Need Help Interpreting What I See on the Amp Meter

I have a Farmall 450 that is new to me. I recently have been having issues with the battery going dead. The last time this happened it sat for less than 24 hours and the battery was flat as a pancake.

My Amp meter was non functional so I replaced it with a new one from the dealer. On start I noticed that it never registered a charge.

This tractor is 12v positive ground and still has the original generator. I took a look at the regulator and gave it about a 90% chance of being the problem. It was all rusted and corroded and the contacts at the large coil were sticking. My new amp meter confirmed this as it registered 60 Amps of discharge.

Now for my question. Once I replaced the voltage regulator and started it back up the amp meter registered a large amount of charge happening. >+40 amps. After about 5 minutes the meter started showing a slight discharge. (About the same you see with key on, engine stopped.) The meter never registers anything other than this slight discharge for the entire time of operation.

At next start, I will see the large charging activity again and this lasts 5-10 minutes. The charging amperage will vary with engine speed. At some point, all charge activity stops and all I see is the slight discharge.

Is this normal?

Thanks in advance.

Not normal.

You should see a fairly large charge at first to replenish the battery from cranking the engine, then a slight CHARGE the rest of the time.

Slight DIScharge means that the charging system is not working.

(quoted from post at 21:21:57 09/18/21) Not normal.

You should see a fairly large charge at first to replenish the battery from cranking the engine, then a slight CHARGE the rest of the time.

Slight DIScharge means that the charging system is not working.

Click to expand...

Kinda what I was expecting to hear. Thanks for the reply. I will get the generator gone through next and take a good look at the wiring. The insulation on many of the wires is real brittle with age and flaking off in spots. Could also be contributing to the problem.

Battery charging voltage is the important diagnosis. Using a meter with a needle that moves, or a really good digital meter test
directly across the battery posts (not the terminal clamps). A charged 12v battery, with the engine stopped, will register 12.6
volts or a tiny bit more if it was fresh off of charging. If the tractor is running at 3/4 throttle, it should be putting between
14.2 and 14.6 volts into the battery. If not charging, it will read the same as the original battery voltage. Amp meters can be
somewhat off at low amp conditions. It should taper off over 1/2 hour to near ) on the gauge. Jim

It may be time to put on one of those small alternators ?

(quoted from post at 22:32:13 09/18/21) . . . Amp meters can be somewhat off at low amp conditions. . . .

Click to expand...

irst thing to check is where ZERO really is on your ammeter. It usually isn't exactly at the zero mark on the face. Shut everything off (unhook the battery to be sure). Then look at the ammeter. The needle will be pointing at ZERO.

All of the ammeters here on the farm point at zero for all intents and purposes when there is no load or charge on the electrical system. In my experience it is rare for them to be off much, less than the width of the line. Just the coil being energized moves the needle enough that there is "air space" between zero and where the needle is pointing.

It seems as if I may be worrying about nothing. After using the tractor about 10 hours the battery is showing full charge at 12.6 volts.

I still think the indication is confusing but at least I know what 'normal' looks like.

This new meter is dead center on 0 with battery unhooked. I did check that out when I installed it so I would know my starting point. Definitely a point to be aware of.