70 up charging system upgrade question

I measured battery static direct at battery posts.
"Run" was measured at batt -ve post and the red battery connection at switch.(I weasled the lead in there). Everything hooked up.
Good idea with jumper wire.
Sorry but now with jumper in switch, what/how am I measuring at ballast?
I also have another ign switch too.
Thanks Del.
Battery static is 12.20 V.

IF "IF" you are measuring this AT the igntion switch IE the battery wire going to the switch, AND WITH the key in the "run" position, then the switch or the connector is your drop, or at least a whole big bag of it

To fully test this, round up a couple of male spade/ flag terminals and make a short jumper wire with no14 or so. Disconnect the switch, and jumper the switch connector from the red batt to the blue. Go out to the ballast and see if things improve