12 volt Alt charging volts

P-2 is the internal alternator's voltage regulator's "sense" line and tells the alternator guttz how much charge to feed to the battery from the BIG BATT STUD. P-2 is normally connected directly to the alternator's BIG STUD output. P-2 is the r/h terminal.

P-1 is the switched "excite" line and should be connected to the ignition switch THRU the idiot-lite.

Wired in the correct way, the Delco 10-SI alternator will charge at a slooowww 600 rpms, just above idle rpms..... ....Dell, a 12 volt advocate for the right reason

Ramrod

Also.. try bypassing the lamp for a second to give it full batt power on p1 for an instant and see if it's charge voltage jumps up. If so, your lamp may not be allowing it to excite enough ( though it should ) Might be a finacky or flaky VR module.

If the bulb is the culpret.. install a momentary 'tickle' switch instead.. like a horn button. A single push and the alt will be energized .. just got to do it every time you restart. Also.. you could simply install an appropriatly sized diode(s) in line with it. Radio shack sells some large diodes and epoxy packed rectifiers that ar good for 3-6 amps. A 6a would be nice.. or a pair of 3's . Install with the cathode 'facing' p1. It's automagic then.. just like your lamp was/should be.

Any chance your battery is marginal? bad contacts? What's the ammeter show?

Soundguy

SO... not enough current through lamp = NO charge at all, NOT a weak charge.

Jomama, are you having a problem with the battery not being charged enough?

What are you checking the charging voltage on your tractor with... an accurate hand-held meter, or a voltmeter installed on the tractor? My first thought would be a discrepancy between the meter at the shop and the meter you are using.

If that is not the case, and your battery actually is not being charged, I would check the alternator pulley to see if the belt is bottoming in the pulley and slipping, or if the belt is loose or glazed. It's true the alternator MAY not run fast enough at idle to charge well, but it certainly should when you rev it up.

Things to check... Is the alternator grounded? It almost certainly is, but if for some reason the brackets are rusted, or coated with a heavy coat of paint, it is POSSIBLE to have a ground problem.

Is there good continuity from the large output stud on the alternator through the wiring, clear back to the battery? Any poor connection in that circuit will "play with the regulator's mind".

Do you have the #2 terminal on the regulator jumpered to the large output stud on the alternator or ar you using remote voltage sensing?

In either case, measure the voltage right at the #2 terminal and see how it compares to battery voltage.

Do you have another battery you could substitute, and see if the charging voltage changes?

That's my point... I was trying to get him to check to see if the alternator was putting out at all. A reading of 13v could be battery voltage and points noise. I.E. a non-excited alternator due to too much resistance in the exciter line. I've seen those conversions done where someone used a ridiculesly sized bulb ( too many watts )as an ignition isolator.. and the alt would never excite. Threshold on the VR never got triggered. Course.. it could be a bad component in the VR module as well.. heck.. could be a badly coroded lamp terminal or p1 spade plug. There was enough paint on my 2n's p1 spade terminal that it would not charge when i first got it. For temp purposes a fingernail file fixed it..

Soundguy

I hate to be picky but that does not make sense.
"Too many watts" would imply a low resistance bulb. All that would do is let your alternattor back feed your ignition and you would have trouble turning off yur tractor. You can use a direct wire jumper to excite your alternator with a push button isolation.

ITYM you used a too small bulb (not enuf watts)
and could not excite yur alternator.

(Remember I=E/R or current equals Voltage over resistance.)

Roger

I got him a little excited with my previous post!

In any case.. the lamp was not letting enough current thru to excite the alternator. As A test I dropped in a 1 ohm ceramic resistor and it worked like a charm for troubleshooting.

Soundguy

I tore the alternator apart, it looked good and the parts checked out, I reassembled it with a new regulator just for luck, and just as I finshed assembling it, I realized from looking at the pulley that the Poly-V belt was bottoming in the grooves, and slipping, just like a worn V-belt does. That's one of the few times I've seen a Poly-V belt the looked good, no cracks, etc., but worn enough to slip!