New To This From The UK

[Sneakkk]

Hi All,

Glad I came across this forum there is a lot of information on here! hope don't mind me being on here from across the big pond!

I have a BMW i8 12v for my daughter running 2 x 6v batteries with standard motors I'm guessing?

I have already added pink LED strips on a rocker switch for her so she can turn them off as and when she wants (will add pictures soon)

I want to convert to 18v so what's the best way to do this? or would 24v be a better option?

Any recommendations would be appreciated!

Regards
Callum