81 CB 650-Not Charging Battery

Well Now that I finally got the bike started after replacing the
starter selenoid..........There is no juice going into the battery.
A wire may have come loose after re-installing the fairing, as the
wire bundles were moved a bit, but where do I start on this. I have
put my voltage Ohm meter to 15v mode while bike is running and have 11
volts showing across the battery posts at 4000rpm.
I suppose that it is probably the brushes inside the alternator, but
the bike only has 48,00km, or it could be the rectifier.
Are there any fuses related to this charging system?
Any ideas what I can do to get a better idea what the problemo is?
Thanks in Advance!
Tim.C

 

Look for loose connections, melted plastic connectors. If you find
melted plastic connectors, don't bother hassling with buying new
connectors, just cut the old ones off and solder the wires directly
together with plastic sleeving to insulate the solder joints...

I was trained by my rich uncle Sam to maintain the electrical systems
on his weapons of mass destruction...

One of the least obvious possibilities is that the alternator rotor
doesn't turn when the engine is running because the bolt that holds it
onto the end of the crankshaft has gotten loose or the tapered end of
the crankshaft that the rotor rides on has worn out. I have actually
had the latter problem, and had to replace the rotor...

Another possibility often overlooked is whether the engine is properly
grounded to the frame. If it starts by the electric starter, then the
engine grounding is probably OK...

But, what about the voltage regulator? Does it have a separate
grounding wire that runs to a sheetmetal bracket bolted to the frame?
Is whatever part the voltage regulator is bolted to properly grounded
to the frame?

Or is the regulator case properly grounded to a bracket that is
properly grounded to the frame? Everything has to be grounded together,
and the resistance between parts and the frame cannot be as high as 1
ohm, the resistance has to be in the milliohms...

What voltage reading do you see at 5000 to 6000 RPM? 4000 RPM is a bit
low for testing the alternator output...

but the bike only has 48,00km, or it could be

So check the brush length and check the diodes in the regulator by
hooking your ohmmeter across each of the three AC leads coming from the
rectifier and the red lead coming from the rectifier.

(If the rectifier doesn't have extrenal wires, but has a plug on the
side, you'll have to figure out which are the AC pins and which are the
DC pins on the rectifier from the color codes on the wires going to the
unit...)

If you don't get any reading, reverse your leads and check from each AC
lead to the red wire. You should get the same reading on all three AC
leads...

Then reverse the ohmmeter leads and check each AC lead to the
rectifier's black wire (or to the rectifier case. Again, you should get
the same reading. If you don't get a reading on one AC lead, the diode
is blown out and the unit is toast...

Then there is the stator. If it's a 3-phase stator (schematic shows 3
windings arranged in a "Y" configuration, check from phase to phase to
phase. All three phases will have the same reading, and none of the
phases should be grounded...

If the brushes are still within the specifications in your manual,
check to see if you have continuity between the two brushes with the
engine not running and the alternator disconnected from the wiring
harness. An alternator rotor should have about 1 ohm of resistance
across the slip rings and the resistance reading to ground should be
close to infinity...

One of the brushes probably gets power from the regulator, the other
brush is probably grounded. You should get some amount of battery
voltage on one of the brushes when the engine is running...

There usually are no fuses in a charging system, but gawd only knows
what tricks Honda might have incorporated in the system. Check your
manual's electrical schematic...

 

Check out http://www.electrexusa.com/electrex_fault_finding.html for a
really good charging system troubleshooting chart.

Carl