Generator not charging - maybe ?

M

masipopa

Member
Hi,

I have for about a year Ford Model A Sport Coupe. I'm new and learning my way while fixing here and there, thanks to all great experts here.

My Ford is an older restoration - 12v ground positive.

The current issues is that ammeter never goes positive. It does show dis-charge with lights, starting, etc. The battery is not going dead so cutout seems to be open.

When the engine is not running I'm measuring -12.5V at point A and zero at point B (see picture 1)
When the engine is running I'm measuring -12.2V at point B.

What could be the issue here - ammeter, cutout never closes or generator not producing enough ?

Also if it a cutout, is it possible to take the top off and see if the points close ? I read about the diode replacing. Is it a good idea to replace with a diode and where to find a 12V ground positive replacement diode ?
 

Attachments

  • IMG_2951-1.jpg
    IMG_2951-1.jpg
    95.7 KB · Views: 61
  • IMG_2952.jpg
    IMG_2952.jpg
    47.4 KB · Views: 48
Last edited:
If it's a original cutout the top is spot welded on
If you take off the belt, take wire Aoff and touch to B the generator should turn( called motoring), this will do 2 things, first it will polarize the generator (start some magnetism of the correct polarity in the field coils), and if the generator turns like motor that there's a good chance that it can work ok.
It's possible that when it was converted it was negative ground--- a stock generator/cutout can be either polarity, a diode cutout has to be for the polarity being used.
 
1. Since you say that the battery is not running down I would ask if there is a Fun Projects Voltage regulator installed on top of the generator.

There is a version that you can buy which has the Ford script on top.

CAUTION: If it is in fact a Fun Projects regulator and if you jumper the two terminals as installed on generator the regulator will be destroyed.

Following what Kurt said should be OK

If you do not know if it is a Fun Projects regulator it is best to follow the instructions on their website which tell you to remove regulator from generator BEFORE any testing is done.

It looks like the website has been taken down so I do not know where you get the instruction sheet anymore.

Also when checking for voltage on the input to cutout OR regulator, the engine must be above idle speed.
 
Last edited:
Hi Benson,

I don't know if this is a Fun Project Regulator. Should I un-bolt it and take it off before putting a jumper ? What would it say at the bottom ?

When I checked the voltage, the engine was in fast idle.
 
masipopa said:
Hi Benson,

I don't know if this is a Fun Project Regulator. Should I un-bolt it and take it off before putting a jumper ? What would it say at the bottom ?

When I checked the voltage, the engine was in fast idle.
Click to expand...

Yes unbolt first which is what the instructions say.

I do not have a copy here it is on machine at home.

As I remember John Regan posted once how to tell by looking at the bottom of it. I do not remember details or if I kept a copy.
 
Last edited:
Deleted: "Seems strange to me that Mac's sells "

Google search took me to Mac's ... looks like that is a cutout as mentioned above. Xin Loi.
 
Last edited:
Benson said:
Seems strange to me that Mac's sells the FP regulator and nothing is mentioned on website about the instruction sheet and the cautions it contains there are 4 or 5 cautions ... I guess not after thinking about it ...
Click to expand...

To my knowledge, Macs does not sell the Fun Products cutout/regulator. They sell a basic imported diode cutout.
 
Is that a 12 volt generator? The cutout will only close when the generator is putting out more voltage than the battery voltage. If you have a 12v battery, but a 6v generator....
 
The generator will produce whatever voltage is required by the battery.
The cutout shown is original. Stampings are ~1930, I believe; mounting pads aren't slotted.
Generator must exceed battery voltage in order to operate the cutout.
Two types of diode cutouts - positive or negative ground, not voltage dependent.

Ordinarily you could adjust the third brush to increase the output, but your generator has been modified internally, or may not be for model A. You'll have to open it up to see what you have.
 
Two wires coming out of generator I think is later not an A generator ? The wire going to the cut out mounting screw, I would remove and clean and reinstall ! Hopefully it's a bad ground.
 
Thank you all, but something isn't making sense for me.
How can i measure -12.2V at point B when the engine/generator runs ? Shouldn't it be the voltage generated by the generator assuming the cutout stuck in open position.
 
You are seeing 12.2 because that is what it is charging at. IF its a stock cut out points stuck open will very quickly burn out the generator. It behaves like it has a VR. If bat is charged the ammeter will show no charge
 
jetmek said:
You are seeing 12.2 because that is what it is charging at. IF its a stock cut out points stuck open will very quickly burn out the generator. It behaves like it has a VR. If bat is charged the ammeter will show no charge
Click to expand...



I agree that is sounds like some kind of regulator is installed.

That is why I asked if a A Fun Projects regulator was installed.

Also it could be that there is one of the several types of regulators installed inside of the generator.

Seven or eight years ago I saw such a "generator run away" failure at the Georgetown Hill Climb.

The guy was wound out in second gear when very loud "BANB BANG Backfire".

He shut down and rolled over to the side of street before the sharp left turn.

Investigation showed that the ignition points looked like someone had attached an ARC welder to them with melted steel, copper and brass splattered all over inside the distributor.

The generator had gone to over 40 volts when the battery cable fell off.

The battery cable clamp had not been tightened after it was taken off the trailer
 
Last edited:
That's a diode cutout. Hard to sell anything "electronic" for $20.

Recheck your voltages. Gen should be .6v-1.2v above battery side. Difference is forward voltage drop of the diode.

It looks to be a later two brush generator, which used a three-relay regulator. Without the third brush there's no way of adjusting to avoid overcharging the battery.
 
You must log in or register to reply here.
Back
Top