The tensioner definitely isn't limp. I spun the rest of the pulleys and everything seemed fine. I replaced the PAS pump about 1500 miles ago and have been a little leery about reman, but it looks fine.

I think you're right about the AC clutch bearing. The last day I drove the Rover there was a moment when my son and I smelled something strange in the cabin, I was afraid something was burning. I was able to drive him about 2 miles to school and by the time I got back the M & S lights were flashing at me (limp mode I believe?). I've left it parked since then. I've ordered the bearing parts from a parts store as well as a used alternator. I'll probably replace the belt while I'm at it to be safe.

 

Hi Robert, it sounds like either a bad connection or the alternator is going bad.
In theory once a vehicle is actually running the battery plays little or no part as the alternator takes precedence and at the same time also charges the battery.

It is possibly the brushes in the alternator or the rectifier unit/power regulator unit going defunct. If it's the alternator take the D2 to a good auto electrician to test it out, IMHO it's an alternator or a connection problem. I don't know what additional equipment has been added to your D2 but also check for a parasitic power discharge as the battery light also appears when the alternator or battery are defective.