Now then..out and about the other day and the Alternator light illuminated, so only 3 miles from home so returned with the battery very low, there was no charge getting into the Battery. I checked the alternator(Alton single phase) and its fine but nothing coming out of the original Lucas Rectifier, I bought a Podtronics 200 single phase, fitted this and after some fettling all seems well charge going into the battery...but...the alternator warning light is permanently on, I have checked the Voltage into the light (Old School bulb) and its 12.2 bike not running then increases accordingly with the motor running...but it remains resolutely ON, I changed the Light bult do-hickey control unit but no its is ON, any ideas?
The Warning Light Assimilator is really only an alternator monitor. It tells you nothing about battery charging, only that AC current is being made by the stator. It has three wires Ground (Red), Stator (Green/Yellow), Warning Light (White/Brown). When the stator is producing enough AC voltage, the device opens the internal connection between ground and the white/brown and the light turns off. So, when it came on, your stator was not making enough AC current. Since the battery was also low you had multiple problems.
Assuming your battery is fully charged: If your battery voltage is really 12.2 with the fuse removed, then you need a battery. If it is 12.2 with the fuse installed, then you have something drawing power. The PODtronics does draw power but not enough to drag the battery down that much.
Testing: Remove the assimilator - it is not needed in any way for normal operation - do not reinstall it while testing.
Quick: Check and record the voltage across the battery with the bike turned on to the ignition position but not running. Start the bike. Rev to 3000 RPM. The voltage must be at least a little higher than the voltage you recorded - if it is, you are charging.
Detailed: With your meter on AC voltage and the stator disconnected from the PODtronics, start the bike and check the voltage across the two stator wires. You must have more than 16 volts AC for the PODtronics to be able to make the proper DC voltage. At around 3000 RPM, I'm guessing you should see around 30 volts, but I am not familiar with Alton. If the AC voltage is good:
a. Reconnect the stator wires, remove the fuse and check the DC voltage.
b. Put the fuse in and check the DC voltage and compare to the voltage with the fuse out. If they are more than slightly different, you have something drawing power that should not be.
c. Turn the key on to ignition (no lights) and check the DC voltage. If the voltage drops much, you need a battery or your master switch is making a poor connection, the fuse holder is making a bad connection to the fuse, or the coils or associated wiring have a bad connection.
Once you're sure everything is OK, you should get an actual charge monitor as other have said. They check the charge voltage getting to the battery, not just that stator is producing AC voltage.
