ALTERNATOR EXCITER WIRE
Discussion
Hi all.
I am working on a tarmac spec rally car, fitting engine management and loom plus a bespoke wiring loom, and as it has acewell digi dash there is no provisions for the battery warning light,, Now normally the average person doesn't think to much about the alternator apart from the dash warning light coming on,,
Here is my problem no dash warning light to connect to as no original dash unit,, So i ran a wire from the flick type ignition switch as using press button start, to a test bulb approx 12v 5w, and ignition on 12.7v at the battery, the bulb is on ok, Then fire up the engine it went off for a few seconds then came back on,,
Restarted the engine still on, if you rev it up it makes no difference,, i tried a higher wattage bulb still the same,, When the engine is cranking the bulb is off,,
it seems the alternator and battery voltage do not match so the light comes back on,, The engine had been sat for approx 3 years,, so it maybe a alternator fault i also noticed when the engine is running for the first few minutes there is a strange noise then it disappear's,, i pretty sure it is from the alternator,, any views on this would be welcome as i am coming to the end of the road on this apart from getting the alternator checke
I am working on a tarmac spec rally car, fitting engine management and loom plus a bespoke wiring loom, and as it has acewell digi dash there is no provisions for the battery warning light,, Now normally the average person doesn't think to much about the alternator apart from the dash warning light coming on,,
Here is my problem no dash warning light to connect to as no original dash unit,, So i ran a wire from the flick type ignition switch as using press button start, to a test bulb approx 12v 5w, and ignition on 12.7v at the battery, the bulb is on ok, Then fire up the engine it went off for a few seconds then came back on,,
Restarted the engine still on, if you rev it up it makes no difference,, i tried a higher wattage bulb still the same,, When the engine is cranking the bulb is off,,
it seems the alternator and battery voltage do not match so the light comes back on,, The engine had been sat for approx 3 years,, so it maybe a alternator fault i also noticed when the engine is running for the first few minutes there is a strange noise then it disappear's,, i pretty sure it is from the alternator,, any views on this would be welcome as i am coming to the end of the road on this apart from getting the alternator checke
Thanks for the reply,, The alternator only has two connections one is the heavey battery one, and the other is the exciter wire i have fed my own connection from the ignition flick switch to a bulb in series to the alternator exciter wire,, so no other wires in the system,, i had a good crawl around the underside today to check no other wires,, it should be working as describe,, so hopefully the alternator is faulty unless someone has a better explanation,
Hi
The 12v is from a missle type red case switch which is part of the press button start,, then the bulb is wired from that in series to the exciter wire,, I think the problem is the alternator, as today touched quickly to the battery + which should make the alternator charge battery but nothing,, so having it checked test dont guess,, and i hope that is it,, when the bulb ignition on is to ground, then once running it should equal voltage and the light off
The 12v is from a missle type red case switch which is part of the press button start,, then the bulb is wired from that in series to the exciter wire,, I think the problem is the alternator, as today touched quickly to the battery + which should make the alternator charge battery but nothing,, so having it checked test dont guess,, and i hope that is it,, when the bulb ignition on is to ground, then once running it should equal voltage and the light off
)How is the bulb wired?
One side to 12V from the battery (IGN ON feed) and the other side to the Alternator terminal?
The way it works is with ignition on and alternator not turning the bulb gets 12V from battery and 0V from the alternator so there is a potential difference and the bulb lights up. Start the engine and with a correctly operating alternator producing around 13V-14V there is no potential difference between the alternator and battery via the bulb (12Vish either side) so the light then goes out. If the alternator is faulty and drops the voltage output then there is again a potential difference between alternator and battery and the bulb will begin to light up, the brightness depending on the difference. That is the way the light works on older style alternators, newer ones will differ with ECU control of the light.
If the light is always on the bulb may be wired wrong, you may not have an IGN ON battery 12V feed on the other side of the bulb. Alternatively the alternator could be knackered but you can check the voltage output with it running.
One side to 12V from the battery (IGN ON feed) and the other side to the Alternator terminal?
The way it works is with ignition on and alternator not turning the bulb gets 12V from battery and 0V from the alternator so there is a potential difference and the bulb lights up. Start the engine and with a correctly operating alternator producing around 13V-14V there is no potential difference between the alternator and battery via the bulb (12Vish either side) so the light then goes out. If the alternator is faulty and drops the voltage output then there is again a potential difference between alternator and battery and the bulb will begin to light up, the brightness depending on the difference. That is the way the light works on older style alternators, newer ones will differ with ECU control of the light.
If the light is always on the bulb may be wired wrong, you may not have an IGN ON battery 12V feed on the other side of the bulb. Alternatively the alternator could be knackered but you can check the voltage output with it running.
mroad, Thanks for the reply, you got in one,, the igntion on light to ground then once running the alternator to battery equal voltage light off if a difference light on,, I have not normally thought to much about alternators as most of the time easy to diagnose,, with std original car wiring,, Now this car complete new kit car type loom for a better word is in my head at first wiring fault,, but as i have tried everything it points to the alternator, we did not know the history of it as the car came as a shell and engine basically,
It has a red case type missile sort of flick toggle switch for the ignition which is linked to the press button start,, The feed for the toggle switch comes from the battery 12v+.. i have the test bulb from a terminal at the toggle switch in one side of the bulb then out to the alternator exciter wire,, it is on with toggle switch (ignition ) on, and as you crank the engine it looks like it is off,, and depending on how much voltage the battery has it sometime goes off on starting the engine,, then comes back on,, i also tgried with the engine running touched the battery plus + terminal with the exciter wire which should make the alternator charge the battery,, so i could disregard the test bulb side of the circuit, if it did then charge i know it is the test bulb wiring, but nothing,, so should have a phone call today about the result of test for the alternator,, so i hope it is faulty obvious reason's. 2001 approx year type alternator,
It has a red case type missile sort of flick toggle switch for the ignition which is linked to the press button start,, The feed for the toggle switch comes from the battery 12v+.. i have the test bulb from a terminal at the toggle switch in one side of the bulb then out to the alternator exciter wire,, it is on with toggle switch (ignition ) on, and as you crank the engine it looks like it is off,, and depending on how much voltage the battery has it sometime goes off on starting the engine,, then comes back on,, i also tgried with the engine running touched the battery plus + terminal with the exciter wire which should make the alternator charge the battery,, so i could disregard the test bulb side of the circuit, if it did then charge i know it is the test bulb wiring, but nothing,, so should have a phone call today about the result of test for the alternator,, so i hope it is faulty obvious reason's. 2001 approx year type alternator,
Anyone try running their own exciter wire to the alternator with an inline diode? https://www.youtube.com/watch?v=e9knTSJA1eo&t=...
kar-ander said:
Anyone try running their own exciter wire to the alternator with an inline diode? https://www.youtube.com/watch?v=e9knTSJA1eo&t=...
The person that did this is full of b
ks, he could have fixed the fault quicker than carrying out that bodgeI find it hilarious that he chose to wire in a diode rather than a resistor or a seperate 3 to 5 watt bulb
Thanks for posting, it was a f
king howl watching that videoHi All.
Been a long time since this fault was posted,, But in fact I put in a Diode in line and it fixed the fault, The second car same type except different spec engine, I wired this car from scratch myself inc making the engine loom for the std alone ecu, Everything worked as it should??
so who knows,
Regards SENNNA1
Been a long time since this fault was posted,, But in fact I put in a Diode in line and it fixed the fault, The second car same type except different spec engine, I wired this car from scratch myself inc making the engine loom for the std alone ecu, Everything worked as it should??
so who knows,
Regards SENNNA1
senna1 said:
Hi All.
Been a long time since this fault was posted,, But in fact I put in a Diode in line and it fixed the fault, The second car same type except different spec engine, I wired this car from scratch myself inc making the engine loom for the std alone ecu, Everything worked as it should??
so who knows,
Regards SENNNA1
Yes but what a load of bBeen a long time since this fault was posted,, But in fact I put in a Diode in line and it fixed the fault, The second car same type except different spec engine, I wired this car from scratch myself inc making the engine loom for the std alone ecu, Everything worked as it should??
so who knows,
Regards SENNNA1
kskar-ander said:
Anyone try running their own exciter wire to the alternator with an inline diode? https://www.youtube.com/watch?v=e9knTSJA1eo&t=...
That is a hideous bodge - I can't imagine why somebody who understands the problem well enough to design that bodge doesn't just fix the problem - which could be as simple as a broken wire or blown bulb. It's also poorly executed (unprotected wires running round the engine bay, solid wire diode unsupported in the middle of a cable run, sticky tape for insulation) and a bad example of how to implement under bonnet wiring.senna1 said:
Penelope Stopit said:
Yes but what a load of bks
I think you should get off your high horse tw-t, you don't know the vehicle in question etc, and I'm not here to educate you.kstI don't need to know what vehicle it is
I do know that the above is a load of b
ksAnyway, the method used is very funny and if you followed that method you're very funny
There is no way you could possibly educate me.....If you knew the job inside out you wouldn't have opened this topic asking for help
You're funny in a funny sort of way
Edited by Penelope Stopit on Tuesday 9th October 21:42
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