Well, I'm back again with some bothers with the charging circuit.
I . ordered one of those LEDs , but I ordered a standard one.
With the motor running, It flashes once red for 12.4 volts. I measure 17+ at the alternator so I figured there was a problem with the regulator .
The needle on the panel meter is far right.
The reading across the battery terminals is also 12.4 with motor running.
Since someone had buggered the wiring on my car before I got it, I have had to trace just about everything. All wires to the regulator are the same color so I traced one (D+) to the alternator, (D-) went to ground and the other wire went to the coil (Mv connection).
I though maybe the regulator was off so I tried a replacement-no change except now I have lost my oil pressure light.
Would anyone be so kind as to express an opinion as to my next move?
I know these electrical glitches are tricky, but the more I do the worse it gets. Help!!!

Hi, I'm not sure that you have a problem here. Where did you measure that 17+ volts at the alternator? The big terminal held on by a nut is connected directly to the battery, via the starter terminal, so the voltages at the alternator and battery will be the same, if they're not you need to check the connections.

12.4 volts is about right for a battery at rest, but you should have more like 14v when the engine's running, try raising the engine revs a bit to see if the voltages increases.

The regulator sounds ok, there should be a live wire for it in the loom, it shouldn't be connected to the coil, although it will work like that.

The live wire for the regulator from the loom uses the same fuse as the oil warning light, so if that wire got shorted to earth while you were changing the regulator then it could have blown the fuse, if your indicators also don't work, that proves it. The other possibility is that you just disturbed a bad connection while you were working.

Hi Joolz.

As socaro says, I'm not sure if anything is actually wrong here. The alternator WILL give out a much higher voltage than is required by the car - and its output will increase directly with engine speed. 17+ volts sounds fair enough!

That's why you need the voltage regulator - its purpose is to, yep, regulate the alternator's voltage and keep it down to a level that'll supply the demand required of the battery and circuits whilst not allowing it to increase to the point the battery is cooked and bulbs start to blow...

So, you will measure a larger and much more variable voltage directly at the alternator. What the battery receives shouldn't go much above 14V, and that's usually only after you've first fired up the car and the battery needs a top-up. After the battery is charged up, the voltage across it should drop steadily down to 12-13V, I believe.

I'm sceptical about your theory DA. I believe, but may be completely wrong, that although some regulators, (on motorbikes I've looked at) take the alternator output and 'chop the top off' it, car regulators like the 2cv's work by switching off the exc supply when the output tries to go too high.

And to repeat what I said before, the regulator doesn't intercept the output from the alternator, there is an unbroken connection between the alternator output and the battery + terminal. Therefore the voltage on the two will be the same.

The only way the alternator could give an output of 17v is if its exc connection is given a permanent live feed, either through mis-connection or by a faulty regulator.

*The first paragraph may be bollocks, I'll wait to see if any guru agrees with me.

Oil Pressure light -

Mine went out a week ago...didnt understand it .... got a bit worried...but it was the connector on the headlamp bar (can't remember the colour)....just dropped apart. Check all connectors !!!

Joolz,
you've got good reason to be sceptical of DA's theory, as it's full of errors.
If an A series regulator is working correctly, the system voltage should be 14.4 volts when charging.
Anything over that spells trouble...

ken
(who remembers Brit bikes having Zener diodes to 'clip' the output from their puny alternators. )

Oops, first my apologies for getting your names mixed up - I should have started with "Hi socaro. As Joolz says..."

I also take on board your description of how the regulator might work on the 2CV - clearly quite different, then, from the early cars I am used to which have 'trembler' regulators controlling the output from dynamos.

I missed the part where the alternator output is explained as being connected directly to the battery. Mind you, how can socaro's battery then show only 12.4V when the alternator it is connected directly to is showing 17V+; the voltages at each end of a continuous wire should be the same (unless there's a high resistance connection before the measuring point)?

Anyways, I clearly don't know enough about 2CV charging circuits to say any more - so I'll read the rest of this thread instead!

Yup, A quick trip to my local Auto Electrico put the regulator connections right-I'd been having trouble matching the D+, Df with Mv, J , Bc, etc- since the wires were all same color.
And the blown fuse-when I apparently made a wrong connection, didnt help.
Also my apologies for misleading some of you with the 17+ output from the alternator. That was incorrect, the reading should have been 12.4 which was the battery voltage since the field was not being energized.
Finally, I really like that little LED.. There is always a warm and fuzzy feeling when your battery is charging. Thanks to all for listening.

socarco,
at least one manufacturer of electronic voltage regulators makes life easier for those folk who have to deal with a butchered wiring loom.

Mind you, it's still necessary to know how to use a multimeter...


Badge engineering? by slcchassis, on Flickr