Roddy Meatstick.............. wrote:
> Why is it that my lights dim a little when I rev up the motor from idle.
There are a number of possibilities why your lights would go dim as you
rev up the engine.
You might be "sinking" the alternator's battery charging current into
an old sulfated battery. When you "sink" current into a short circuit
or an overload, it turns into heat and the voltage applied to the
circuit drops dramatically, as you have noticed when your lights
dimmed.
Or, the battery might have a lot of lead particles in the bottom of the
cells, shorting the plates together. You can see the lead sludge if you
remove the battery and look up through the clear plastic case.
Old batteries that have been dehydrated may have bulges in the sides of
the case, or the battery may have the "starved horse" look, with ribs
sticking out and the sidewalls are curved inward.
Even maintenance free batteries will eventually lose their sealed-in
water and begin to bulge or look like a starving horse.
Your generator is a permanent magnet type. It has stationary copper
windings and a rotating magnet called a "rotor" attached to the
crankshaft. It's possible that the nut holding the rotor is loose and
the rotor isn't turning with the crankshaft.
One of the things that I was taught when I went to aircraft electrician
school in the Air Force was not to *ass*sume that the alternator was
turning just because the engine was running. If the alternator doesn't
turn with the engine, it cannot generate electricity.
Suzuki bolted the rotor on the tapered end of your expen$ive
crankshaft. But it still might not be turning when the engine is
running.
That would be bad news on your Intruder, which has a woodruff key
locating the rotor in one position. A broken woodruff key would chew up
the end of your crankshaft.
I had battery charging problems as you describe on my GS-1100. It
turned out that the alternator rotor was loose on the crankshaft, and
eventually the inner taper of the rotor wore so badly the rotor wasn't
turning as the crankshaft spun. The stub on the end of the crankshaft
got all chewed up and I will have to replace that part if I ever have
the crankshaft rebuilt or straightened.
Then there is the problem with poor quality crimped connectors and
mismatched electrical connectors in the charging system.
Suzuki and the rest of the manufacturers use crimped electrical
connections for speed in production and quick replacement of parts in
the $tealer$hip$.
Crimped connections are poor connections, compared to permanent
soldered connections. Many owners cut off the crimped connections when
they have problems with them and they solder the wires directly
together.
Suzuki and the rest of the manufacturers buy alternators and rectifier
regulators that have connectors that don't match, so they have to add a
little jumper pigtail between the alternator and the rectifier
regulator and the bike's wiring harness and that just adds more poor
quality connections to the system.
The poor quality connections heat up because they make poor cotact from
being loose or corroded. You may find that the plastic connector shell
is melted, or plastic sleeving used for insulation has turned black
from overheating.
You may notice that the wires coming from the alternator stator are
blackened for an inch or more back from the bullet connectors where
they attach to the motorcycle's wiring harness. It's time to cut off
those connectors and solder the wires directly together.
Don't overlook the possibility that your ignition switch is the
problem. If you run the engine for ten minutes and then feel the back
side of the ignition switch and it is too hot to touch, the ignition
switch needs to be replaced because it's making bad contact.
The rectifier regulator on your Intruder is a shunt type device. When
voltage rises above a certain voltage (usually around 14.5 to 15.0
volts) a zener diode will trigger a silicon control rectifier to ground
one of the three phases in the stator to ground for half a sine wave.
Then the SCR stops conducting until the next high voltage event, which
occurs as soon as the voltage on the next phase rises above the zener
set point.
This cuts power output from the three phase stator in half, because
each normally ungrounded phase generates AC power and returns it to the
next phase in rotation
A, B, C, etc.
If you do a continuity test on the stator, you should get around 1 ohm
or less from phase to phase to phase, and infinity to to the crankcase.
If you get any reading from phase to the crankcase, you have a shorted
stator.
The rectifier part has six power diodes which can be checked with an
ohmmeter. The three AC input pins on the rectifier will conduct
positive to the power output pin, and negative to the case or the
ground lead. All three readings will be the same. If you don't get a
reading on one of the six continuity checks, the diode is blown out and
the output from the rectifier will be cut in half.
The charging test has to be done with a fully charged battery, in good
condition.
The headlight must be on, too. As you rev the engine up, voltage should
rise from 12.0 volts to 14.5 or 15 volts and then drop back sharply to
12 or 12.5 volts. That tells you that the zener diode and the SCR are
working.
Then, roll off the throttle and let the engine idle and rev the engine
up again. You should see the same rise from 12 volts to 14.5 or 15
volts, followed by the same sharp drop in voltage every time you rev
the engine up and let it idle down.
If the regulator doesn't cycle as described, the zener or the SCR is
toast.
Electrosport USA makes better quality aftermarket rectifier regulators
to replace the outrageously expen$ive original equipment part.
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