Amp meter not showing charge

[Bob Wright]

New restoration on a early 1931 Victoria. I'm using a 6-volt battery, (new), alternator (had checked-out @ reputable shop, OK output of a little over10-volts. The amp meter doesn't show charge, lights,horn,etc. show discharge
but can't get a charge reading even when the engine is revved-up? All the wiring is new. I've used the same set-up in our previous A's with no issues, worked great, what am I missing
Bob

[Tom Wesenberg]

10 volts is too much for a 6 volt alternator. Open circuit output should be regulated to 8 volts or a little less. This still doesn't explain the ammeter not showing a charge though. Some repro ammeters have sticking needles and don't move well. I like to put a drop of heavy oil on the needle pivot points, both for the original and repro meters.

[Mitch//pa]

i always ck the actual rates with an external meter
usually the built in ammeter for me is just a go or no go device

[Jim Brierley]

a friend brought me a mid-50's gmc to look at with the same trouble. turned out to be loose wires on the ammeter. worth a look.

[JackA]

Does it show discharge with lights on?

[Bob Wright]

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Tom,
I replaced the meter and the result was the same though. Will try the drop of oil.

[Bob Wright]

Jim, The connections @ the meter ere snug. Thanks

[Bob Wright]

Yes. Jack

[Tom Wesenberg]

The only thing that makes sense to this situation is if the needle hits something on the charge side, to stop it from moving more.

A lot of these type problems seem like they would be very easy to solve in person, but are tough over the internet.

[KMeredith87]

Had a similar issue a few years back...ended up a had the wrong regulator in the alternator. If you're trying to run it one wire ensure you have a self excited regulator or if you do not then jump the regulator so it will begin the charging process.

[Patrick L.]

You didn't state what alternator you are using. But, with key on does the front pulley try to hold a wrench/screwdriver [ magnetic] ?
Does the rear half have a 'D' slot and if so have you tried inserting a screwdriver to full field/jump the regulator ?

[Willie Krash]

A 6v alt should put out 7.25V - 7.5V max. If the shop tested it on 6V battery you may see 10V with everything going to current if it has a 12v regulator.*

Personally I would go back to the alternator and correct that issue.

Once you have a 7.25V alt I would check voltage at the batt. terminal and the Battery itself running with load and w/o load.

* if it is a 12v analog VR (10si) the power transistor will latch in full field position waiting for it 14V set point. It will not be able to do that on a 6V battery so it will just go to full current waiting for it's set point to be reached. Hence you could see 10V. In other words the VR thinks the battery is dead and will try to bring it to 14V.

[Bob Wright]

P.S. That was my reading with a very good digital VOM.
Bob

[Mike V. Florida]

Originally Posted by Bob Wright

I've used the same set-up in our previous A's with no issues, worked great, what am I missing
Bob

While you are having your alt checked, and you should have it checked,

Are we to take your statement above as you are not using stock wiring? Do you have a drawing of what you are using?

Unless you are having real bad luck with ammeters, (did you place a flashlight battery across the meter to see if it moves), it can only be the alternator or the wiring to the meter.

[Bob Wright]

Mike,
The wiring harness is from Bratton's and I believe there made by S.V.F.

[Mike V. Florida]

Originally Posted by Bob Wright

Mike,
The wiring harness is from Bratton's and I believe there made by S.V.F.

OK check the meter and re check the wiring, but your alt does have a problem if it is putting out 10 volts.

Model a wiring diagram

[Bob Wright]

Thanks to all that responded. I'll post my findings on what is found.
Bob

[Bob Wright]

Took the car to alternator shop and had the alt. tested in the car with the engine running. All readings, amperes & voltage were correct. When I have some extra time I'll rebuild a original unit and replace the junked meter.
Thanks to all who responded.
Bob

[Mike V. Florida]

Originally Posted by Bob Wright

Took the car to alternator shop and had the alt. tested in the car with the engine running. All readings, amperes & voltage were correct. When I have some extra time I'll rebuild a original unit and replace the junked meter.
Thanks to all who responded.
Bob

If it were me I would not go back to that shop. That is just me. A properly rebuilt and working 6volt alt has a regulator that prevents the unit from putting out 10 volts as 10 volts will toast a battery in short time.

[Bob Wright]

Alternator mystery solved:
Yesterday I decided to give one more try to find the Alternator pproblem. before calling in the experts. So I tested the voltage of the battery (without the engine running (hadn't done this before) , the reading was 8.2 volts, oops. Looked for ratings on top of the batt,none. Then pulled the unit out and there it was, on the side,-"8"- volt, I had originally ordered a 6- volt unit & assumed that I received same (dumb me), didn't even catch the 4-cells instead of the 3 that it should have had? Then I knew immediately what the problem was, the alt. was seeing a high voltage and wasn't trying to replace the voltage it should have been seeing. Installed correct batt, and now were ready to do some great touring. Thanks to all who offered there thoughts,
Bob

[1931 flamingo]

Thanks for the "update".
Paul in CT

[Mike V. Florida]

What about the ammeter?

[stouchton]

Originally Posted by Mike V. Florida

What about the ammeter?

With the battery voltage above the alternator voltage it would not charge (no reason too) - so no current.

However, in the future if you think you have a bad ammeter that doesn't show charge, merely reverse the connections on the ammeter and turn the headlights on. Now it should swing to the right during discharge. If not, it is defective.