Ammeter question....

[Richard]

I did a full harness rewire last winter/spring. (new harness, new ammeter / instruments, new lights, batteries, ignition switch.... virtually EVERYTHING except for the tach and water/oil info. I even replaced the button for ignition and the other button for the ether.

I'm confused on the Ammeter although I THINK I followed the directions correctly. If I DID then I'm simply confused how it works.


My understanding / presumption: When the tractor (IH-1066 btw) is running and for example, the lights are on, the ammeter would be on the LEFT side of "zerro" as you no longer have a full charge and as the batteries get to full charge, it will "tend towards zero"

What is happening (and my presumption of what it means).... when tractor is running, the ammeter is actually in the slight positive. I turn the lights on and it goes FURTHER into the positive (right side of meter). What I'm presuming THAT means is it's showing me how much power is being drawn off the alternator. Turn the lights on, uses more juice....so it goes FURTHER to the right showing that it's creating more juice.


Question: What has to happen to have it show on the LEFT side of zero? I've never (ever) seen that happen yet. I've been out there with LOW batteries (enough to have to jump start) yet, when it starts, it's showing a pleasant "slight positive", turn lights on and it shows MORE positive.

I'm somewhat baffled..... but then.... I'm THINKING it's reporting back to me the charge in the battery. If instead it's ignoring the battery and instead, telling me how much power the alternator is providing, then it seems to make sense.


So, what part of above, do I have totally wrong, slightly right or other??

 

[Ford850]

It's measuring current, so it would only show negative if you reversed your polarity. Ask me how I know.

 

[CobyRupert]

Ammeter = amp meter. Amps are a unit of Current. Electron flow.

My memory is:
Typically current "from" the battery, when alternator output does not match load, or when engine is off and battery is supplying all current: Meter is negative (left side of zero).
When battery is charging (current "to" battery), meter shows positive.

Your Ammeter's behavior seems to be measuring current from the alternator, not to/from the battery.

My guess is there won't ever be current going to the alternator, so that's why it never goes negative.

If OPe reversed the polarity, but it's measuring current from/to battery, doesn't that mean his battery is slight discharging when idling, and discharging even more when he turn the lights on. Wouldn't this mean OP's alternator isn't working?

 

[ovrszd]

Let's confirm that you have an alternator rather than a generator??

If you have an alternator wouldn't you benefit more from a volt meter rather than an amp meter?

Your amp meter is acting just like a volt meter would with an alternator.

Coby described very well how an amp meter works.

 

[Roadworthy]

I don't know how your ammeter is wired into the circuit. They measure current flow. If the alternator or generator is putting current into the battery the needle will deflect and tell you the rate at which it's doing so. If you turn on the light the alternator must put out more current to keep the battery charged. If you turn on so many accessories the alternator can't keep up your battery will begin to discharge and the ammeter will deflect in the opposite direction. That's pretty much the way an "idiot light" works, it just gives a bit more information.

 

[Richard]

Is correct operation meter on the right while machines and lights are running or should dial be on the left?

 

[ovrszd]

Is correct operation meter on the right while machines and lights are running or should dial be on the left?

Right is positive, left is negative. Amp meter or volt meter.

 

[WranglerX]

As ammeter measure all current flow in system... IF it is showing a plus (+) with engine running it shows that generator/alternator is putting out enough amperage to supply all the electrical needs ( battery charging- lights- radio - etc ...IF it shows a minus(-) with engine running it means generator/alternator can not supply enough amperage that electrical system needs or with engine off you have a power drain (left the lights on?)....

Ammeters in modern vehicles have gone by the wayside and now use a voltmeter that will give instant annalist of how how electrical system is and much easier to wire than ammeter...

The is sketch applies to a simple wiring system for a Volkswagen dune buggy, BUT it demonstrated how each indicator (ammeter VS volt meter) is wired...

Black lines are actually wiring ... Red and blue lines show actual current flow with ammeter...

Dale

 

[RickB]

Right is positive, left is negative. Amp meter or volt meter.

A typical volt meter indicates zero and positive values. A negative voltage value would indicate reverse polarity, not a discharge condition.

 

[rScotty]

Richard, you want to be careful here. There are several answers that are wrong - but I don't see any advice in the messages that will hurt you or the tractor.
Just like in politics, don't believe every explanations....

Tell me what happens with the ammeter when the key is on, the motor is NOT running, and the lights are on?

What I'm saying is do this: With the key on, and motor not running, turn on the lights. If everything is wired correctly then that's when the meter should swing to the left.
Assuming that your polarity is correct, then when the arrow swings to the left of zero that simply tells you that the battery is discharging. When the ammeter is to the right of zero then the alternator is doing its job of charging the battery.

Now if you wired it so that the polarity of the meter is backwards the meter will still work, it is just reversed. So in that case discharging is to the right, and charging to the left. That's all... the system is still working fine it's just that the meter reads backwards.

When the meter moves to the right of zero means that the battery is being charged. The farther it is from zero, the greater the charge or discharge it is measuring.

In a good charging system with motor running and lights on, the meter will still be to the right of zero. It will only move to the left of zero when the motor stops and the lights are still on.

Whether it is a generator or alternator system doesn't make any difference to the ammeter. Either system can also use a voltmeter to gain additional information as to how it is operating.

rScotty