Ammeter question....

[ovrszd]

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

Yep, I did a very poor job of describing what I meant....

Right is more, left is less in regards to a volt meter.

 

[Richard]

It sounds like you have the alternator and the battery on the correct sides of the ammeter.
Where are the lights and other such loads connected into? Those should be on the alternator side of the ammeter and it sounds almost like they're currently on the battery side of the ammeter.

Not making fun of what you said....but in a sense, I find it funny. I don't know what the lights/loads are connected to. The diagram said (making this up)

Plug wire:

41W into the back of alternator
948Z into headlights
WQ 14 into (ammeter)
63-B into (starter solenoid)

I'm fairly sure I can turn the lights on even with key turned off. I did this in warm weather where it gets dark late and I was curious how the six LED lights (2 in front and 2 on each fender) would light things up so I remember once while walking the dogs (in the dark) walking over and turning the headlights and then all lights on. I do NOT think I had to turn the key.

Since this thing is so tall and I was on the drivers side, I didn't look and couldn't have seen it anyway had I looked (without climbing) what the ammeter did.

I think my wife is leaving today to visit a couple estate sales.

If she does, I think I'm going to drag my batteries out there and get a conclusive answer to what happens (to the ammeter) with the key off.

Everything seems to work fine so I'm not bothered about that..... my main point of curiosity was that I'd never seen the meter in the negative and I expected to. However, if my presumptions on how it operated were faulty, then all could be fine and I've lost a couple stupid points with an education!!!

 

[ovrszd]

Let me change the subject slightly......

I have an ammeter. What if instead, it was a volt meter.

As a practical matter, what's the benefit of one over the other? (if any)

I prefer a volt meter for these reasons.

It indicates the health of my charging system by telling me the maintained voltage in the battery. I know whether my charging system is keeping up or not. An ammeter tells me that too but gives me no indication of battery condition.

A volt meter saves me in a failed charging system condition. It tells me what's "left" in my battery. All an ammeter tells me is the charging system has failed. No idea of battery condition. Battery voltage gives me an indication of how near system failure I am, i.e., when my vehicle is going to shut down. It also indicates whether I would be able to restart if I shut down the machine.

I'll always choose a volt meter. It's more critical to me to understand how much battery I have left. It's less critical to me to understand whether or not my charging system is working. After all, an ammeter can be showing a charging situation and my battery getting lower by the minute.

 

[DK35vince]

I prefer a volt meter also.
I can see the exact battery voltage when not running and the charging voltage when running.

 

[Richard]

Interesting stuff!

I can see where the volt meter would be of benefit..... actually, I think I was looking at the operation of the ammeter from the viewpoint of how the voltmeter would work as I've been looking at it as an indication of my batteries health/charge. Looks like instead, I was monitoring the charging systems health!!

Do they make a dual purpose gauge (same size) that does both?

 

[ovrszd]

Interesting stuff!

I can see where the volt meter would be of benefit..... actually, I think I was looking at the operation of the ammeter from the viewpoint of how the voltmeter would work as I've been looking at it as an indication of my batteries health/charge. Looks like instead, I was monitoring the charging systems health!!

Do they make a dual purpose gauge (same size) that does both?

Common misunderstanding.

I've never saw a gauge that does both but there's a lot I haven't saw.....

 

[Fuddy1952]

It's hard to understand electricity because you can't see it unless it's lightning. You can see water so it's easier to understand thinking of electricity as water.
Current is volume, voltage is pressure, resistance is a water valve, wires are pipes.
Your battery is supply (water tank). Anything needing lots of current needs a large wire (large pipe) like the starter motor. Volume.
Anything needing lots of voltage needs a small gauge wire (small pipe but thick wall) like a spark plug wire. Pressure.
Ohms Law is the relationship between voltage, current and resistance.
If the ammeter is wired correctly then engine not running (alt/gen not turning), anything you turn on, lights, etc., ammeter needle should move left (-- discharge). Engine running ammeter needle should move right (+ charge).
I would wire everything back stock the way it was. It's been that way nearly 50 years working fine. Back when that tractor was designed all you really cared about was engine running above idle ammeter shows charging. Running needle moving left discharge means a problem with alt/gen, regulator or wiring problems.
Meters on tractors like that years ago were better because at a glance even in bright sunlight you could see if everything was ok.

 

[ovrszd]

Great explanation Fuddy. I've often heard the water/electricity comparison and believe it to be valid.

I'd agree to put the tractor back like it's been since inception.

So,,, makes me wonder,,, why do they now use volt meters?

 

[aczlan]

Common misunderstanding.

I've never saw a gauge that does both but there's a lot I haven't saw.....

There are a lot of gauges there that read up to 10 amps on the ammeter, but not any (that I have seen) which read more than that as a combination gauge in the "standard" round form factor.

Aaron Z

 

[aczlan]

So,,, makes me wonder,,, why do they now use volt meters?

An ammeter will tell you if the battery is charging or discharging, but it will not tell you how charged the battery is, so if the battery has a bad cell and is at 11 volts after starting the tractor and continuously charges but never gets above 11.5 volts, everything will look good on the ammeter, but the battery may not start the tractor next time you go to use it.

Aaron Z