Boot light maximum power in Citroen Grand C4 Spacetourer

[Finalgrab]

Hi there,
in my Citroen Grand C4 Spacetourer from 2022 I am trying to connect additional LED strip to the small boot light in the luggage space (I think I have the PA6-MX30). Unfortunately the light just blinks and turns off.
Is there any maximum power this light can consume? (My assumption is that the LED strip takes to much power)
Any ideas what is happening behind this.

Thank you

[mickthemaverick]

LED strips are polarity sensitive, are you sure you have it connected the right way round?

[Finalgrab]

LED strips are polarity sensitive, are you sure you have it connected the right way round?

Yes, I am. In one way it does not works at all. In the second way it works as described. Unfortunately I don't have enough strong multimeter to measure the current, so I don't know the total power of the strip right now. That's why I'm asking.

[mickthemaverick]

OK. My assumption is that being a modern car the lighting is possibly ECU controlled. If the ECU detects an abnormal current draw it may cut off the supply to the light concerned.
A suggestion which may or may not work:
If you wire in a relay coil to the supply and then connect both the original bulb and the LED via the contacts to a seperate 5A fuse you may have some success as long as the relay coil mimmicks the original bulb's resistance.

Something like this rough sketch:

MTMO

[myglaren]

Or perhaps a resistor. I bought LEDs for the reversing lights and they came with resistors for canbus systems. Not needed on the Civic.

[Finalgrab]

Or perhaps a resistor. I bought LEDs for the reversing lights and they came with resistors for canbus systems. Not needed on the Civic.

It's true that other seller's strips do have some little box on the input wire and mine has nothing. Do you have any tip how to find, how strong resistor shell I use?

Thanks

[mickthemaverick]

This site has the info for the resistor method. https://www.electronics-tutorials.ws/re ... istor.html

[myglaren]

These are the ones that came with my LEDs. Never used though.

50 Watt 6 Ohm.

[wheeler]

Have you confirmed its not a faulty unit by trying it directly on the battery? Does it work ok if you do this?

[Finalgrab]

Have you confirmed its not a faulty unit by trying it directly on the battery? Does it work ok if you do this?

The battery is new in the car, the original boot light works correctly and the led strip works perfectly when I connect it to some power source at home.

[myglaren]

Have you confirmed its not a faulty unit by trying it directly on the battery? Does it work ok if you do this?

The battery is new in the car, the original boot light works correctly and the led strip works perfectly when I connect it to some power source at home.

Which more or less confirms the need for a load resistor. Worth a try anyway.

[Finalgrab]

Dear all,
thank you for your kind help. Finally I've had better multimeter.

At the end it was totally not about a resistor. I've gone through some discussions and the resistor is being used for same size lightning where usually the LED light is more bright but consumes very low electricity and the car system does not detects the consumption.

In my case, current light is 5W bulb and the light strip in 4m was around 20W. The flashing of the strip before it was shut down was that systems turned the strip on, detected too high consumption and turned it off. This all around 5 times and it disabled the light (for about 30 minutes).
The resolution was very simple: I was cutting pieces of the strip off until it stopped blinking and started working. Now I have about 2,5m, that means around 12W and it works.

I am not sure if there is any solution to have the whole 4m strip (to cover the whole circuit of luggage space entrance) with same strip - maybe to find some strip with less diods or lower consumption, but that's something usually not mentioned in the offers.

[PaulC5]

20w LED must be bright, are you trying to light up the road or a garage and not just the boot ? Torches are only about 1w and light up well. Ceiling light LEDs are only 5w.