Alternator Problem?

[Moneypit]

Hi All.
Last couple of days my midas has been playing up.
It's got the A+ 1275 metro engine with electronic/pointless ignition.
I've been using it since October, 5 days a week, going to work with no problems.
2 days ago, before the engine was really warm, it kept cutting out (mainly at junctions etc) but would start again no probs.
Came home checked a few things over, connections ,dashpot etc. Set off again and got to work without a hitch (9 miles). No problems on the way home.
Next day, same thing but went straight to work.That night though ,on the way home (2 miles from home) packed up completely at 40 mph.The battery was flat and no chance of starting.An hour later, jump started it and got home where it died again.
What I had noticed was that before the problem the revs would lessen the more load you put on the alternator(as I would expect).With the problem, revs didn't alter.I presumed alternator trouble, but at no time has the charge light come on (am I wrong in expecting this?)
Checked the battery voltage today with the car running and it was about 13.5 volts with and without any load.As the car got to running temp though the volts dropped to 11.25.
Quite happy to get an alternator, just wondering if you guys any ideas if it may be anything else?
Many thanks
Sorry for long post.

[Hans Efde]

If you have the standard Lucas ignition, the black electronic module at the side of the distributor could be faulty. It may run fine at idle, but under load it may cut out. I had it on my first Midas, it made me mad, because you can't troubleshoot it. If you have a spare module or a spare distributor or module you could give it a try. Although it didn't cause a flat battery on my car, just spurious cutting out of the engine.

[Moneypit]

Thanks Hans.Something else to look at!
I wonder if the low voltage could cause problems there even if its not a faulty module.A bit out of my depth so just guessing really.
I must admit I would have thought the charge light should come on though if the alternator was faulty?
No spare dizzy I'm afraid, only off a 1 litre engine somewhere and I'm sure that's different.
Thanks again.