12v conversion problems

Then...went to start my '52 8n up and do a little yard work..no juice..none..brand new battery stone cold dead..

The tractor was converted prior to me buying it. It has a GM alternator on it. The one with the 2 wire plug on the side and the single pole on the back. I compared it to my chevy truck and think I know the problem. The pole on the back of the alternator goes to the same side of the solenoid as the battery (right ??) then the plug on the side has 2 wires, one red , one white. the Red (The thicker of the 2) goes to the hot side of the ignition switch (On/Off)...on the truck the other side show continuity (OHMS) to ground...should this be the same on the tractor ???? the red wire leading to the on/off switch had a socket with a GM dash light bulb in it. I assumed (UT OH) that the light was there simply to indicate the the alternator was charging...is this correct...so synopsis:

Pole on back of ALT. to hot (battery) side of solenoid

Red (Thick) wire off of plug (Side of ALT) to switched (hot when switch is on)side of on/off switch

White wire off of plug on side of ALT to ground..

Corrrect ???

Sorry for length...

Tommy

I know of 7 ways to convert to 12 volts, some of them work better than others (grin).

While I usually recommend the "idiot light" scheme on 12 volt conversions, its got its problems as you have found out. The idiot light/marker light "decouples" or reduces the available power to the ignition coil so it won't sustain hot enought sparkies to keep the engine running and then the engine dies when you turn off the ignition key.

I like the 3-wire 12 volt conversion, because it causes the alternator to charge at the low RPM's that our N's run at. I don't like the 1-wire conversion, while quite popular for a lot of 12 volt conversions, it doesn't charge well at low tractor RPM's.

Somehow, I don't think your description matches the usual 12 volt Delco SI-10 conversion scheme. I don't think your white wire should go to ground. The Red wire usually has an "idiot light" in line to the ignition switch "on" terminal.

Usually pin 2 (remote sense) white wire is hardwired right at the alternator to the big battery charge stud which is usually hardwired to the battery stud on the starter solenoid for convience. The #1 (excite) red wire usually has the idiot light in it to the ignition switch "on" terminal which also goes to the ignition coil. And naturally, your 12 volt battery is negative grounded.

Starter doesn't care positive or negative ground. Alternator does care, the internal "diodes" absolutely require negative ground or else they turn into expensive semi-conductor fuses.

Ammeter semi-cares positive ground/negative ground. If it shows negative when you know the alternator is charging the battery, just reverse the ammeter connectons. Traditionally, ammeter show "+" when battery is being charged and traditionally "+" is to the right of the meter scale..... ..... ...HTH, Dell

Twelve volt generators? Alternators with seperate regulators?

Six volt coils? Twelve volt coils with dropping resistors? Twelve volt coils that run at twelve volts?

Heck, I haven't stopped to make a list.

Part of the joy of twelve volt conversions is there are so many ways to do it. Some of them even work.

Your mileage may vary

The wire you're thinking of connecting to ground should go to the battery -- it senses the voltage at the battery. Tieing it to the BAT post on the back of the alternator is good enough.

The heavy red wire with the bulb supplies the excitation to the alternator to make it start up. The bulb provides a visual indication that as to whether or not the alternator is charging. It also prevents the alternator from feeding the ignition system when you turn off the key switch.

Charge up the battery and then turn the key on. Does the bulb light up? If not, something is wrong in that circuit (either the wiring, socket/bulb or alternator).

If the bulb lights, start the tractor. Does the bulb go out? If yes, the alternator is charging - you can verify this by measuring the voltage at the battery (it should higher than it was without the tractor running). If not, the alternator may have problems or the bulb may not allow sufficient current to start the alternator.

If the bulb stays on, try momentarily jumping across the bulb with a piece of wire -- if the bulb doesn't come back on when you remove the wire, the bulb is likely the culprit (it's not letting enough current pass to excite the alternator).