The point is: all things being equal; 12 volt devices typically require half the current of a 6 volt devices to operate. If a 12 volt device and a six volt device both need to a certain wattage to work, the 12 volt device would require half the current to make the same power (P=IxE). All ammeters already have shunts (to protect the galvanometer itself). Hence, six volt wired systems typically have heavier gauge wire than 12. My truck has all the normal accessories including fog lights, radio, CB, etc., no problems and the ammeter works as it always has.
don
