How do I test a regulator?

   / How do I test a regulator? #1  
gt14

gt14

Silver Member
Joined
Jul 19, 2005
Messages
163
Location
Aumsville Oregon
Tractor
Yanmar YM146 YM165D
Does anyone know of a way to test a regulator? My tractor used a generator/regulator setup. Now I what to know if the regulator is good or bad.
 
   / How do I test a regulator? #2  
gt14 said:
Does anyone know of a way to test a regulator? My tractor used a generator/regulator setup. Now I what to know if the regulator is good or bad.
Click to expand...

To test a regulator, measure the voltage on the battery with the tractor off. Now start the tractor, and measure the voltage at the battery. Charge voltage should be around 14 volts. You need a voltage meter of course.

If your tractor is a 6 volt system, the charging voltage should be around 8 volts.
 
   / How do I test a regulator? #3  
J_J said:
To test a regulator, measure the voltage on the battery with the tractor off. Now start the tractor, and measure the voltage at the battery. Charge voltage should be around 14 volts. You need a voltage meter of course.

If your tractor is a 6 volt system, the charging voltage should be around 8 volts.
Click to expand...
The problem with this is that you are not really testing the voltage regulator, you are testing the output of the alternator. If you measure at the battery and it's only 11 or 12 volts, then that does not mean the regulator is bad, that means the alternator is.

The voltage regulator does just that, it regulates the voltage sent to the battery. If a voltage regulator is bad, then the power sent to the battery will be jumpy and erratic.

What I do is put a voltmeter on the battery terminals with the car idling and it should read about 12-13 volts, then have someone slowly raise the idle of the engine and you should see the volts raise to about 14-15 volts. If it goes above 16 volts or does not hold a steady reading at a steady engine speed then the regulator is gone or going. If the reading never goes much above 12 volts, then the alternator is on it's way out.
 
   / How do I test a regulator? #4  
A generator has 3 connections that connect to the regulator, the field, armature and ground. The original regulators for these are almost always
mechanical. A generator has a polarized output and if you measure it's output, it will be the full voltage as the regulator is down line from it. Generators don't charge very well below the speed it was designed to operate at because they don't put out enough current, not voltage. The voltage is largely fixed by the number of windings. The voltage rectification is made by a split ring commutator and brushes. As the name implies, there is a split in the ring of the armature. This is kind of rough on the brushes.

Alternators produce their output on the larger fixed windings instead of the moving ones on a generator. They can be internally regulated or externally regulated. They also have a smooth commutator so the brushes have an easier time. Rectification is by diodes as well. It also can produce a charge current at idle. The regulator controls field current which changes the output voltage.

What model do you have? There are some ways to convert to an alternator that are cheaper than getting new generator equipment. I have a 2000BD with a Datsun 510 alternator and regulator that bolted right in without mods.

Jerry
 
   / How do I test a regulator? #5  
FL_Jerry said:
What model do you have? There are some ways to convert to an alternator that are cheaper than getting new generator equipment. I have a 2000BD with a Datsun 510 alternator and regulator that bolted right in without mods.
Click to expand...
Apparently in the early 70's Yanmar and Datsun applied the same family of Hitachi gear on some machines.

Datsun (through 1973) regulator is identical to Yanmar 2000's per testing it at AutoZone - plug and all. Datsun used that regulator to control a 35 amp alternator that is a direct replacement for the 15 amp unit on the Yanmars. Note this interchange is only YM1700, YM2000 (through YM2000B) and the US equivalents (YM195, YM240) so far as I've seen posted here.

Also the 50 amp Hitachi alternator (Datsun w/AC) is a near match using the same mount and electrical connections, but it's fatter so it might need a longer belt and adjusting strap.

I would like to hear if there are similar equivalents for other Yanmar models.
 
   / How do I test a regulator? #6  
gt14, refresh my failing memory. Didn't you recently replace the stk setup with a automotive alt and possible one with a built-in reg? If so, are you having problems with the swap?
 
   / How do I test a regulator? #7  
Dmace said:
The problem with this is that you are not really testing the voltage regulator, you are testing the output of the alternator. If you measure at the battery and it's only 11 or 12 volts, then that does not mean the regulator is bad, that means the alternator is.

The voltage regulator does just that, it regulates the voltage sent to the battery. If a voltage regulator is bad, then the power sent to the battery will be jumpy and erratic.

What I do is put a voltmeter on the battery terminals with the car idling and it should read about 12-13 volts, then have someone slowly raise the idle of the engine and you should see the volts raise to about 14-15 volts. If it goes above 16 volts or does not hold a steady reading at a steady engine speed then the regulator is gone or going. If the reading never goes much above 12 volts, then the alternator is on it's way out.
Click to expand...

I believe he said he had a generator not alternator. I would replace the generator with a one wire alternator. I replaced my generator with one of these, and it works great. The starter is still 6 volts.
 
   / How do I test a regulator? #8  
J_J said:
I believe he said he had a generator not alternator. I would replace the generator with a one wire alternator. I replaced my generator with one of these, and it works great. The starter is still 6 volts.
Click to expand...
Yeah. It seems like a 12 volt conversion driving a 6 volt starter would burn it up but actually the starter's internal windings are twice as heavy as needed, so all that happens is it cranks twice as fast. I think overall the life of the starter is about the same as it would have been using 6 volts. BTDT - on a 54 Willys Wagon with Studebaker 259 V8, the only engine that dropped into those and bolted up without adapters. It started real good!
 
   / How do I test a regulator? #9  
J_J said:
To test a regulator, measure the voltage on the battery with the tractor off. Now start the tractor, and measure the voltage at the battery. Charge voltage should be around 14 volts. You need a voltage meter of course.

If your tractor is a 6 volt system, the charging voltage should be around 8 volts.
Click to expand...

J_J has it right. In addition, I rev. the engine up to operating RPMs, and turn on some load (your lights). The battery voltage should still be arouind 14 volts. This also test the alternator. There are failure modes of the alternator that will allow it to still work, but not put out as much current as its rating. Check your belt for slippage too. With the enginr off, grasp the pulley and see if you can turn it by hand. Generally you should not be able to or it should be very difficult.

What symptoms are you seeing?
 
   / How do I test a regulator?
  • Thread Starter
#10  
Yes I did replace my generator with a alternator setup that is working great. I had my generator tested and it worked prefectly. But before I converted to the alternator I bought my third regulator. I was just curious to see if these very expensive regulators where the bad part of my charging system of did I have another problem. I would like to know if I can test the resistance between the wires on my regulator. My regulator is a 6 prong one. PN 121520-77710 called a current limiter.
 
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