Ammeter May Indicate a Problem

[8N457568Guy]

'52 Side Mount 6 Volt Positive Ground.

Following the good advice I recieved here, I replaced the wiring harness. All indications have been it was a success. The ammeter shows a slight discharge when turning over. When I start working the ammeter shows a charge at around 10 and then drops back to around zero.

It has been like this for a while now.

This weekend I replaced the really rotted thin negative battery cable with a 1 gauge.

Now the ammeter is pegged at 30. I was afraid to run it long, concerned that I would cook the generator.

Am I correct in being concerned?

 

[shaun wallace]

It was working correctly before changing cable. I put a charger on it for a while then see what it does.

 

[Dell (WA)]

Guy.......I certain what you wrote makes sense to you BUT you confuse me when you talk about ampmeter numbers without SIGNS!!!

Fer 'zample you write......"Now the ammeter is pegged at 30. I was afraid to run it long, concerned that I would cook the generator"......since the genny is only a 20-amp genny it is difficult to figger out how you're "pegged" at 30....unless....yer pegging in the NEGATIVE (-30) direction, in-which-case yer new negative battery cable is SHORTED to ground at the 3-terminal starter solenoid.

There is 'nuttin' mystical about replacing a BIG battery cable ...but... the little small wire from the solenoid battery terminal can be miss-connected or shorted. Unfortunately, my long-distance vision ability is compromised by the telephone wires. .......respectfully, Dell

 

[8N457568Guy]

The advice I get is often so good it seems there is a mind reader capability. . .

Pegged at 30 would be on the + side.

I hadn't thought about the 20 amp generater - See my prior posts about not being the sharpest tool in the box.

What in the heck did I do this time?

 

[GA Dave]

Think of your negative cable as the "HOT" wire. David............

 

[souNdguy]

before you 'fixed it' by changing the bat cable.. it was working correctly.

if it is no charging +30.. then the field is somehow shorted to ground on the genny.. or at the vreg.


pull the field wire at the gen see what it does.. then reconnect and pull it at the vreg.

if pulling it at the gen kills the charge, but pulling it at the vreg doesn't.. then you have a short from field to ground in the harness.

post back

soundguy

 

[8N457568Guy]

Yep, it seemed that things were working correctly before I changed the battery wire.

I hope to get some time Wednesday afternoon to work on it. I'll report back.

Thanks.

 

[8N457568Guy]

Well I have an update. Pulled the field from Generator killed the charge. As did pulling field from the VR.

So, I looked at the Ford Service Manual. Paragraph 69 provides trouble shooting guidance "A FULLY CHARGED BATTERY AND A HIGH CHARGING RATE indicate improper operation of the equipment and will result in battery overcharge and high system voltage. To check, connect test ammeter into the circuit at the "BAT" terminal of the regulator as shown in Fig. FO75 and disconnect the "F" terminal of the regulator. If the output drops off as the "F" terminal lead is disconnected, check the regulator for a high voltage setting or for grounds or shorts in the regulator. If the output does not drop off under these conditions, then the generator field circuit is grounded, either in the wiring or in the generator itself, and it must be removed for additional checking."

Installed a new VR today - that top bolt is sure a bugger - and fired it up. Quickly dropped to a few amps charge. Drove it a while, stopped and restarted the engine while watching the ammeter. Discharged while starting, went to charge and back close to zero.

Success.

So what happened? Stupidity that’s all. When I installed the new battery cables I dutifully re-polarized the generator. Except I "polarized" the field and armature. Total operator error.