106 battery light driving me mad, please help!!!

Hi

Sorry this is rather long-winded, I just want to explain it fully and
see if anyone has any suggestions as this problem has stumped two
local, highly recommended garages!

I have had four replacement alternators in the past eight months, from
two different garages. The first was fitted by a garage in a
different part of the country, and was found several months afterwards
by my local place to be faulty; the light wasn’t coming on as it had
done before the replacement, but there was a nasty noise coming from
it (sorry, not technically minded!!). Since that first replacement,
each subsequent one has followed the same pattern. There is no
problem for about 600-700 miles, then the battery light starts to
appear briefly while the revs are high. This gradually gets worse
until the light is on nearly all the time, at which point I’ve had the
alternator changed under warranty. The garage have checked the car
thoroughly and been unable to find anything wrong.

The car has also been to the local Peugot dealer, in my frustration.
The first time, when the car was connected to their computer, nothing
was found as the light wasn’t on. The second time, they told me that
the fault definitely lay with the alternator, so I had it changed for
the fourth time. I do not believe anybody, even me, could be unlucky
enough to have four faulty parts in a row, so does somebody please
have any suggestions (apart from selling the car, which although
tempting at times is not financially feasible for me at the moment!)?

Any ideas would be greatly appreciated, as I can then ask the garage
if they have checked out specific possibilities. I know nothing about
cars, but thinking logically, if it was dodgy wiring surely it would
be more random and I wouldn’t have the gaps after repair with no
problems? I’ve also asked if anything could be causing the
alternators to go wrong but no solution has presented itself.

Thanks for taking the time to read this lengthy explanation!