2000 S70 Electrical/charging question....
 

Voltage shows 13.5 / 13.6 and didn't change much after 5 minutes of idling or so. When I loaded it down with headlights/ bright/dim, it dropped to 13.3 or so.

However when the car is driven, it just shut off on it's own on occasion for some reason while the driver is driving. It will also be dead after sitting for a while. The problem is this is intermittent.

I've read the forum and I've seen a few good solutions by you guys. However what I didnt find was what is a normal voltage for this charging system?

I think what I'm seeing is possibly a voltage regulator issue where its going bad, however This is not my car and I can't tell long-term.

Any suggestions would be great.

Battery is from 2013 and is a high quality motorcraft.

If I took the car to autozone, say, can they test the alternator if its on the car?

Yes they can test the alternator on the car while it is running.

The stalling may have nothing to do with the charging system. Have you tested the fuel pump relay?

The fuel pump relay didnt even cross my mind. This is why I cam here You guys know your stuff.

I will check it and report back.

Update: The owner said the vehicle stalls after its hot. Drive down the road, stop at a stopsign, idle goes low and BLEH it quits. Start it up again, off you go... this is common.

Auto store said the charging system is working fine.

Took the fuel pump relay off, not a slight bit of corrosion, seemed fine.

Is there some resistance it should show with a volt meter?