Electrical system weird -- HELP?

[RayRandolph]

'90 Q45 57k (not an error).

The other night I drove home, headlights on, and when idling the engine kept barely stalling - rpm's down, lights dim, then a recovery (small surge). Battery was discharged when I got home.

Charging appears to be working - voltage across battery increases some when revving. No engine lights come on.

Battery took a charge overnight, seems ok.

When I rev the engine it seems normal up to about 4K rpm (and above), where all the lights start lightly pulsing (they don't go all the way dark), maybe twice/sec. Happens regardless of whether headlights, brake lights are on or off.

It is quite reproducible.

Anyone? Q45tech?

Thanks in advance --

RR

[Q45tech]

Have the alternator load tested and include the rpm where the problem occurs...................At idle the voltage across battery ~~ 13.2 minimum.

What is AC ripple from alternator?