Classic Alfa Forums

Since buying my sud I’ve been chasing a problem which I’m not actually sure is a problem, or just a quirk.

The car hasn’t ever failed to turn over, hasn’t conked out when running, hasn’t actually broken down.

I have noticed that when driving at night with the lights on, interior fan on and wipers on, the battery light will glow slightly. It never comes fully on, but is bright enough that I can see it, and gets brighter and dims with each stroke on the wipers.

So far I have checked the alternator, fitted a new voltage regulator, built a hybrid alternator using the internals of a Mk2 golf 65a alternator with the front half of the sud one. Checked battery terminals, checked the main earth strap, cleaned up all the connectors to headlights, to the column stalks, to the dials, to the wiper motor etc.

I have fitted a relayed headlight supply to take load off the main power feed into the car, and replaced rear lights, sidelights and indicators with leds to further reduce electrical load. I have cleaned up the contacts in the column switches as well as you can without taking the whole thing to bits ( and probably breaking it )

Any other suggestions, or am I worrying for nothing? As I say, it’s not actually caused a problem as yet, I just don’t like seeing the feint glow of the battery light.

All my suds did that. I wouldn’t worry about it.

Mine too!
If it bothers you, stick a bit of masking tape over it!

The old car service managers saying when you take the car back "they all do that sir!" applies here. I've done everything on mine like you have including putting thicker cables to the alternator and battery. And guess what? The battery light still glows underload

Not helpful I know but think I've only driven mine in the dark a handfull of times in 11 years.

I can confirm this is not unusual .

Like the guy who went to the Doctors.

" I can't stop singing old Tom Jones songs"

My MoT guy told me a tail light was out.
Then said " you don't use it at night though do you"

Thanks all, I’m quite happy to ignore it if it’s fairly normal.

To join the chorus: mine does that as well....but not all the time! The warning bulb operates on a differential voltage, alternator output on one side and battery voltage on the other. When the engine is not running one side of the bulb is connected to 0v via the alternator/regulator with the other at 12v, so it lights up. With the engine running you have 12v either side of the bulb so it goes out....if there is some resistance in the wiring to the bulb on either side it will cause a voltage drop and thus a voltage differential and the bulb glows....

The wire from the alternator is also called the exciter and, as I understand it requires a small current draw to magnitise the field coil in the alternator so it can generate a voltage....

My late Auto electrician told me that with the engine running, I should get approx 14.4V across the battery terminals.
Proves the alternator is doing its job.

Ditto as above but just to say nice fleet Harry

I can add that my 83 sprint does this too... had alternator overhauled....and still does it... but battery doesn't go flat.... so not worried.
Peter

Thanks, I was reasonably happy that the things I’d checked and done showed everything was working fine, and it hadn’t actually caused any issues, it’s just that niggle there and not knowing whether I’d missed something or it’s nothing to worry about.

I’m happy to ignore it unless it comes on as bright as when you turn the ignition on!