12 Volt Battery Alternator

The laptop is WARM, though, after the hot posts all day, and makes a good lap and finger warmer!

However, a tractor is a missapplication for most people because extended idling of a tractor engine at 450-500 rpm is frequently standard operating procedure. Especially with the first gear ratio in these old Fords.

I think we need to get together around a WARM stove and "talk shop" over a few brewskies!

Problem is I can't drink, for health reasons!

Have good one, and let's "agree to disagree"!

I THINK I have a FAIR undertanding of alternators, even the "goofy" one-wire units.

I sell and repair alternators. The one-wire units cause BY FAR the most grief and complaints, when folks are unsatisfied with the RPM's needed to "excite" them.

So I wised up and sell and use the "stock" 3-wire units, and eliminate those complaints and problems problems.

If the "one-wire" idea is so GREAT, and CHEAP, why weren't the alternators made that way from the OEM, when the corporate "bean counters" cut every uneeded circuit, wire, and frill, and cheapen things up as much as possible, yet they produced the 3-wire setups?

It is aftermarket parts suppliers who have come up with the "10SI-style" one-wire alternators, they are NOT OEM.

I could just as well turn your statement around, and say "why don't YOU use things YOU don't understand (3-wire alternators), and WHY should YOUR method (the one-wire alternator) be everyone's preferred method, any more than mine?

Use what makes YOU happy, but why steer others into lesser-performing setups?

>>Unless the internal regulator is defective or a diode INSIDE the alternator is shorted or leaky<<

Yep, I should have stated that. But leaky diodes are quite possible.

If it is a standard "3-wire" alternator, and it's wired correctly, very likely there are internal problems in the alternator.

If it IS a standard "3-wire" alternator, with the engine shut down, and the switch "OFF", the number 1 terminal should be at ZERO Volts, and the #2 terminal should be at BATTERY VOLTAGE.

Assuming it's wired correctly, disconnect ALL wires to the alternator, and see if the battery still "dies" over time.

If the battery holds charge, with the alternator disconected, you have narrowed down the problem the the alternator.

If the battery still loses charge, with the alternator out of the circuit, you may have a bad battery, or a partial short somewhere that is bleeding off battery power.

If you shut off your tractor and the points happen to stay open, you'll probably be able to read a voltage from the P1 terminal on the alternator to ground. So, when the points happen to stop in the closed position, that voltage is causing a current flow to ground (through the coil primary and points and to ground).

What you need is a small diode in that circuit to prevent this current flow when the points happen to stop in the closed position. Do a search for "diode" in the archives here and it will be mentioned numerous times.

Sorry, but the diode in the wire to the alternator's #1 (switched excite) terminal only prevents the backfeeding of current to the ignition system while the engine is running, allowing the engine to shut down when the switch is turned to the "OFF" position.

Once the engine is stopped, with the key in the "OFF" position, the absence or presence of the diode has NO EFFECT on draining the battery.

Current DOESN'T backfeed out of the alternator's #1 terminal once it's shut down, and not charging. (Unless the internal regulator is defective or a diode INSIDE the alternator is shorted or leaky.