Ammeter not reading zero

[Armycopter]

1969 Charger. I’ve searched and searched but can’t seem to find any reference to my exact issue. Ammeter seems to work perfectly but gauge is always negative. This is a picture of the ammeter with the key off. If I open the door or turn on the headlights it shows a draw to the left as it should. When the car is running, the ammeter is in this exact same position and again shows a draw if I turn on a blinker or headlights (only briefly and then returns to this same state of negative gauge indication).

Is there a way to get this gauge calibrated or adjusted to show zero in the resting state? (I.e. key off). This is an aftermarket ammeter and not the original.

FYI, my charging system is working well. I also have an aftermarket voltmeter that shows 14.6V while the car is running.

I understand I could just keep it this way but I’ve been working to get all my gauges working correctly and this is the last one. OCD in me wants this to be right.

Thank you

 

[davek]

Sounds like it is doing its job. Only thing you can do is pull it and have someone calibrate it to the right position. To me its fine the way it is. My oil gauge in the Bee says 10psi but my mechanical says 55psi. Yes it drives me crazy but not worth the time to pull it. JMO

 

[72RoadrunnerGTX]

If you are sure there is no discharge current flowing with the key off, disconnect the battery to verify, but otherwise appears to be registering normally, then it’s a calibration issue with the ammeter. That said, pretty easy to adjust, requires removing the ammeter however, tweaking the base of the needle slightly to center the indication in relation to the movement’s magnetic center position.

Just noticed the “aftermarket ammeter” comment. Assuming it’s not constructed identical to the original ammeters but there should be a similar process to adjust the indication slightly.

 

[twecomm]

If you disconnect the battery and its still indicating as you say, likely it just needs calibration. You could check with Todd, he can do a check out of the gauge and do a calibration.. Todd's Restorations – 66-67 Charger restoration

 

[Gold Rush]

Do you have any accessories connected to the battery or starter relay? The current draw from those will give you that exact indication. All accessories should be connected to the alternator feed side of the ammeter.

 

[dadsbee]

The one in my Bird sits staticly the same. When the day comes to pull the dash cluster out I'll center it. Until then, no big deal.

 

[Armycopter]

Do you have any accessories connected to the battery or starter relay? The current draw from those will give you that exact indication. All accessories should be connected to the alternator feed side of the ammeter.

That’s a good question. I do have an aftermarket stereo I keep in the trunk and it was professionally installed. I’m not sure where it gets power from. I’ll check that. Thanks.

 

[Armycopter]

Sounds like it is doing its job. Only thing you can do is pull it and have someone calibrate it to the right position. To me it’s fine the way it is. My oil gauge in the Bee says 10psi but my mechanical says 55psi. Yes it drives me crazy but not worth the time to pull it. JMO

Mine oil was doing the same thing. Turned out to be the sending unit. I bought one at O’Reilly’s and it made it worse. Someone on here recommended a different one that i had to order and it now reads the same as my mechanical oil pressure. That started me on the path of getting all my OE gauges to work correctly. Ended up doing the same with my water temp, and again, sending unit was the culprit.

 

[Armycopter]

Well, to wrap up this thread, the ammeter showed a negative (discharge) even when the battery was disconnected. I got into the rally dash and tweaked the needle to center with no battery connected. Once battery was reconnected, everything looks great. Stays center except when there truly is a draw. Slight positive when charging. Thanks everyone.

 

[72RoadrunnerGTX]

That’s a good question. I do have an aftermarket stereo I keep in the trunk and it was professionally installed. I’m not sure where it gets power from. I’ll check that. Thanks.

Professionally installed car stereo? Likely is connected directly to the battery, installers are taught to do so, some sound reasons for this and for most cars it’s not an issue. The sound system shouldn’t be drawing any measurable current with the key-off anyway. It will interfere with an accurate battery charging indication at the ammeter while in operation. If you want to eliminate mis-placed loads as the cause of the apparent calibration issue, disconnect the battery, see if it centers.

 

[72RoadrunnerGTX]

Well, to wrap up this thread, the ammeter showed a negative (discharge) even when the battery was disconnected. I got into the rally dash and tweaked the needle to center with no battery connected. Once battery was reconnected, everything looks great. Stays center except when there truly is a draw. Slight positive when charging. Thanks everyone.

Now, with the engine running, crank up the stereo. What is the change to the ammeter reading? If it shows an increase in charging, or false charging, the system is connected directly to the battery.

 

[Armycopter]

Yes it turns out it is connected directly to the battery. I will have to live with that for now. With the stereo off, it works as it should now. At least it seems to for now. Finally. Have all of my gauges working correctly. Photo of the car below, because why not?

 

[twecomm]

So many folks post about problems that are having on these forums. They get many suggestions on possible causes and things to look for and all too often, if they find the issue and solution it's never posted. Glad to hear you got it resolved, and thanks for posting what you did, may help others... Beautiful car !!

 

[Nacho-RT74]

Yes it turns out it is connected directly to the battery. I will have to live with that for now. With the stereo off, it works as it should now. At least it seems to for now. Finally. Have all of my gauges working correctly. Photo of the car below, because why not?

You wouldn’t have to live with that for now because the solution is easier than it looks. Is just about change the source from batt up to the alt stud and you are done.

Or EVEN EASIER! If the stereo is a regular one, without a big power plant, source it straight to the ammeter stud, black wire side. Will make a shorter wire and cleaner engine bay. Most of the modern stereo systems doesn’t get feeded by bigger than 16 or even 18 gauge wires so they are not a big suckers, so the bulkhead will hold the load to feed that system.

And as I allways say, upgrade the alt is a should (or must) thought. Even on a fully stock cars.

 

[twecomm]

Regardless of where the source for the stereo comes from, it should be fused at the source.

 

[ynst]

Remove the guage, bend the pointer so that is correctly centered and put it back together.

 

[JimCoronette]

Yes it turns out it is connected directly to the battery. I will have to live with that for now. With the stereo off, it works as it should now. At least it seems to for now. Finally. Have all of my gauges working correctly. Photo of the car below, because why not?

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Haha, I have the exact same cupholder in my 67. I love it!

 

[Krooser]

Bend the needle until it charges..

 

[Archie Duiker]

Now, with the engine running, crank up the stereo. What is the change to the ammeter reading? If it shows an increase in charging, or false charging, the system is connected directly to the battery.

I have a similar problem where the ammeter always reads high on the charge side. I have an EFI conversion with electric fuel pump that was wired directly to the battery as per manufacturer instructions. So based on your comments, can I assume there is nothing wrong with my charging system? My voltage at anything above idle reads between 14 & 14.4 volts.

 

[72RoadrunnerGTX]

I have a similar problem where the ammeter always reads high on the charge side. I have an EFI conversion with electric fuel pump that was wired directly to the battery as per manufacturer instructions. So based on your comments, can I assume there is nothing wrong with my charging system? My voltage at anything above idle reads between 14 & 14.4 volts.

There are some valid reasons why aftermarket manufactures dictate power connections directly from the battery, for every other car out there, no issues. Number one reason, installers, professional and otherwise, can’t be trusted to identify adequate alternative power connection locations other than at the battery posts. On the original Chrysler ammeter-based charging system there are repercussions to doing so, including a false charge indication on the ammeter and current stressing wiring/connections, and components not designed for the added current load. Details in this thread/video. As well, suggestions as to how to power those mentioned added loads not at the battery.
Factory original Chrysler ammeter-based Charging System and additional loading. Load placement matters!