Author Topic: ARC correction for LED lights?  (Read 2323 times)

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GTVeloce

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ARC correction for LED lights?
« on: July 16, 2021, 12:56:09 PM »
Has anyone managed to correct the ARC when it thinks a bulb is down due to LED lights? I want to mention my ARC is working correctly - no Christmas tree lights going on. I installed LED lights almost everywhere (except headlights) which are so much better than the originals but of course the ARC thinks I am down a bulb. I know I could correct it by installing a resistor next to every light but that is a lot of resistors! I'm hoping I could install fewer resistors by installing them on the input to the ARC instead.

Has anyone managed to do this?

Craig_m67

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Re: ARC correction for LED lights?
« Reply #1 on: July 16, 2021, 03:35:52 PM »
Remove ARC lamp/led from dash… you’re effectively negating it anyway
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GTVeloce

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Re: ARC correction for LED lights?
« Reply #2 on: July 19, 2021, 10:21:44 AM »
Remove ARC lamp/led from dash… you’re effectively negating it anyway
A possibility but not my preferred course of action. The ARC does work in every other way and I believe if I get the resistor values correct I could still have the ARC working for lights i.e. a bulb failure will illuminate the ARC.

I'm confident I could do it if I placed a resistor on every light but that is 12 resistors (by my quick calculation) that I need to splice into the wiring loom. Given I am not sure yet of the value required (I plan to install a pot first and the determine the value from that) it's a lot of stuffing around. If only I could splice into the ARC instead - one connection instead of 12.

This also raises another issue and whether the combination of 12 resistors in one would generate too much heat given the location of the ARC? I'd prefer not to burn the car down just to fix a few flashing lights...

Colin Edwards

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Re: ARC correction for LED lights?
« Reply #3 on: July 19, 2021, 11:33:55 AM »
Looked into this myself for a while as I've also replaced a few incandescent globes with LED's on my 75.  I suspect the ARC looks for what will effectively be a dead short across the globe sensing input.  A cold filament will feature an extremely low resistance until it heats up / glows white hot.
 
A say 6W globe will rapidly increase in resistance from near 0 ohms when cold to 24 ohms when hot / at full brightness. 
To stooge the ARC into "thinking" all globes are intact will require very low value resistors at each globe.  If say that resistance is as low as 2.2 ohm, we need a 65watt resistor!!  With 12 of these scattered about the car, total wattage needed is 785W!!  We would be consuming and wasting more power than we save by installing LED's in the first place.  Not to mention the heat created.
Better to locate the discrete input to the ARC at the ARC itself.  Its probably one of the 2w carbon resistors on the N22 pcb.  I've tried to trace this out more than once, however the schematic and what's on the car don't seem to add up!!!  Its still on the "to do" list.

Present
2020 Giulietta Veloce
2018 Abarth 124 Spider
1987 75 3.0

Past
2015 Giulietta QV
2009 159 3.2 Ti Q4
2012 Giulietta TCT Veloce
2006 147 Ti 2 door Selespeed
1979 Alfasud Ti 1.5

GTVeloce

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Re: ARC correction for LED lights?
« Reply #4 on: July 22, 2021, 10:15:41 AM »
Thanks Colin. Yes, like you, I have tried a few times at the ARC but the schematic isn't accurate and not quite as comprehensive as I would like. If I had a spare ARC I would open it up and experiment on that but I don't. Hence I was hoping I could piggyback off someone else's hard work  ;D

Looks like I am going to have to do the hard work  ::)

shiny_car

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Re: ARC correction for LED lights?
« Reply #5 on: July 22, 2021, 12:03:42 PM »
Very happy for you to do the hard work  ;D .

I'll be quite interested to hear of any success, as I want to fit LEDs for indicators and brake lights, depending upon how bright they look.

I don't have electronics skills, just general auto electrical skills.
Good luck!
Giulietta QV TCT . 1.75 TBi . Magnesio Grey - Black
GT . 3.2 V6 . Q2 . Kyalami Black - Red
75 . 3.0 V6 . Alfa Red - Grey

GTVeloce

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Re: ARC correction for LED lights?
« Reply #6 on: July 26, 2021, 11:34:33 AM »
Looks like I'm going to have to roll up my sleeves!  ;D

I've put LED indicators (along with an electronic flasher unit) and they are much brighter than original. Highly recommend it. I've also replaced front park lights, rear park, stop, reverse, rear fog, number plate, boot, bonnet, dash, overhead dome, glovebox, clock, cigar lighters, ash tray...have I missed anything?! The only bulbs I've not replaced with LED are headlights (provided you upgrade the wiring and add relays they are fine) and the front fogs. Contemplated turning the front fogs into LED driving lights and hard wiring them to the ignition to run as DRL but haven't made it that far yet.

bteoh

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Re: ARC correction for LED lights?
« Reply #7 on: July 26, 2021, 05:35:23 PM »
Would be interested in LED lights for the indicators and would like brighter lights esp in the rear as they are woefully dim when flashing. Let us know what you used and where to source them from?
Thanks :)

GTVeloce

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Re: ARC correction for LED lights?
« Reply #8 on: July 26, 2021, 08:59:16 PM »
I have bought most of my bulbs (including the indicators) from here;
https://www.ledshoponline.com.au/shop/
I have tried to buy the brightest bulb possible so if they have a BA15S Hi-Power version that's the one I have gone for.

I have also bought a few of the internal bulbs from a random ebay store and some from Stedi.

I have also changed all my bulbs except the indicators on my Alfetta GTV and am very happy with the result. I have bought the indicators but haven't got around to changing them yet as there is a little fiddling required to get the flasher unit to work. I had to do the same with the 75 but the indicators in that are far worse on a 75 than a GTV.

Colin Edwards

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Re: ARC correction for LED lights?
« Reply #9 on: July 27, 2021, 09:46:24 AM »
+1 for ledshoponline.com.au

Replaced all parking globes, indicator globes, interior globes in headlining and rear numberplate illumination globes.
Present
2020 Giulietta Veloce
2018 Abarth 124 Spider
1987 75 3.0

Past
2015 Giulietta QV
2009 159 3.2 Ti Q4
2012 Giulietta TCT Veloce
2006 147 Ti 2 door Selespeed
1979 Alfasud Ti 1.5

bteoh

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Re: ARC correction for LED lights?
« Reply #10 on: July 27, 2021, 03:43:16 PM »
Thanks guys.
Anyone tried this company :-  https://www.eslights.com.au/

They claim that these are the brightest on the market :-  https://www.eslights.com.au/product-page/2x-2021-xstorm-1156-ba15s-canbus-inicator-turn-signal-led-bulbs

Colin Edwards

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Re: ARC correction for LED lights?
« Reply #11 on: July 27, 2021, 05:02:02 PM »
Before spending a heap of folding on LED's, need to remember the alternator is the final source of power to drive the lights.
 
The process of engineering a right hand drive version of a largely left hand drive car meant the RHD 75 wiring loom is a modified LHD wiring loom.  End result is additional connections and cables in the circuit from the alternator to the fuse panel.  Although a fair bit of work (ask me why I know!), simplifying the circuit and replacing with cable 3 x times the cross section of the existing makes a huge different to the voltage ultimately fed to all the 75 electrics including the lights.  This cable also needs to be as short as practically possible.  Its critical the cable from the alternator to the fuse box is capable of conducting the required current with minimal voltage drop.  Its the voltage drop between the alternator and the fuses that dulls the lights.

Also need to ensure the alternator is up to the task.  Most club sponsors should be able to lay their hands on replacement regulator / rectifier assembly for the alternator.  These are usually supplied with new brushes.  As long as the bearings are ok, the alternator should be ok for another 150,000klm!
Don't polish the alternator slip rings with ANY abrasive.  The slip ring surface should be a similar colour to the surface of the carbon brush - if it is its in perfect condition. 
« Last Edit: July 27, 2021, 05:08:43 PM by Colin Edwards »
Present
2020 Giulietta Veloce
2018 Abarth 124 Spider
1987 75 3.0

Past
2015 Giulietta QV
2009 159 3.2 Ti Q4
2012 Giulietta TCT Veloce
2006 147 Ti 2 door Selespeed
1979 Alfasud Ti 1.5

GTVeloce

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Re: ARC correction for LED lights?
« Reply #12 on: July 27, 2021, 08:59:37 PM »
This is my 75 with the led store rear lights and number plate lights. Note, this is not my brake lights (they are even brighter!), just the rear park lights.

GTVeloce

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Re: ARC correction for LED lights?
« Reply #13 on: July 27, 2021, 09:04:01 PM »
And this shows the interior dash lights and the overhead dome light. There is no extra lighting here - this is how bright it is at night with the doors open. You can also see the front park lights reflecting off the fence.

bteoh

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Re: ARC correction for LED lights?
« Reply #14 on: July 27, 2021, 11:56:22 PM »
Wow, that is super nice. Did you get most of the globes from ledshoponline? With the dashboard leds, did you get any problems with the ARC warning lamps? Or indicator BA15s leds?
If no problems, I will do the same as they are cheaper compared to the other store.
Cheers :)