Your alternator's regulator would still regulate the charge to the battery to keep it at original levels. However, if that were changed you basically would be putting more amperage through everything. Great for most things like lights
I doubt unless a more modern design alternator that you'd "top" it off. Similar problems to many 12v trickle chargers that never bump up. It requires your alternator to push it to full.
Gauges and smaller light bulbs may not like the extra voltage. I think a better choice would be a dual post battery with 16v to starter and ignition (if aftermarket type) and 12v to accessories. Headlights should work well on 12v if properly relayed to battery with adequate gauge wire. Don't many suggest that the AMP gauge is one of the culprits in our Mustangs?
69 351 TKO Sport Roof, Ride Tech coilover
70 557 PG Mach I tube chassis 2650lb
70 427 TKO Sport Roof, SoT full chassis to be
70 351 FMX Mach I
67 347 TKO Coupe SoT/CAT5
67 289 C4 Coupe stockish cruiser
69 460 TKO Vert, Mustang Plus Grab a Track
94 351 TKO AIX, Maximum Motorsports
01 5.4 4L80E Twins and CrMo caged
I just sold a alternator to roush for their race car that we had to put a adjustable regulator on ,alternator now charges at 15,7 volts to keep up the 14 volt battery.just thought this might help all the low voltage problems we have with our classics,
Admittedly the electrical systems on vintage cars aren't that great but I'm not sure upping the battery voltage would help signifigantly. IMHO most of our Mustang problems can be rectified simply by replacing parts/wiring and doing minor upgrades. Such as headlight relays and updated alternators. It's well known that there are quite a few benefits from upgrading from 6 to 12 volts so there might be something there. At one time there were serious proposals to ramp up the electrical systems on all new production cars to 42 volts. I'd like to see more input on this 14 volt business.