you gotta remember that 3-6 volts batteries in series won't give you 18 volts.It will give you way over 18volts(2.11 volts per cell X 9), and unless you drain the batteries first ( bad idea) you will always be over 18 volts and disqualify yourself at any show that they measure your volts. plan carefully before your proceed and make sure it's the right path for you. research is the best thing you can do before spending all your money.