Volvo: 1985 240gl, alternator, batteries

Question
alternator tests off car as ok/ has been rebuilt////not charging on car killing batteries

Answer
Don,
So you are saying the alt on the car hooked up kills the battery, well that would mean the alt is draining the battery, yet able to charge. I would say the alt was only tested for its' ability to produce a charge within a certain spec.
Or do you mean the car runs out of battery when driving, that would mean there is no power being made by the alt when running. In that case it could be the exciter wire is not powering up the alt or the alt is loosing a ground.