intermittent charge issue

[feelstranger]

Folks, I'm experiencing an intermittent charge with a newly installed Al179x alternator.  (Bosch remanufactured)
Primarily after some time on the highway - and then after "cooling off" for a while (on the side of the road, or rest area) it works for some time - though that seems to be getting more variable.
Swapping the voltage reg. had no change, and I confirmed that there was no charging  after the warning light came on.
Anyone ever have a faulty "new" alternator?
Could it be something else?   I'm relatively confident it is not an intermittent igniter circuit.
Thanks

Nat