nighthawk 550 electrical problem

Thanks Pierce. I have charged the battery overnight and will check i
this morning. From all that I ahve read so far I think it is th
Rectifier. I wish I knew how to test it

 

Maybe you're not clear on the concept of the rectifier regulator unit.

There are two parts. The rectifier and the *voltage* regulator. They
are both in the same unit.

You test the voltage regulator operation by doing the "charging voltage
test".

You test the rectifier by doing the "diode test".

Charging voltage test:
With a fully charged battery installed, start the engine. The
headlights must be on to load the alternator. Hook a voltmeter across
the battery with the voltmeter on a 15 to 20 volt DC scale. As you rev
up the engine, the
voltage should rise from 12 volts to about 15 to 16 volts. Then the
voltage should drop off sharply. Roll off the throttle and roll it back

on and the voltage should rise and sharply fall each time you do this.
The charging voltage test will prove that the voltage regulating
circuit works.

The diode test: This works best with an analog ohmmeter, as some
digital meters won't read a diode correctly. With the ohmmeter on the
R X 1 scale, check from each AC pin in the alternator input connector
on the voltage regulator to the DC positive output pin. You should be
able to tell the AC input connector from the DC output connector
because it's probably impossible to hook the AC input conector to the
DC output connector, the connectors should be "keyed" differently. To
check the first three diodes, touch the black lead's probe to the AC
input pin and the red lead to the DC output pin. If you don't get a
reading, check with the black lead from the AC input pin to the DC
output pin. You must get the SAME reading from each AC input pin to
the DC output pin. It might be around 15 ohms, but I can't say for
sure because the battery in an ohmmeter biases the diodes and causes
different readings depending on the ohmmeter. If you don't get a
reading, that probably indicates a blown out diode. Now, reverse the
leads and check the other three diodes. Whatever lead gave you
continuity from the AC input pin to the DC output pin is the wrong
lead, so reverse the leads and check from the AC input pin to the DC
negative ground pin. Again, you must get the same low reading from
each AC input pin to the DC negative output. You should NOT get a
reading in both directions, that indicates a shorted diode. You SHOULD
get the SAME reading through all six diodes, going first from the AC
input to the DC output to check the first three diodes, then reversing
the leads and checking from the AC input to the DC negative side.