Charging issues

[JNSmith1717]

Ok so mine is different then all that I can find. When I start my car it just runs off of the battery till I Rev it to about 20 rims then it will start to charge. I do know my alternator bushings are shot and my belt isn't fully tight like it should but the belts don't squelch on startup but could still be slipping. What do you all think about this? It's a 91 318i sedan

[varg]

If by "Rev it to about 20 rims" you mean "rev it to about 2,000rpm" you probably need a new voltage regulator. The brushes or regulator itself are the likely problem.

[mjimport]

Without knowing the maintenance history of the car, I would check all the grounds first.
This can cause similar charging issues. I needed new grounds and helped tremendously with my charging issues.
Always start with the cheapest/easiest variables to fix.