Amp meter hookup issue

[pokitisme]

Got an issue hooking up a new amp meter. The person had the wiring all messed up on the Farmall h tractor. So I've got a YouTube video here. Please take a look and give me some advice

https://youtu.be/VwgO6Z7TBVY?si=iET9tqjLpvlJ3H_P

[Jim Becker]

Ammeter should move towards discharge when you turn the switch on. You need to swap the wires on the ammeter to the opposite terminal. Ammeter shows the same "charge rate" (actually discharging) with the engine running as not running with the switch on. Charging system is either not completely connected or not working.

[pokitisme]

And you're saying that the alternator might not be charging. I took it to one O'Reilly Automotive they tested it and said it was perfectly fine. But if I'm understanding you correctly there might be an alternator issue. It is a one wire alternator. And I only have the single wire coming off of it

What I really need to know is what wire goes where. I have the wire coming from the positive terminal of the battery. Should that go to the negative or positive of the amp meter.

Where does the wire from the alternator and from the coil go. If I know those two sets of wires I can figure out the rest myself

[MiCarl]

When wired correctly the ammeter will show current in/out of the battery. Yours is wired correctly backward since it shows the battery is charging with the tractor NOT running. Once the tractor is running all the power for ignition and accessories is provided by the alternator, not the battery.

When you turn the switch on the ammeter will only show discharge if the points are closed. If the engine happens to stop with them open the ammeter won't read anything when you switch on. On my H the engine generally seems to stop with the points closed. The ignition system on my H is in good condition. If the point gap were incorrect or the timing off it might not tend to stop with the points closed.

My H has a 1 wire alternator. If I were to start it as in your video it won't charge at all, it needs the engine to first be revved up a bit so the alternator excites itself. If i immediately throttle down it shows very little charge as yours does. I need to run it at about half throttle for the gauge to read 5+ amps. As the battery comes up to full charge the ammeter drops close to 0 regardless of engine speed.

It's not a volt meter, it will read 0 if the electrical system is in balance. It'll read (-) if you're discharging the battery and (+) if the tractor is charging the battery. If you've got the battery hooked to some external charger or boost box the gauge might pretty much read 0 when the tractor is running since your external device is keeping the battery topped off.

As an aside: The crankshaft pulley on an H is small and the maximum engine RPM is about 1800. You cannot expect the alternator to do much unless the engine is cranked up.

When the battery on my H died I could boost the tractor and the gauge stayed low even with the engine running fast.

I'd try throttling the engine up and see if the gauge moves up. If not I'd throw a volt meter on the battery and see what it read at full throttle. If it's 13 volts or higher the charging system is working fine.

[Jim Becker]

Move the wire from the battery to the opposite side of the ammeter. Connect the other two wires to the other ammeter lug.

[MiCarl]

Ok after reading Jim's post I looked at the video again. Your ammeter is connected backward - wire it as Jim says.

Once it's wired correctly it'll be just like my H. Show a minor discharge when switched on and stay that way after starting the tractor. On mine it'll show charging once I throttle up enough to excite the alternator.

[pokitisme]

Yeah thanks guys I haven't had a running amp meter on any Farmall H that I've had. And I know it's spelled in correctly I'm using speech to text LOL. And yeah I understood that part and had researched about it having to be throttled up to actually start showing a charge. I have had it hooked up with the old amp meter and the battery was being charged and going up but when I disconnect the negative terminal on the battery it will kill the tractor that's why I'm confused. But yeah I'm going to take Jim's advice and get on that tomorrow