So with a DC-DC converter, would it just make it charge slower? And if I were to go ahead and use the solar panel and charge controller, what would be the effects?You either need:
A solar panel with at least a 15V output
or
A DC-DC converter to step up the 9V to 15V (but those have losses which will reduce the power from the panel).
A charge controller only regulates the charging current, it won't generate the higher voltage you need.
I think its more like the bunny rabbit on a treadmill with up-gearing to the road wheels.Yes, a DC to DC converter will make the charging process very slow. You have already been answered, "What will happen if I use an inadequate solar panel and a charge controller". It won't charge the battery. If you don't believe this, harness a bunny rabbit to your car and tell him to pull you to the grocery store.
Either way, you are going to be waiting a long time for all this to take place. You might as well throw a coat of paint on the wall while you are at it and watch it dry.You could charge two 6V deep cycle golf cart batteries in parallel (with a regulator) and then discharge them in series for 12V. Or you could use two solar panels in series for 18 V and use a regulator to charge 12V
Don't most people wait 130 hrs between paint coats?Either way, you are going to be waiting a long time for all this to take place. You might as well throw a coat of paint on the wall while you are at it and watch it dry.