Hi Guys,

So I just need my mind putting to rest based on some reading off the forum around the alternator.

my 2010 5.0SC starts fine and no errors on the dash etc (which ) is a good thing. Having had a P38a before, I bought a cig lighter volt meter to keep plugged in so I can keep an eye on the voltages. My last Rangie cut out in the middle of a junction before so wanted to be at least aware fo a problem before i get to that point..

When I start the engine, volts go up to 14.4/5 and if driving local tend to stick around that but as I drive it for a bit longer, like yesterday, and taking into London the volts steadily drop and sit around 12.7 - 13.1.

Now, my questions is, is this due to the intelligence of the alternator knowing there is sufficient charge in the battery and it doesn't need the charging voltage of above 14v or if not, is this a symptom of something that needs replacing.

Just wanted someone with a little more knowledge on this than I to confirm if this is working as expected

Many thanks (as always)

Tim

From the manual :-

Regulator
The regulator provides a controllable variable voltage output from the generator. A threaded copper post connection on the
generator outer casing supplies the rectified and regulated DC current from the generator, via a large diameter cable to the
battery positive terminal. A 3-pin electrical connector located on the rear outer casing provides 2 terminals for the
hardwired generator monitoring and control connections to the Engine Control Module (ECM), and a single battery sensing
connection between the regulator and vehicle battery positive terminal via a 5 amp fuse located in the Central Junction
Box (CJB).
An additional diode is located within the regulator and is used to control feedback through the battery voltage signal line.
The ECM contains software maps that provide a mathematical model of battery electrolyte temperature, and constantly
receives information from the regulator regarding the actual battery voltage. Based on the information received from the
regulator, the ECM communicates a predicted output voltage to the regulator that is required to effectively charge the
battery without causing overcharging. The regulator adjusts the supply voltage to the battery to meet the required output
voltage determined by the ECM. This control cycle is repeated under a closed-loop condition.
The ECM monitors the generator for mechanical failure or a fault in the connections between the generator and ECM. If a
fault is detected a Diagnostic Trouble Code (DTC) is stored in the ECM memory, and if necessary, a message is
communicated on the high speed Controller Area Network (CAN) bus to the instrument cluster to illuminate the charge
warning indicator lamp.
For additional information, refer to: Instrument Cluster (413-01, Description and Operation).
During engine starting, the charge warning indicator lamp is illuminated in the instrument cluster when the ignition is
energized, and is extinguished when the engine starts and the ECM detects a generator output voltage.
During engine idling, varying electrical loads will affect the engine idling speed. To maintain the correct engine idling
speed, the ECM constantly adjusts engine fueling in proportion to the actual battery voltage information received from the
regulator.

It is similar to what happens on my Toyota actually. After having been stranded with a dead alternator that also killed the battery, I now also have USB volt meter and see the same thing. I think you're right, this does sound like smart charging (designed to reduce fuel consumption) at work. MY 2010 5.0 SC Galway green and sand interior!!
Have the Faultmate MSV2 Extreme to be tinkering with the settings etc. !!

What you describe is quite normal. In fact IMHO looks very healthy. John
2008 Stornoway Grey 3.6 Tdv8 Vogue
2005 TD6 Java Black Vogue - Written off!!
GAP iiD BT
2003 Discovery TD5 Auto, Nanocom Evolution - gone to a new home!
MasseyFerguson 152 - No electronics!! - Sold

Thanks Guys.

Most reassuring

Tim