[stevesnj]

Originally Posted by ls1ac

The new systems are smart.
The old voltage regulators were slow to react and were not very accurate.
After starting you should get 14.2 or 14.4 depending on where you measure. that is full charge voltage the amps depend on the state of the battery. After the battery approaches full charge the voltage will drop to about 13.6, this is a maintain voltage for the battery. If it stayed at 14.4 it would over charge and convert the water in electrolyte to gas. A comin problem with old cars. The new cars often have a voltage and charge sensor connected to the battery terminal.
I might suggest that you check the battery terminals to make sure there is a good connection, then do a load test on the battery. A lead acid battery that has been fully discharged will have a loss of load capacity each time it is fully discharged. (The exception are deep cycle type.)
It is possible you have a bad regulator. Excluding the sensor type most are "one wire" type and are built into the alternator.
Even if you put a battery on a new smart charger, out of the car, you will see the same kind of a voltage drop.

I would think the ECU would put up a CEL if the voltage isn't within spec?