" says there is a "charge" in the circuit, then the original bulbs are using up that charge, so depleting it.  i expect if you waited long enough the led bulbs would eventually go out.  

Just now, ords said:

Seems logical to me. If as "tunedude" says there is a "charge" in the circuit, then the original bulbs are using up that charge, so depleting it.  i expect if you waited long enough the led bulbs would eventually go out.  

You could be right, but not sure how long. Last night I was having a fiddle with them and then left them alone.They were still gently glowing 3 hours later. I guess if it is a charge in the circuit that is the cause, it is not slowly depleting the battery power. Lets see what the new LED bulbs do when they arrive.

Like I say, by getting different bulbs it may sort said problem out. I stress may.

it's about design, current requirements and how the system sees that doors are open. 

 

My take on this: a halogen bulb is slow. It's also a specific resistance. So a 12V/5W bulb has a resistance of around 2.5 ohms. Go look up Ohm's law for this one. 

As I understand it, the way the system works is it pushes a low level of current through the door switch circuits on a regular basis and when these switches open (because the doors are), then the lights are triggered. This current is low enough and fast enough - short spikes sent multiple times a second - that a halogen bulb can't react fast enough. But an LED with a crappy driver (or none) will, so it either glows or flashes (which is what happens on my A2). The example there is simple: I have two LEDs in the hatch. When there's no halogen boot light in place, the hatch LEDs flash all the time when the engine is running and for another 30 seconds after the car is locked. It's because they're using simple MR16 drivers from Aliexpress. If I replace the standard boot bulb, the flashing stops. Ergo: no load and I get flashing. I've tried a couple of solutions involving diodes and fat capacitors with a circuit from an electrical engineer, and no dice so far but I need to follow this up.

 

Good quality LEDs will have a dummy load of some variety to stop both the flashing and low-level current use. It'll be a very small current as the LEDs are a *lot* more sensitive to current than halogen bulbs, but it still needs to have a load somewhere, as you're asking a circuit to do something it wasn't designed for, namely provide about a third of the current and still work correctly. 12V 5W uses maybe 0.5A, a 150mA LED would be similar in light output.

Just dropping a 3-5Ohm 5W resistor across the LED may work but doesn't resolve the problem and could cause bigger problems. Quality LED bulbs are the answer: Philips may have some, Osram do, and companies like hypercolor spend time making sure their drivers a) work and b) don't create interference.

 

 - Bret

6 hours ago, brettikivi said:

it's about design, current requirements and how the system sees that doors are open. 

 

My take on this: a halogen bulb is slow. It's also a specific resistance. So a 12V/5W bulb has a resistance of around 2.5 ohms. Go look up Ohm's law for this one. 

As I understand it, the way the system works is it pushes a low level of current through the door switch circuits on a regular basis and when these switches open (because the doors are), then the lights are triggered. This current is low enough and fast enough - short spikes sent multiple times a second - that a halogen bulb can't react fast enough. But an LED with a crappy driver (or none) will, so it either glows or flashes (which is what happens on my A2). The example there is simple: I have two LEDs in the hatch. When there's no halogen boot light in place, the hatch LEDs flash all the time when the engine is running and for another 30 seconds after the car is locked. It's because they're using simple MR16 drivers from Aliexpress. If I replace the standard boot bulb, the flashing stops. Ergo: no load and I get flashing. I've tried a couple of solutions involving diodes and fat capacitors with a circuit from an electrical engineer, and no dice so far but I need to follow this up.

 

Good quality LEDs will have a dummy load of some variety to stop both the flashing and low-level current use. It'll be a very small current as the LEDs are a *lot* more sensitive to current than halogen bulbs, but it still needs to have a load somewhere, as you're asking a circuit to do something it wasn't designed for, namely provide about a third of the current and still work correctly. 12V 5W uses maybe 0.5A, a 150mA LED would be similar in light output.

Just dropping a 3-5Ohm 5W resistor across the LED may work but doesn't resolve the problem and could cause bigger problems. Quality LED bulbs are the answer: Philips may have some, Osram do, and companies like hypercolor spend time making sure their drivers a) work and b) don't create interference.

 

 - Bret

Blimey, a lot of that was way over my head. Hopefully though, the ones I have ordered will sort out the problem. If not, I will look at the Osram ones you suggest. Thank's though for that very informative answer brettikivi. 

Just fitted 5 of the new LED bulbs I bought via ebay into the interior of the car. At last, not a flicker of light once you turn them off. It just needed a little bit more investment from me on better quality bulbs. I bought 8 bulbs and the total price was £15.44, not too bad. If anyone wants to know the make of LED bulb I bought, they are AUXITO 12v LED Chip 3014. They fit socket- 168, 194, 2825, T10, W5W. They would not quite fit fully into the two boot light sockets, as they are for some reason, a fraction too tight to the sides. The other LED bulbs fit okay in there  anyway and don't shed any flicker of light when they are turned off.