Alternator voltage output

[DAndy ART]

The alternator is putting out 14.8 - 15V across the battery.

1967 Dart with later model 318ci.

New optima battery.
New block-chassis strap.
Cleaned battery-block ground connection.
+ve wire from alternator not hot.
No -ve voltage drop battery -ve to alt case, bolt or mount.
No +ve voltage drop battery +ve to alt post, wire or nut.

What is next?
Is volt reg on the blink?
Is 14.8 -15V normal for this era of alt?

Can I drive it for a half an hour without killing something?

 

[Michael Brisebois]

I would expect to see 14.5, yours is a little strong. I don't think you have anything to worry about.

 

[Murray]

Top voltage should be 14.4v. If it was 14.5v I wouldn't worry, but higher voltages will boil the water out of the battery. Replace the regulator.

 

[tonysrt]

The other thing to take into account is accuracy of the voltmeter. In cold weather output would be higher and after a start volts would be high to recharge battery. When it's winter voltmeter reads high, on my 05 Ram, there is no volts on meter, but since battery is 13 years old it's safe to safe everything is working fine.

 

[Mattax]

Pretty much in line with the FSM, depending on temperature. That's a different regulator than factory (US), but don't think that matters for your question.
Most items will actually run a little better at higher voltage. Running at battery voltage (12.5 -12.8) draws more current to get the same power. That's when things run hot.

If you want, check for voltage drops. Those will cause the regulator call for a higher voltage. I see you checked for some. Check at both sides of the regulator as well.
edit:see below.

 

[kursplat]

if your worried about driving it for 30min, add some load(headlights) and see what it comes down to

 

[Mattax]

This isn't quite the same as the '67 shop manual but similar.
1963 MTSC regulator test 2
Under test 1, colder temps => higher voltage.
Under test two, at higher rpm, low electric load may result in an increase up to 0.7 Volts more than in test 1.
(These are for the electro-mechanical regulators)

Here's how to do the resistance tests.
1969 Chrysler Imperial Charging System Diagnosis Service Guide from the Master Technicians Service Conference Session 256
Or, start by checking each connection from battery neg and positive, and alternator output to the regulator and then to the field terminal. Bright and clean contacts, no loose or broken wire strands at the terminals.
edit:
From '67 FSM
The voltage drop test from Battery Positive to Field side of regulator with ignition ON, engine off, should not eexceed .55 Volts. (disconnect leads at ballast for this test). I don't know if that will work with the electronic regulator. I tried it but don't recall right now.
For the the tests from Battery to alternator, they are looking for less than .3 Volts when a 10 Amp load is applied.

Finally at 47* F; min. setting 13.6 V, max. setting 14.6 V.
Adjust voltage setting within this range to match driving habits. if battery is in low state of charge, increase toward upper, and if it is shpowing evidence of over charging, adjust lower.

If the regulator you are using is transistor type, then obviously no adjustment is possible. You can try a Standard (SMP) VR128 - looks similar to the one in your photo.

What has the ammeter been showing? If the voltage is actually running high, the ammeter will show the battery charging when its already charged to max. After starting, the meter should show charging around 5-10 amps and drop off to zero within a few minutes. If it fluctuates while driving, like after coming to a stop, then its possible the alternator has a bad diode and is putting out 2/3 of what it should.

 

[KitCarlson]

The easiest way to check the regulator, is to measure the voltage on the blue wire of the regulator to ground. It should be about 13.8V, but varies a few tenths with temperature. The voltage increase at the battery is what it takes, due to the voltage drop between the blue wire and battery. The voltage drops are at bulkhead connections, ignition switch and associated wiring. Fixing drops, decreases battery over voltage.