I have a 240 volt, single phase, 3 wire, 10 amp, 60 hz battery charging system for a small electric car but have no 240 volt outlet. I do however have a 120 volt outlet. How can I change the 120 volt outlet to accommodate the 240 volts? I know I will have to get a new outlet, but I am asking about the wiring! Can this be done without a step up transformer?

If there are other outlets of any kind on the circuit then no. You could run a new circuit. Keep in mind that electric vehicle charging equipment is considered a continuous load. The circuit should be sized at 125% of the maximum load.

My guess would be that since this is a consumer product it should be plug and play.. but, I suggest hiring an electrician as there is an entire article in the code book for electric vehicle charging equipment. It really isn't a do it yourself project as equipment other than the charger itself may be required depending on what the manufacturer of the charger built into the unit. Check out article 625 of the NEC for more info, there is a link to an on line copy in a sticky post at the top of this forum I believe.