Advice please...Alternator wiring problem, not charging

Hi, I've got a 200tdi defender that's stopped charging.

The alternator battery volts don't increase on idle at all, revved right up I can almost get the battery upto 13v but hardly get any increase.

I have tried 2 new alternators now so it's definitely a wiring issue somewhere?

The charge light is on with ignition and goes off as normal when the engine is started.
However without the alternator even fitted the charge light does the exact same thing, I would expect it to stay on when the engine is started when it hasn't got any alternator connected?

With the alternator in place and the ignition on but with engine off the small brown/yellow wire gives 1.6v

With the alternator unplugged I get a reading of 10.6v

With the alternator plugged in and engine started it gives 13.4v

Engine and wiring is totally started btw.

Has anyone had this issue and know what the problems might be?

Cheers

Not sure what your problem is but here are some details about alternators in general. Land Rovers tend to have a low tic over speed and it often needs a bit of a rev up to get them to start.
10.6v is low for a battery, is this at the batt terminals? Are your lights the normal level of brightness? Do they dim a lot with engine off?

13.4 sounds about right from the alternator, but 10.6 is too low for the battery, alternator might be functioning correctly and it is the battery that is given up, especially if you have the saem result with multiple alternators.

10.6 is very low, is that at idle? What voltage do you get with the ignition off and have you fully charged the battery?
13.4 doesn't sound right to me, older alternators push out 13.8, but you need 14.7 to properly charge a modern battery.
Your first check it to test the voltage between the positive post on the alternator and the casing

Most A127Alts will be high 13v when running, you can fit a tractor battery sensed brush box that has an extra wire that goes to the battery itself, then you will get low 14volts.
If the alt light is going out then I reckon you can ignore the alt as the issue.
Have you checked the wires, the fat one only goes around the engine to the starter.
Are all you earths good? Not look good but actually work good.

Forgot to say have you the correct bulb in the charge lamp?