There's two possible reasons for the extreme charging on a normal system.
1. Battery was very low, and sucked a lot of current from the alternator after starting.
2. The voltage regulator isn't controlling the output voltage. So with increasing rpm, the voltage goes up.
> a. One cause can be the regulator seeing a lower voltage than the rest of the system is at due to poor connections.
>b. Another cause is internal or wiring failure bypassing the regulation. Del just mentioned a couple of ways outside of the regulator that this can happen.