Temp, Oil and Ammeter Guages

[Deleted User]

Hi Richard,

is the 15-16v measured at the battery with engine running above idle or directly on the generator? if there is somehow 15-16v on the generator terminal but still only ~12v on the battery terminals then this will cause the light to glow dimly. The gen terminal should be approximately the same as the battery voltage when running fast. Sounds like the easiest thing is to borrow another regulator. They were used on so many cars that you don't necessarily have to find a Herald one.

The points opening occurs when the generator no longer produces any output and (you probably know this anyway) stops the current flowing back into the generator and draining the battery. Sometimes if the idle is a bit high the points stay closed because the gen still has a small output. Try winding down the idle speed and see if they open. My Herald has been swapped to an alternator but on the Zephyr I can hear a 'donk' sound inside the car when the points open, sometimes when it's idling high I have to let the clutch out a little in gear to reduce idle speed to get it to 'donk'. The main important thing is that they open when the engine stops completely or the battery will drain quickly.

Try shorting out your ammeter terminals or connecting both wires to the same terminal to see if it charges. Ammeters are just a bit of thick wire inside where the magnetic field created by current flowing deflects the needle left or right. Very simple but you never know, it could be faulty. Once you have sorted the charging fault, check the battery terminal voltage as per the manual procedure because adding an ammeter and extra wire can make the voltage at the regulator slightly different to the actual battery voltage. It may require you to adjust the regulator points to increase the battery terminal voltage back to spec or the battery will not get fully charged. I always think its kind of ironic that a gauge designed to show battery charging conditions can actually reduce the charging capability...

[all mod cons]

Great information there Andy. Thanks for explaining that.... and no, I didn't know what was actually happening when the points open.

Firstly, I carried out the tests you suggested in your last but one post. The one where you included the photo.

Interesting results. The points closed as the revs increased above idle. But in 9 times out of 10 they didn't reopen as I dropped the revs back to idle.
As you suggested, I could see the white sparks on the other relay when I revved to about 2000rpm.

So this is more evidence that the control box is faulty - the fact that the cut out relay does not re-open.

To answer the questions in your last post...
I measured 15-16v at the generator. I connected the two terminals together and then placed a voltmeter between this connection and the generator's casing (as per the Haynes instructions). I also put the meter across D+F at the control box - to prove the wiring back to the box. All Ok

Yes, I do see only just over 12V at the battery, even though the generator voltage is higher... and the dim red light.    

Right, I'll get hold of another regulator and also an ammeter aswell. I need another ammeter for my brother's Vitesse, so it's no great loss if it tunrs out that my one was working anyway.
Will let you know how it goes.
Richard.

[all mod cons]

Andy and all.
Today I fitted another control box. I found it on Ebay so it's not brand new but I think it has done the trick. The cut out closes and reopens as you described and for the first time since fitting it, the ammeter now shows a positive reading as follows....

The needle sits at zero on tickover. As I increase the revs the needle moves into the positive and a voltmeter I had on the battery increases from aorund 13.3V to 14.5-15V. This is a good sign !!
Just one question (there's always a question!).... when the ammeter needle gets to about +8amps, it suddenly starts flicking backwards and forwards quite erratically making it impossible to read. As I drop the revs it settles down again. Consequently it is impossble to read the meter when driving.
Is this normal behaviour or could I have a faulty guage?.... or maybe the contol box is still not working 100% correctly - it was a used box afterall.

Just one more thing I noticed when testing this while driving... when I put the lights on (full beam) the meter dropped to negative (about 15A I think), and the red ignition light came on and didn't go out for quite a while. It hasn't done this since so it may have just been a 'blip',

What is the normal reading I should see driving at say 60mph and then turning on the lights?

I know thuis thread is going on a bit but I think I've nearly got a working charging system thanks to everyone's help!!
Richard.


  

[Deleted User]

Hi Richard, good news eh!

Re the ammeter flicking, this is the current changing in response to those white sparks you saw on the regulator points. As the charging current reaches the max safe for the generator it creates a strong magnetic field in the relay (the one with the setscrew) until it pulls open the points. When it pulls the points open, the current suddenly drops, which closes the points and the current starts flowing again... etc. This is the flicking of the needle you see when the battery is down. It shouldn't be a crazy flicking if you ammeter is an OEM type one but possibly the flicking could excite the needle into a wild vibration if it is an aftermarket type. My Zephyr needle flicks at most by about twice the width of the needle and settles down to a gentle wiggle once the battery is charged.

What is the maximum current range written on your ammeter? Ideally you want a -30 +30A range as the max charge on a Herald should be about 22A (I think) and a -50 +50A ammeter will make the charge look a bit dismal.

Your ammeter should not go into negative territory when the engine is above about 2000rpm, even with all electrical loads on. When the battery is full and driving you are on the motorway, it should hover about half a needle width towards the +ve side, -15A is about right for headlights on, engine idling. On the motorway with battery charged, the regulator should compensate for all electrical load changes like turning on the headlights and keep the ammeter steady just above zero. Its really quite a clever unit a regulator, given that there's no transistors or anything in it.

The regulator relay in the box is both a max-current limiter and a max voltage limiter in one unit. Lucas found a bit later on that having two separate units (3 bobbin reg's as seen on later cars) gave better control, even so, nothing can match a transistorised alternator regulator for keeping the battery full...

[all mod cons]

Hi Andy,

It is a Smiths ammeter showing +30V to - 30V.

From what you're saying it sounds as if the ammeter may behave and stop flicking once the battery is fully charged. Perhaps I'll put the battery on a battery charger for a while to ensure it topped up the the maxmium and then see how the charging / ammeter behaves.

Do you think it sounds like this control box is working correctly? If not, now that I know that could be the probelm area, I may invest in a brand new one as TRGB do them for about £22 I think, and they aren't that far from me.    

I'll have to road test the car again, switching on the lights etc - just to ensure it doesn't go into the negative side of the gauge.
Appreciate all your explainations.
Richard.