alternator output

[atrovariousg]

I have an alternator that is putting out 14.4 volts when not hooked up to the hot wire.
Yet when hooked up the voltage drops to near 12 even after hours of idling.
Assuming that the batteries are drawn down a bit, is it possible that the above scenario is not a symptom of a problem but is normal?

[curtis73]

Its possible that your battery is in its twilight months. Test the battery when the car is off. If it gives 12v or less its probably toast.

Sometimes a battery shorts and some of the plates join their voltage. If so it would provide less voltage to the system. The only solution is a new battery.

Most major chain parts stores have little testers and they can test the battery, alternator, and other components in about 4 minutes. Its free

[tom3]

If you've run the engine with the battery unhooked I'd guess you fried some of the diodes and the output sure would suffer. Autozone and others can bench test the alternator for full output, free, but you need to take it off.

[DRW1000]

I would measure the battery at no-load, engine off. I tend to think Curtis is right and that two adjacent plates have fused and thus the battery output effectively contains 5 cells instead of 6.