The other morning - cold vehicle, I started the LR3 and when the air compressor was running, I noticed that the compressor motor RPM dropped significantly when the high-idle dropped back to normal after the engine was first started.

With a proper voltage regulator and a good battery I can't think of any reason why this would happen. I do notice a "whine" when I start the vehicle after it's been sitting, rather like an alternator going under heavy load. Raising engine RPM caused the compressor RPM to increase so that was confirmed.

It's a newish interstate battery and I haven't had a single problem with it, and I know these things WILL let you know if a battery is dead. This includes a few recent single-digit temp starts.

I guess if an alternator is on the way out, the battery itself may remain fully charged, but once the car is started if the alternator isn't putting out enough current, the battery will have to pick up the load and components may be running weaker than they otherwise would.

I'll have to put a volt meter on it when it's cold and see how low the voltage drops when the high idle drops down... just wondering if anyone else has had problems. I don't recall hearing too many alternator problems on these. It's a 2006 with 92k miles on it.

 

How are you measuring the EAS Compressor's RPMs?

I had an alternator go out right around 90k miles. It whined quite loudly when it was on its way out. I thought it was a power steering belt...so that's what it sounded like, for your reference.

I'm not sure how many single-digit mornings per year you get, but FYI you can get a block heater for these things...

 

Measuring just by the noise - pretty used to it after the RRS and now this one (plus my friends various vehicles). FWIW I think I left my door open that morning I discovered it for whatever reason.

That's interesting about the mileage AND the whine when yours was on its way out. I've got a trip to Kentucky from VA (Rolex Kentucky 3 day event, title sponsor ironically is Land Rover, will be camping out at the horse park and participating in the Land Rover Tailgate event..) DEFINITELY don't want to lose an alternator on the way there.

I also have a 3 hour trip in June with a ~5500lb trailer so I'd like to get it all sorted for that trip as well.

Of course I have a weird driveline noise and the phantom starter "click" / no start issue which has since completely vanished. Kinda in triage mode for now.

I do have dealer accounts with LR and NAPA though, but yikes they still aren't cheap!

 

I've yet to find an inexpensive Land Rover part!

...except the brake switch.