I have a 2015 with the 8 volt batteries run in series. I’d like to put new batteries in use 12 volts 6 of them the same way.(?? will this cause any problems with codes etcetera? it shouldn’t right?
What car do you have? I’m guessing e6?
It shouldn’t cause any problems but you might need to change the charging profile to suit your new cells or risk cooking them.
Why the switch?
Realize that you will probably not have as much range with the 6)12v battery pack vs the 9)8v pack.