Alternator / Regulator woes

[tab1324]

Last night I reviewed the following in the repair section under Electrical, charging / tach problems...

The resistance between the brown and green wires should be 3.5 ohms +/- 10%. These are the wires that go to the field coil of the alternator. The brown wire carries current from the battery and the green wire goes to the voltage regulator.

With the connectors back together turn the ignition on and you should measure about 12 volts between the brown wire and the bike frame and it should be less than 1.8 volts on the green wire.

Then start the bike and as you rev the engine the green voltage should go up to 9~11 volts if the regulator is working properly. If you measure battery volts on the green wire with the ignition on and engine not running then the regulator is not working and the alternator will not put out any current.

I tried this test and got less than 1.8 volts with bike not running. Actually I got about 0.5 volts. Then when I started bike I got about 5.5 volts. As I revved the motor, I got less and less voltage. Is this indicating a bad field coil or a bad regulator / both or neither???? I'm totally confused.

Thanks,

Tom B.

[freebird01752]

Tom,

I am going through the same nightmare that you are.

Check out the thread "Charging Question" and see if that makes more senses.

Steve

[tab1324]

Steve,

Let's keep in touch on this... I've got no more ideas for mine... sounds like you're in the same boat. I haven't gone wild on the connections yet, all I've done is taken them apart, inspected them and blew them out, and put them back together. Everything looked pretty good if you ask me.

Sounds like yours is doing some funky stuff too. When I revved mine and the tach came alive, the warning light started to blink slowly and all the instruments started cycling (excuse the pun). Brakes, battery, etc...

Don't know if you read my other threads today but my bike is actually loosing voltage at the regulator when it is revved. According to specs it should gain voltage. Maybe something in mine is hooked up backwards????????????????????????????

Good luck!

Tom B.

[randy]

Tom,

Your voltage is dropping when you rev because you're not charging. When you rev, you're asking the engine to do more work for which it needs more current. Without the charging circuit working, all of the current needs are drawn direct from the battery, draining it. Make sense?

Now, about your alternator / regulator test. What you were describing in your post was exciting the field coil direct from the battery. This is how the system works.

The alternator rotor, that big metal slug bolted to the end of the crankshaft is magnetized by the field coil. This spinning magnet then induces a voltage in the stator, that outer coil of wire.

The regulator, just as it's named, regulates the voltage to the field coil, thereby changing the magnetic strength of the rotor, ergo the voltage induced in the stator.

First, do a continuity check on both the field coil and the stator coils. Assuming you get good readings on them, reconnect the stator plug and proceed to the running test.

Connect a volt meter to the battery terminals. you should read 12 - 13 volts, less, give it a slow charge. Assuming you have ok battery voltage, leave the meter connected for the test

Connect one (either one) lead of the field coil to the chassis. Start the engine. BRIEFLY touch the other lead to the positive battery post. Don't leave the field coil connected this way or the higher voltage can eventually fry bulbs and worst case, your TCI box. The meter should read at least 14 volts. If you get the rise in voltage, this proves that the field coil, stator coils and rectifier are working and the regulator is toast. Unfortunately for us, our rectifier and regulator are in one box. If you get no voltage change at all, the rectifier is not working. If you've checked and cleaned all of your connections, and the problem still persists, swap the rectifier/regulator.

I hope I've been clear on this, but if not, repost your questions and I'll try to help.

Randy

[freebird01752]

Randy,

If there is no change where does that point to?? Recifier? feild coil? regulator? stator? battery?

I did the test and I get the right values from the field coils. Green wire is 1.08 volts, brown wire is 11.97 volts with the switch on. Start the bike and no change. Continuity checks out on both the stator and field coils.

Thanks,

Steve

[randy]

From what you've told me, the rectifier is bad. That assumes that all of your connections are clean and tight. Remember, the rectifier / regulator are in one box, so for your purpose, it doesn't matter if it's the regulator or the rectifier that's bad, you have to change the whole thing.

Randy

[freebird01752]

Thanks Randy,

I was thinking reg but since they are both in the same box. I have ordered a brand new reg/rec.


Steve

[randy]

I said that the rectifier is the culprit because you claim you got the right voltage readings at the field coil. The regulator controls the feild coil, so if the voltages at the feild coil were reading correctly, then the regulator is doing it's job.

The rectifier takes the AC current generated by the stator and converts it from AC to DC, and if all is going well, that output voltage is a couple of volts above normal battery voltage at all times so the battery is never in a draining state.

Am I being clear on this? I hope so. Good luck with your problem and keep us posted.

Randy

[tab1324]

alternator test

An electronics guru friend of mine looked at the wiring diagram with me and suggested a test:

Attach a low voltage, low current battery (watch battery or triple A) to the field coil wires (green and brown) from the alternator. Start the bike and take an AC voltage reading from white wires to ground.

He said that this would prove whether the alternator is producing current and thus rule it out as a possible suspect.

I did the test and at idle I read 1.3 volts (voltage of the battery I was using when tested by itself). As I revved the engine the voltage increased to about 3.0 volts. So then I removed the battery and did the same test without it.... I got the same readings. Is his test bogus or am I getting stray voltage from somewhere maybe????

So confused....

Freebird - how are things on your end? I see you ordered a brand-new regulator. Let me know the results. Also, have you done the resistance tests accross the alternator wires? I tried this and I can't get a reading on either of my two alternator field coils.

Tom B.

[freebird01752]

Tom,

I have done so many test I can'y remenber if I did that and what the values were. I will check again in the morning and let you know.

The new reg/rec will be here Tuesday so I will let you all knoe the out come.


One other thing......... Is there anything in the electrical system that will cause the rectifier to be blown out. Really don't want to put the new one in and it get blown out by something else that I should have checked first.

Steve

[freebird01752]

Tom,

I went back to my thread and yes I did an ohms test on the stator wire and got 3.72 on all of them.

Hope that helps,

Steve

[newmaac]

Freebird, I have a few extra regulator/rectifiers, if you want to try swapping one out to see if that solves youe problem.
If interested, you can send a PM.

[randy]

Guys, the top three reasons that we blow out a regulator are:

3. a shorted field coil - I think you've ruled that out.

2. Trying to draw more juice than the system was designed for. The accessory fuse is rated at 20A. Don't try to draw any more.

AND, THE NUMBER ONE REASON REGULATORS BLOW IS:

1. LOOSE CONECTIONS

This one is tricky, because many think that a loose connection is just the absence of adequate voltage. It is that, but much more complicated.

The load, not having the correct voltage, will draw more current to compensate.

The extra current draw will cause the connections and all associated components to heat up, the heat creates additional resistance, causing the load to draw even more current.

The higher current draw then creates more heat and this destructive cycle continues until either the connection melts apart or the component fails.

In electronics we simplify this calling it thermal runaway. Solid state components are especially suseptable to damage in this way because they are very sensitive to heat. Look at your regulator / rectifier. See those fins? They are heat sinks. Keep them clean and free of obstructions. Also keep the mounting bolts tight. And the ground straps clean and tight.

HTH

Randy