Troubleshooting charging system

It should be simple to figure out what has gone wrong, but questions keep poping up. First of all, I seem to have misplaced my fo-4 manual, so if you guys could please give me a quick rundown on where to put the test leads on the multimeter to on the genny, I would appreciate it!

Secondly, I had the genny rebuilt last year and replaced the voltage regulator as well as a complete rewire. All that seemed succesful, as I have had no problems until now.

I charged the battery and went out to hog the pasture tonight. It started getting dark so I turned on the lights. Five minutes later she started missing and the lights started getting dim (DUH!). I shut the lights off and limped back to "sick bay" in the dark. Before I shut it off, I measured the battery and had 6.02 volts at 1/2 throttle. When I turned the lights on, the voltage started dropping rapidly until I thought it was going to stall, and I turned the lights off, and the voltage jumped back up to 6 volts. Now here's where I start second guessing myself. I know the battery is the oldest component, so I am inclined to think it is just not holding a charge anymore, but wouldn't the reading at the battery be much higher with the tractor running regardless of a dead battery? I am thinking the genny output should be in the neighborhood of 7.5 volts or so, is that right? Sorry for the long post, I just wanted to give good details so you guys could have a better idea of what to suggest. As always, I really appreciate your taking the time to give some advise!

Rob

Starting voltage test:
Voltage across Bat while cranking should be a little less than 6v. If <5v change the battery. Voltage across the starter while cranking is less then Bat voltage. If more than 0.7v less then feel for a warm connection that will need cleaning.

On the vom.. if it is analog.. this works better.. or a high quality digital. The cheapy digitals don't do good for testing gennies.... but here goes.

With engine running.. test from armature to ground.. armature is the big charge stud on the genny. Remember that your system is positive ground.. so red/+ lead on VOM goes to the ground.. and black/- lead goes to the armature... this won't matter much to a digital VOM.. but WILL to an analog VOM.

when running.. you should see votlage on the armature.

Here's the deal.. look at your ammeter. When it is running.. it should show a charge.. sounds like yours is showing a discharge?? right?

Try shutting the machine down and then repolarizing the genny/vr. Jumper armature to battery (hot post )with a piece of wire. May spark a little. Crank her back up.. does the ammeter show charge now? (good). if not.. try full fielding the genny. Use your jumper wire to jumper from field tab to ground ( your genny should ahve both those tabs convieniently next to each other. Does charge show on the ammeter? (if yes, VR is bad ). If not.. use gator clip and jumper arm and batt at the vr, again check for charge at ammeter.. if yes, then vr cutout is not working.. if no.. leave that jumpered and then jumper field to ground.. if charge shows, then VR field control AND cutout are bad.. in either case.. replace vr. Post back if you have questions.

Soundguy

Unless your battery is very low.. I'd doubt that a problem like that is electrical.

To test it.. charge up your 6v battery full.. then test it. A charged 6v battery will run those engines all day long without a chargeing system.

More than likely it is a carb adjustment or carb cleaning problem.

When's the last time you cleaned the air breather? changed the points/plugs/wires/cap/rotor/condensor, etc.

Soundguy

Bottom line, 6yo battery would charge to 6.2v but when I hit the starter, the battery volts dropped to 4.2 volts. BAD CELL. New real 6v tractor battery from (byte my tongue) John Deere dealer.

Still wouldn't charge more than about 6.3v until I replaced the INTERNALLY CORRODED battery clamp to solenoid with new flexable 1/0 (thick as yer thumb) cable. Now my new battery charges at 7.4v and I haven't changed the squarecan voltage regulator.

Infact, I was so excited I forgot to "re-polarize" the V/R. 7.4 volts works for me..... ...Dell