Go back and redo your voltage test (still with the engine on), a voltage reading of 13.0 or higher indicates your alternator is still supplying a full charge while underheavyload.
Jarama's fastest right - hand kink (more than 100 mph) is over a slight vertical top (positive vertical g - load), and is followed immediately by a quick left - hand flick underheavy braking, while then turning back to the right.