to35 alternator problem

ZangFarms

Member
I am working on a TO35 with an electrical problem that I cant seem to chase down. It has been converted to 12v with a 1 wire alternator. I am having trouble getting the tractor to charge. Battery is new, cables are new and the battery is grounded directly to the chassis, solenoid is new, alternator and all wiring is new. I am sure that the battery and alternator both have clean grounds. I had the alternator wired directly to the hot post on the solenoid and cannot get it to show a charge. all I get when I test with a voltmeter is a battery voltage reading. Anywhere within the entire system all I can find with the tractor running is battery voltage. I have been told as well that it sometimes works better to wire the alternator directly to the positive terminal on the battery so I tried that with the same results. I have also tried a different alternator and still cant get it to show a charge and I find it rather far fetched that I have two bad alternators. What am I missing? this tractor has me so frustrated I'm about to pull my hair out, this isn't a complicated system!
 

I recall reading some of these 1 wire GM alternators only start charging at 2000rpm, which your tractor may not be reaching at idle.
Rev it up to see if you have the 14.5v that starts to output.

Some guys also use a smaller pulley to give more RPM to the alternator.
 

I recall reading some of these 1 wire GM alternators only start charging at 2000rpm, which your tractor may not be reaching at idle.
Rev it up to see if you have the 14.5v that starts to output.

Some guys also use a smaller pulley to give more RPM to the alternator.
 
That GM 10-Si alternator might come to life at a higher RPM to excite it. Chances are you already revved it and no such luck.
You can install a different internal voltage regulator that will excite at a lower RPM. See the seller Triodiode on Ebay for that VR.
The other trick is to jumper the 1 wire genny from the bat post on the rear to the 'A'(?) terminal on the side. It's just a momentary connection to wake up the alt. You might hear the engine drop i RPM once the alt wakes up or you could hook up the meter and watch the reading. It should go from 12.6 bat voltage to 14.2 minimal. anything above 16 is too much and I believe 14.6/8 is about the usual range.
So get your self a 4 inch jumper wire and give it a try.
 
The alternator doesn't care if it's connected to the battery or the solenoid end of the cable. I prefer the solenoid end, as that gets the connection away from the corrosive battery.

The alternator need to have a #10 gauge wire. Just to be sure, check the voltage between the alternator case and the actual post on back of the alternator. Should have battery voltage there at all times.

Like others said, probably just not up to enough RPM to get it started.

It is possible to have gotten 2 defective alternators though, especially if the came from the same mfg. Bad parts, bad assembly are always a possibility. Just about any auto supply can test them for you.
 
Do as Bruce says and with engine running, momentarily jumper from hot battery output post at rear of alternator to #1 pin on edge plug. You may need to remove the cover plug on the terminals.

If this makes it charge you could connect a diode or lamp between ignition switch and #1 pin and it should charge as soon as engine is started
 

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