LED bulbs for rear lights, blinkers, etc

[H4wkeye]

Just curious, did anyone try fitting LED bulbs on the C5 X7 for blinkers, rear positions, stop lights etc? Are there any issues? A friend recently changed his and gotta say it looks really good. But not sure what bulbs he got and if it has to be CANBUS or not?

[MattBLancs]

Not rear lights (and so not really answering your question at all, sorry!) But I've got some in my sidelights at the front. Seems to work well and nice and bright. Sideways firing type, so illumination not directed forward.

They do a weird little flash when you unlock the car which was a surprise!

Obviously they make the old fashioned filament bulbs (headlamps) look all the more orange. But I just don't care.

Am looking at a pair of amber LED replacements for the front indicators (as has the stupid HP24W rather than normal PY21W for no sensible reason) but at little concerned I'll pick up a manic flash speed due to the reduced load.

https://www.ebay.co.uk/itm/402213933113
These are what I am considering

[H4wkeye]

Yeah friend installed some front blinker LEDs off Aliexpress and he said the blinkers were going super fast! Is that due to incorrect load? Maybe GiveMeABreak will know more if he reads the thread

[myglaren]

I had some as front sidelights. They were very cheap and very blue but lasted ages where the tungsten bulbs lasted only weeks, passed the MOT and were never actually used, only ever drove with dipped headlights.

I have LED reversing lights on the Civic that are very bright, came with 50W ally resistors but they weren't needed. Probably would in a canbus system though.

[H4wkeye]

Is the C5 X7 Canbus or not?

[MattBLancs]

Yeah friend installed some front blinker LEDs off Aliexpress and he said the blinkers were going super fast! Is that due to incorrect load? Maybe GiveMeABreak will know more if he reads the thread

Yes, most indicator circuits need the load of the (normal incandescent) bulbs to flash at the right speed.

Bulb gone or tiny load LED bulbs both tends to give very fast flashing.

Swapped to LED T10 bulbs in the Coupe's side repeaters but normal 21W in front and rear. The loss of the load from the (10W) T10's not significant enough to change the flash speed significantly thankfully.

[H4wkeye]

That is interesting to know, thanks! I wouldn't touch my blinkers yet, just the rear P21/5W and the R5W. On the front I have bi-xenons which are Philips 6000K. The side lights are halogen though.

[moizeau]

If the blinkers blink fast add a resistor. It happens on bikes with the mini indicators that have a lower wattage

[H4wkeye]

What about the heat? Do the LEDs get too hot or something? Mainly for the ones that are always on at certain times, like rear positions/stop lights.

[moizeau]

no nothing to with heat, although you may need to place the resistor somewhere aerated. It's because LED's use far less power.

[MattBLancs]

What about the heat? Do the LEDs get too hot or something? Mainly for the ones that are always on at certain times, like rear positions/stop lights.

It's funny, but it's the opposite really - LEDs produce very little heat, but need to keep cool to have a long life.

That's why you see such massive heat sink fins on powerful LEDs - not because they get very hot, but because it is difficult to reject heat to the air with only a small temperature difference between LED temperature and air temperature. But if the little but of heat energy they generate was allowed to build up then the LED would reach a temperature at which it begins to damage itself.

A quick Google (to find a good picture of the fins) has shown it's moved on a stage : these have built in fans to force air cool the heat sink!
https://diversionstores.co.uk/products/ ... 5-hb4-9006


(Shame not road legal )

[H4wkeye]

Ah I see. I may try to switch the rear ones soon. What would happen if I put rear blinkers as LEDs and keep the front halogen for now? They'd flash faster?

[MattBLancs]

Ah I see. I may try to switch the rear ones soon. What would happen if I put rear blinkers as LEDs and keep the front halogen for now? They'd flash faster?

Yes, the load the flasher circuit sees is
front + side repeater + rear bulb
Normally:
24W + 5W + 21W = 50W

Note: just looked it up, side repeaters, T10 = 5 W (not 10W as I stated earlier)

So your rears at 21W aren't far off half the total load. So would expect a significant increase in flashing speed if swapped to much lower power consumption LED equivalents. Suppose as a test, uncouple the rear bulbs and see how fast the front ones go, will be something approaching that with an LED in the rear.

Think I've talked myself out of changing the fronts for same reasoning!

[H4wkeye]

Haha, I totally understand ya! Seems like I won't be touching that for now as well. A friend is currently experimenting with it on his C5 X7 so we'll see how he goes.

[myglaren]

There are canbus compatible LEDs.
These claim to be anyway, sure to be others.