Electrical troubles: battery doesnt charge

Hi All.
1972 combat battery doesnt charge.
First iI want check if the alternator works:
1. what is the good value of power out the alternator?.
Second i will check the power out fron the rectifier (with ir without the diod working)?:
2. what is the good value of power out the rectifier .
Third: what i must to do more?.
Thank you.
Piero

I would start first with ensuring all the associated wiring is in order, and that the fuse and fuse holder are in good condition. Yes, I have had an open fuse that looked fine through the glass, but was proved otherwise with a continuity check.
Next, perform the rectifier test, as all you need for that is a reliable DMM (as long as it has diode check capability).
Third, check for continuity/shorting to ground on the stator.
Finally, construct the output tester as described in the manual.

I might also mention that you should download the manual before starting any of this, and have a close look through the Electrical ("J") section. Go to http://classicbike.biz/Norton/Norton.htm
and download the manual from there.

To answer your questions in order,

pierodn said:

Hi All.
1972 combat battery doesnt charge.
First iI want check if the alternator works:
1. what is the good value of power out the alternator?

Click to expand...

First, build one of these if you haven't already:

Then, perform this check:

pierodn said:

Second i will check the power out fron the rectifier (with ir without the diod working)?:
2. what is the good value of power out the rectifier.

Click to expand...

Use this page for bench-testing the rectifier; you can use a meter in place of the battery/bulb. However, by using the bulb, you remove all doubt as to how much current the rectifier can support:



Nathan

Most electrical problems are bad grounds or bad connections. If any of the barrel connectors are old, replace them. You'll know more after you test the alternator output and the rectifier.

Hi.
Yes i understand.
But can i know a correct output value of the alternator?.
Thank you.
Piero

The lower line is the output for the RM21 which I believe your bike should have.

http://atlanticgreen.com/images/lucasrm24.jpg

pierodn said:

But can i know a correct output value of the alternator?

Click to expand...

http://www.aoservices.co.uk/info/ALTERNATOR_COLOURS.pdf

"Testing the Stator"
"The Rotor /Testing"
"Full Output test"

Click to expand...

I like that paper from AO Services, but have to wonder:
Why do we have to measure for amperage output from the alternator, when they are advertised as having a certain wattage for output.
Put another way, don't we want to know the output in watts AC? And if so, why don't we look for that?

Mr. Rick said:

I like that paper from AO Services, but have to wonder:
Why do we have to measure for amperage output from the alternator, when they are advertised as having a certain wattage for output.
Put another way, don't we want to know the output in watts AC? And if so, why don't we look for that?

Click to expand...

A simple conversion... amps X volts = watts, or: watts / volts = amps

When you say the battery won't charge, have you checked the voltage at the battery with the engine running? The charging system could be working correctly but if the battery is bad, it won't take a charge.

Mr. Rick said:

I like that paper from AO Services, but have to wonder:
Why do we have to measure for amperage output from the alternator, when they are advertised as having a certain wattage for output.
Put another way, don't we want to know the output in watts AC? And if so, why don't we look for that?

Click to expand...

Yes, knowing the wattage is good, but meters measure volts or amps, not both (watts). An output check would measure one or the other.