The system is basically designed for full output (and long life)with roughly 9 VDC supply. This is about what you have during cranking, and the ignition switch basically shorts the ballast during said cranking. When it starts, you release the key, the charging system resumes operation, battery voltage comes up to 13-14 VDC, and the ballast is again in series, limiting the current flow (and voltage at coil pos.)
