240V EV Charging for $5

 

We recently purchased a PHEV which came with a portable home charger/EVSE.  It plugs into a NEMA 5-15R outlet, and supports a maximum charging rate of 12 amps.  At 120 volts, the maximum charge rate is 1440 watts, and the charge rate reported by the vehicle is usually 1.3 kW.  The vehicle supports level 2 charging at up to 7.2 kW, but I didn't want to spend $400 to $500 for a good quality 30 amp level 2 EVSE.

The label on the portable EVSE listed an input of 12 amps and 120 volts, however I suspected 240 volts would be fine.  The EVSE just passes through the AC power, generating a PWM signal on a control wire to indicate the amount of current the vehicle's on-board charger can draw.  Of course, it's possible some home EVSEs for the North American market are built as cheaply as possible, and may not handle 240V.  I am confident our Kyungshin IC-CPD is built to accept 240V.  On the vehicle side, I checked the on-board charger label and saw that it has a wide input voltage, with a rating of 70-285Vac.  I have a 14-30R 240 volt outlet in my garage, which is the same type of outlet an electric dryer uses, giving me an available source for 240V power.

To make an adapter for the portable EVSE, I used the cord I cut off a broken dryer, and a 5-15R connector.  I used an Eaton 4887, which costs about $5 at local electrical suppliers.  The Leviton 515CV is another option.  The specs for the 4887 lists an input wire size of 12 to 18 AWG, however the 10 AWG stranded copper wires on the dryer cord were just able to fit.

With my portable EVSE adapter hack, the vehicle now charges twice as fast.  It's probably more efficient too.  The output of the on-board charger is 240-430 Vdc, and boost converter efficiency increases with a smaller difference between the input and output voltages.