Warning Lamp Cluster

[StagJonno]

Just saw the "bettercarlighting" ad in the StagMag. They suggest buying their kit of 8 LED replacements to get better indications which, on the face of it seems a "bright" idea. I think they are misguided.

I know many already are aware that the Ignition lamp needs to be a filament type as it forms part of the alternator excitation circuit. However, my experience is that only the Direction Indicators and High Beam warning lights can be substituted with LEDs (done this with another make and can recommend them). All the others don't seem to work on mine, which I'm pretty sure is because the polarity of the bulb holders is reversed (LEDs being polarity sensitive). I've not yet fully investigated so others may have a view (it's just possible I didn't seat the odd one properly).

I've written to the company to flag this issue up, but hoped to assist others being too blinded by the ad (pun intended). They do have other stuff on their website which is worth a look ( www.bettercarlighting.co.uk )

Jonno

[TR5convalescent]

Jonny, I am slightly confused. Do you mean the polarity is reversed on your car or do you mean that this is standard?

[StagJonno]

I've only got experience of my car, but I believe it to be standard wiring and the way the warning cluster printed circuit board is configured.

I got what I wanted, which was improved brightness for the turn indicators as it's too easy to miss that the self-cancelling hasn't happened, especially with the hood down.

Jonno

[TR5convalescent]

Thanks, Jonno. I guess the answer is to buy the individual LEDs.

[Pete]

I know many already are aware that the Ignition lamp needs to be a filament type as it forms part of the alternator excitation circuit. However, my experience is that only the Direction Indicators and High Beam warning lights can be substituted with LEDs (done this with another make and can recommend them). All the others don't seem to work on mine, which I'm pretty sure is because the polarity of the bulb holders is reversed (LEDs being polarity sensitive).
Jonno

LEDs will only pass current one way as they are diodes. I would have thought if connected the correct way, then they would not interfere with the alternator excitation circuit.

[milothedog]

LEDs will only pass current one way as they are diodes. I would have thought if connected the correct way, then they would not interfere with the alternator excitation circuit.

Sometimes they don't work (not suitable) in some circuits because they don't have the resistance a bulb would have this can be overcome by soldering a small resistor across it. We had to do this with instrument clusters at work.

Ian

[StagJonno]

LEDs are limited to a slack handful of milliamps, and typically will have a series resistor of ~600 ohms for a 12V system. I think the alternator needs something in the order of 100 - 200 ohms, hence the additional external, parallel resistor Milo mentions.

Had an email back from bettercarlighting and this is their solution, too. They'll include a resistor in the bundle for free. They're disputing my assessment, saying that they developed these for some Stag owners and not had any complaints (maybe they've not yet fitted them?). Anyway, they're sending a couple of samples for me to enjoy, so I'll update IDC.

Jonno

PS - just openened up a spare cluster which confirms my recollection the "rings" for indicators and High Beam are all commoned, with a separate commoning for those signals where the switching is to earth (ie Oil, Choke, H'brake & Fuel), so the chances of them working without swapping the internal bulb connections isn't good!

Jonno