1993 Lexus Es Hi M Argentina Much Spare Parts Repair Alternator Internal

hi, i´m from argentina, no much spare parts here. I repair my alternator, the internal part with copper wire redone, and the rest too. when the mechanics try it in the trial bench(outside the car) the results came ok ( 65amp charge).... when it place it in the car, and start the a/c, lights and other stuff, the charge from the alternator drops to 30 amp, so the battery is gonna die if i run the car like this. what can I try? I went three diffrent mechanics. the check engine lights still on every time i turn the car, but oil, water temperature, and transmission works ok. Whats the alternator charge from factory?is 65 amps or is it more? thanks!!!