when we were looking at a electric hybrid, virtually all of them could be charged from a 120V/20A outlet, charging time was on the order of 12-15 hours on a 120/20A. The other option was 240V some 30A, some 40A. Then charging time is down in the few hours.
Now with that said, if you want to convert your 120V/30A to 240V ONLY for charging just a quick change to a double pole breaker in the box, replace the 30A RV with the correct 240V outlet. The vehicles we looked at when charged on 240V did not need a 120V leg. If that is the case it's an easy conversion, two hot legs and a ground, black tape on the white hot wire. If the 240V charging needs a 120V leg, then you need a new run you'll need two hot legs a neutral and a ground, 3 wires instead of the 120V/30A with a hot, neutral, and ground.
Now, if the 240V needs to be over 30A, unless you oversized the wire to start with, you'd need new wire and new run as well.
So......... Look carefully at what the 240V requirements are. You may be lucky, may need new runs.
And if you convert the existing to 240V with no 120V leg then you won't have a 30A for the trailer either.
If you do convert to 240V, ABSOLUTELY POSITIVELY INSTALL THE CORRECT 240V OUTLET FOR THE AMPERAGE THE CIRCUIT IS RATED FOR AND THEY TYPE OF CIRCUIT (3 OR 4 WIRE PLUS GROUND). DO NOT UNDER ANY CIRCUMSTANCES JUST WIRE A RV 30A FOR 240V!!!!!
2011 Keystone Outback 295RE
2004 14' bikehauler with full living quarters
2015.5 Denali 4x4 CC/SB Duramax/Allison
2004.5 Silverado 4x4 CC/SB Duramax/Allison passed on to our Son!