Charging Systems - Charlotte

Charging system on a Pontiac Lemans 1989

First you do a visual check, Is the belt tension okay and in good condition, no frayings, oil leak, wires in good condition and have good connection. 
Determine the condition of the battery. Is it in good condition? No corrosion, good terminal connections. What is the OCV? It needs to be more than 50% charged. 12.4v .
The OCV of the Car was 12.25v
Battery is weak, started the car , turned it off and let it sit for a while with lights on for 2 mins. Re tested and got 12.54v . Pass result.
Determning the condition of the voltage regulator. The spec is 13.5-14.5v
The engine needs to be on when testing but have no load. That means no lights, stereo. Looking for a slight voltage increase but not to high. Example, a 15v bulb with 16v flowing through, will blow because the voltage is to high.
The regulator voltage reading was 14.35. This is a pass result.
No load current, for a carburetter is 5-12amps or fuel injected it 10-18amps
The no load output spec is 10-18amps
Checked the no load current with the clamp meter around the possitive lead , expecting the amps to rise between 10-18amps. If the accessories were on, stereo , lights , heater etc the reading would be higher because there is more amperage needed to run these systems.
Charging voltage under load spec is OCV + 0.5v . The cars charging under load spec is 13.1v
With the engine turned off and all accessories on apart from stereo and wipers the recorder current drawn from the battery was 69amps.
A load test on the alternator was carried out. Connecting the voltmeter to the battery and adding load, the clamp meter was put around the alternator cable and the multi meter leads on the battery terminals with the engine running. Expecting it to be charging. low charge on a battery can result in the alternator needing to be replaced.
Measured the charging voltage under load 13.22v
output amps under load 50amps.

Voltage drop test
Positive side spec - 0.2v     negative side spec - 0.2v
P side - 0v     N side- 0v
 Positive volt drop - using a multimeter place the negative lead on the positive battery terminal and positive lead on the alternator B+
Negative volt drop - Negative lead of multimeter on the alternator body and the positive lead on the positive battery terminal .

In conclusion the OCV is low,  measured the voltage twice with two different readings. Apart from this nothing needs to be changed or replaced.