Amperes Meters are never at zero?

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Mopar_man
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Amperes Meters are never at zero?

Post by Mopar_man » Fri Sep 10, 2021 10:42 am

So are all the Amperes Meters at -1 Amp when the ending is off and Bat disconnected? Or just at the swap meet. Seems like they all look like this:
IMG_4852.jpeg

My concern is when I set the third brush. Are you supposed to compensate for that one amp? Or do you just go off what it reads as you make your adjustment?

The car is all stock except I will be using a Voltage regulator from the old Fun Projects company that I was able to buy.


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Re: Amperes Meters are never at zero?

Post by Norman Kling » Fri Sep 10, 2021 10:56 am

I have never seen one which looked like that one. The pivot point looks like it is not lined up with the dial, however, it still points near zero! Anyway, whatever it reads with everything disconnected is zero amps. If you are concerned about the accuracy, connect an analog ammeter in series with the wire from the generator and adjust it according to that meter. Then with the engine off, remove the meter and re connect the wiring. I have never used a voltage regulator, but I would think it would automatically adjust the current as needed.
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Re: Amperes Meters are never at zero?

Post by Scott_Conger » Fri Sep 10, 2021 11:03 am

Original late ammeters are always off/inaccurate. Repros just amplify that.

Followfollowfollow the FunProjects instructions!!! It was bad enough years ago to smoke one by being careless or knowing more than the designer, but now it would be a crying shame to smoke one as replacements are so scarce.

Start with a standard cut-out on the generator, and use "wherever the needle sits" when everything is "off" for your "zero". Don't ignore the offset of the needle. Set your output to 3-4A. That's plenty. If you can't achieve that, then reset the null in the generator, as well as output as detailed here: https://modeltfordfix.com/adjusting-the ... patterson/
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Re: Amperes Meters are never at zero?

Post by Mopar_man » Fri Sep 10, 2021 11:04 am

Maybe that the issue. The pivot point might be off.


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Re: Amperes Meters are never at zero?

Post by MichaelPawelek » Fri Sep 10, 2021 11:05 am

I don’t believe those were ever made to be that accurate as drivers don’t pay much attention to them. You start the car and the needle moves until the battery is charged. You turn on the lights and the needle moves etc. They are just basic indicators of charging or discharging. I would never use one to set the generator brushes.
Last edited by MichaelPawelek on Fri Sep 10, 2021 12:03 pm, edited 1 time in total.

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Re: Amperes Meters are never at zero?

Post by Mopar_man » Fri Sep 10, 2021 11:40 am

Thanks for all the input. I'll use where it sits as the zero.


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Re: Amperes Meters are never at zero?

Post by TXGOAT2 » Fri Sep 10, 2021 12:32 pm

They aren't very accurate, and many have been dropped or subjected to a heavy discharge by a short circuit. That can bend the movement and cause more inaccuracy, which often shows up as a failure of the needle to find center when everything is off. Back in the day, Ford mechanics were advised to use an accurate "master ammeter" to set charging rates and do electrical system diagnosis.


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Re: Amperes Meters are never at zero?

Post by GridLeak » Fri Sep 10, 2021 5:36 pm

could be the dial needs a twist. as said they aren't accurate. use a aa battery across it in both directions it will read different even it reads 0 at rest.


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Re: Amperes Meters are never at zero?

Post by Scott_Conger » Fri Sep 10, 2021 5:50 pm

I'd think a person would really have to hate their ammeter a LOT to put voltage across it... :shock:
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Re: Amperes Meters are never at zero?

Post by TXGOAT2 » Fri Sep 10, 2021 6:13 pm

I wouldn't be afraid to put an AA battery (cell) across one, but they typically have a very low internal resistance, and connecting a significant source of current directly to one would damage or destroy it. Most all common dashboard type ammeters are the moving vane type, and must be connected in series with other devices, such as lights, ignition systems, etc. which have enough internal resistance to prevent the total circuit current draw from exceeding the ammeter's capacity, which is about what the highest number on the dial face is. Ford used an ammeter on 1940's cars that simply had the body feed wire clipped to the back of the instrument. Current did not flow thorugh it; only past it. Automotive ammeters are designed to show which way the DC current is flowing, and give a rough approximation of how much current is flowing. They are not sensitive enough to detect small current leaks or small loads, like a glove box light that is staying on and draining the battery overnight. On vehicles with alternators, the ammeter, if any, indicates the rectified DC current flowing to the battery or to the loads. I doubt if they're very accurate. Connecting a typical auto ammeter directly across a 6 or 12 volt car battery will destroy it in an instant, and could cause personal injury due to burns and flying glass.


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Re: Amperes Meters are never at zero?

Post by John kuehn » Fri Sep 10, 2021 6:38 pm

In just taking a look at the first pic and not making any comment about the accuracy or use of an amp meter the amp meter in question does look like the needle is not lined up at the pivot point.
In other words the face is either off center or the pivot point is off center.
Maybe it’s because the picture of the meter was taken at a slight angle and not directly straight at it.


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Re: Amperes Meters are never at zero?

Post by Allan » Sat Sep 11, 2021 12:16 am

It's a chrome plated repop, of dubious quality. If you look closely the 20 on the discharge side is well under the rim of the meter while the 20 charge side sits nicely within the bezel. This shows the face is well off centre, to the discharge side, and still the needle points further to the left. Use it as an indicator rather than an accurate meter.

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Re: Amperes Meters are never at zero?

Post by GridLeak » Sat Sep 11, 2021 8:53 am

a aa doesn't deliver much current it will read about 5 amps. any 1.5v battery will do the same. when someone figures out how to produce current without voltage let me know. it will help in perfecting my perpetual motion machine.

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Re: Amperes Meters are never at zero?

Post by mbowen » Tue Sep 14, 2021 6:19 pm

Mopar_man, it looks like the meter face (thin cardboard on my 1925) is improperly indexed on the meter housing, and someone reindexed the meter in the mount to compensate. If you’re careful you can open up the meter and properly index the face. The cardboard face is indexed to a steel ring which in turn is indexed to the housing. The glass lays against the face, and the plated trim ting holds it all together. (Sorry for the sideways photos, but the forum won’t accept portraits.)

(As far as testing the meter, any DC source incapable of delivering more than 20 amps can’t hurt the meter; that’s what it’s designed to carry. I just repaired an internal open circuit in mine, then tested it with an AA battery and got results close to what GridLeak said in the previous post.)
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Re: Amperes Meters are never at zero?

Post by Mopar_man » Tue Sep 14, 2021 9:56 pm

Thanks again everyone. For now I used the place of the needle as my zero and adjusted it from there. I may try to play with the meter face in the future.

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Re: Amperes Meters are never at zero?

Post by TRDxB2 » Tue Sep 14, 2021 10:01 pm

Mopar_man wrote:
Fri Sep 10, 2021 10:42 am
So are all the Amperes Meters at -1 Amp when the ending is off and Bat disconnected? Or just at the swap meet. Seems like they all look like this:
My concern is when I set the third brush. Are you supposed to compensate for that one amp? Or do you just go off what it reads as you make your adjustment?

The car is all stock except I will be using a Voltage regulator from the old Fun Projects company that I was able to buy.
Properly assembled & working ammeters point to zero when the engine is off and the battery is disconnected. Some older ones may have the pointer off center from bending or face plate misalignment. Your ammeter is a repro, suspect the switch is too, in any case it may be that the ammeter was not assembled properly. The bezel can be removed, some tabs bent in, then rotate the face plate so the pointer is at 0. If that doesn't work, discard it and get another one. Repro's about $13 + shipping. Also the same with out FORD script at local Auto or Farm Parts supplier 20-20 range is correct 30-30 works too
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Re: Amperes Meters are never at zero?

Post by Mopar_man » Wed Sep 15, 2021 10:57 am

As usually the case you guys are right my meter is canted. It's way too shiny to be an original. Same with the switch.

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Re: Amperes Meters are never at zero?

Post by JBog » Wed Sep 15, 2021 11:32 am

Mine wasn't at 0. I took it apart and bent the needle until it was at 0 and it is working fine.


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Re: Amperes Meters are never at zero?

Post by Been Here Before » Wed Sep 15, 2021 12:00 pm

Question, by bending the needle to zero, what guarantee do you have that the meter is reading the proper amperage? Generally there should be a standard amperage to calibrate the meter.

Calibrating and testing analog meters - Yokogawa
https://cdn.tmi.yokogawa.com › files
PDFThe measurement functions of signal conditioners can be calibrated and tested by the value of temperature or resistance using analog signals (1 to 5 VDC, 4 to ... 8 pages


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Re: Amperes Meters are never at zero?

Post by TXGOAT2 » Wed Sep 15, 2021 1:34 pm

Adjusting the movement to show 0 when appropriate is probably good enough. The stock meters were not very accurate, the electrical system is not the most stable, and the dial face, pointer, and movement of the meters is not designed for accuracy. I doubt if a typical dashboard ammeter would hold accuracy very well in service, even if you could get it to read accurately. Ford recommended use of a master ammeter to make generator adjustments in Ford service shops, citing the unreliability of the dashboard units.


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Re: Amperes Meters are never at zero?

Post by speedytinc » Wed Sep 15, 2021 2:23 pm

I dont mess with a stock ammeter for fear of damaging & needing the far inferior repops. If a stock meter shows 1 amp @0, thats my zero reference. @ 5 amps charge(actual) it shows 6. Dont matter. I generally check the system with a modern analog meter to see if the readings are close enough. I set the gen output to 0 or slightly negative with the lights on. I would not expect a crappy repop to read accurately or on old original to be accurate either.
In this case, I agree with turning the off face to show 0. Nothing to loose. Untill you test it independently, dont count on the readings to be accurate.

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Re: Amperes Meters are never at zero?

Post by JBog » Wed Sep 15, 2021 2:46 pm

Been Here Before wrote:
Wed Sep 15, 2021 12:00 pm
Question, by bending the needle to zero, what guarantee do you have that the meter is reading the proper amperage? Generally there should be a standard amperage to calibrate the meter.

Calibrating and testing analog meters - Yokogawa
https://cdn.tmi.yokogawa.com › files
PDFThe measurement functions of signal conditioners can be calibrated and tested by the value of temperature or resistance using analog signals (1 to 5 VDC, 4 to ... 8 pages
Yea, there's no guarantee it was accurate to begin with. When I adjusted my generator, I used a multimeter to read the amperage and get it to in the ballpark of ~5 amps. On mine, the needle bounces around so I can't be sure it's at precisely 5 amps anymore, but it tells me it's in the ballpark and if the generator is doing its job.


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Re: Amperes Meters are never at zero?

Post by speedytinc » Wed Sep 15, 2021 5:12 pm

JBog wrote:
Wed Sep 15, 2021 2:46 pm
Been Here Before wrote:
Wed Sep 15, 2021 12:00 pm
Question, by bending the needle to zero, what guarantee do you have that the meter is reading the proper amperage? Generally there should be a standard amperage to calibrate the meter.

Calibrating and testing analog meters - Yokogawa
https://cdn.tmi.yokogawa.com › files
PDFThe measurement functions of signal conditioners can be calibrated and tested by the value of temperature or resistance using analog signals (1 to 5 VDC, 4 to ... 8 pages
Yea, there's no guarantee it was accurate to begin with. When I adjusted my generator, I used a multimeter to read the amperage and get it to in the ballpark of ~5 amps. On mine, the needle bounces around so I can't be sure it's at precisely 5 amps anymore, but it tells me it's in the ballpark and if the generator is doing its job.
Does it bounce with the motor off & headlights on?? If not, there may be another issue, or you would expect this with a true voltage Regulator.
Fun projects unit??

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Re: Amperes Meters are never at zero?

Post by JBog » Wed Sep 15, 2021 5:28 pm

speedytinc wrote:
Wed Sep 15, 2021 5:12 pm
Does it bounce with the motor off & headlights on?? If not, there may be another issue, or you would expect this with a true voltage Regulator.
Fun projects unit??
Mine bounces a little bit at moderate idle. I don't have a true voltage regulator, I thought those VR cutouts were no longer in production.


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Re: Amperes Meters are never at zero?

Post by speedytinc » Wed Sep 15, 2021 5:31 pm

JBog wrote:
Wed Sep 15, 2021 5:28 pm
speedytinc wrote:
Wed Sep 15, 2021 5:12 pm
Does it bounce with the motor off & headlights on?? If not, there may be another issue, or you would expect this with a true voltage Regulator.
Fun projects unit??
Mine bounces a little bit at moderate idle. I don't have a true voltage regulator, I thought those VR cutouts were no longer in production.
True, but you might have had one to explain an expected electrical bounce.

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Re: Amperes Meters are never at zero?

Post by JBog » Wed Sep 15, 2021 5:35 pm

speedytinc wrote:
Wed Sep 15, 2021 5:31 pm
True, but you might have had one to explain an expected electrical bounce.
Ohh okay! Got it.


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Re: Amperes Meters are never at zero?

Post by Piewagon » Wed Sep 15, 2021 10:06 pm

The pictured ammeter is a very cheap reproduction that is sold for cheap. It is not exactly the type used during 1926 and 1927 and is generally referred to as the "SMALL METER" but the Ford original meter of the same typical size was a better meter. The off center tilt to the needle is common for that cheap repo item. The original larger meters made by Ford were more accurate although some of them "bounce" a bit while you are driving and some makers of the Ford "Large" meter (arrives in 1919 model T's) were better than others that Ford got their meters from. Hoyte meters were better and lasted longer. The ones I got involved with were more accurate than Ford's original versions but that is simply because the technology improved in later years and the movements can be very stable and very accurate (typical 5% of full scale). The small meter just doesn't work very well and Ford never chrome plated any of their meter bezels. Original small maters had a rim that was flat and nickel plated. They were better quality by a mile than current reproduction small meters. You get what you pay for I guess.


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Re: Amperes Meters are never at zero?

Post by Alan Long » Wed Sep 15, 2021 10:17 pm

I suppose we are lucky to be able to buy a meter at all these days however if a quality and correct looking
Meter was available for my 26 T I would pay the asking price for it!
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Re: Amperes Meters are never at zero?

Post by Mopar_man » Wed Sep 15, 2021 10:54 pm

I may look for another one in the future. This is the one that came with the car so I'm going to use it for now. I'll keep my eye out for a better one.

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