One wire altenator question

bubbanm

Member
OK I have a MF150 that had been sitting in a barn for a long time and I am trying to get it to charge the battery. I purchased a one wire altenator and I was told I
could run a wire from the post on the altenator to the positive battery terminal. I did that with a 12 guage wire but my battery still is not charged after running the
tractor for a while. None of my guages work so I cant go by them. Could something be running my battery down? Or have I wired it wrong? The motor is in great shape but
the old wiring is not so great. The battery and altenator are new. One thing I have noticed is the the belt is not real tight but i have adjusted it as far as it will go
with a Freeman loader on the front . The altenator is adjusted out until it hits the loader frame.
 
Get you a volt meter, and put it on the battery. The battery should have 12-12.7 volts when its running it should show around 14 volts because of the alternator.
 
I have installed 3 one-wire alternators on different rigs. They don't seem to kick in until about mid-RPM, so I'd say you need a shorter belt so you can run it tight. You can run the one wire to the ammeter, and then from the ammeter to the battery. If the ammeter reads backwards, reverse the wires. Also, the one-wire alternator will drain your battery if you leave the rig unused for a week or two. I got around that by installing a Hobbs pressure switch in the oil pressure gauge line, and connecting the one-wire through that switch. The one-wire circuit only kicks in when the engine is running. All 3 of mine, two 6-volt and one 12-volt, work great, and one is nearly 15 years old.
a235989.jpg

a235992.jpg
 
On the single wire alternator you have to rev the engine a little, about to 1200 rpms or so, so it will "excite" the regulator so it will start charging.
 
If you read the paper work that should have come with the alternator on many it says to self excite it takes 2000RPM or more and that is hard to come by on most tractors. I use the 3 wire ones that excite the moment you turn the key on and they start charging at a low RPM unless there is something wrong with them
 
A local guru came up with a fiddle that allowed the alternators (Delco) to cut in at low revs - just above idle. Calls it a low-speed cut-in. I never did find out what the mod was.

There is some leakage current at rest - a few milliamps, which will run the battery down over a period of months.

And he showed me a trick to tell whether or not they're charging - if they're working a hacksaw blade will stick to the cap at the end of the shaft opposite to the pulley.
 

We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today.

Back
Top