So it looks like there are some 240V capable OEM EVSE's. Unfortunately I am certain mine is not one of them. From what I've gathered from cecil-t and spirilis the differences are as follows:
OEM EVSE part #FM58-10B706-AJ
- Has thermistor in plug. Plug end cord has the following on it (3 COND 16 AWG & 2 COND 22 AWG 600V) The 22 conductors for the thermistor which is probably an added safety feature to detect if the plug overheats.
NOT 240V CAPABLE:
OEM EVSE part #FM58-10B706-AF
- Has no thermistor in the plug (3 COND 16 AWG AWG 600V) ie. no wires for a thermistor
For the curious here's supporting info on how arrived at the above. First the part number:
I believe the manufacture date (just out of frame in the picture) is in the format (year day of year). For example the manufacture date on mine is 14175. I got my FFE late in 2014 so it makes sense that my EVSE was made on the 175th day of 2014. Now for some geek porn.
The back of the circuit board:
Front of the circuit board:
In the image above, the power comes in on the left. I believe the object in the middle of the 3 blue things is the GFCI current transformer.
The blue things are varistors. One is across the line and neutral. I didn't verify but I speculate that the others go across line - ground and neutral - ground. The two blocks are the relays that connect power to car. I was surprised to see a current transformer on the line exiting the relay going to the car. Apparently there must be some logic that monitors how much current is actually being drawn while charging. The rest is mostly a mystery to me. I see a couple transformers and various other components that I assume are the power supply for the onboard logic and the current signal the EVSE sends to the car (blue wire).
Besides the fact that there are transformers and nothing resembling a switching power supply for the logic power supply, the Varistors on the input are what verified that this model is NOT capable of dual voltage. I looked up the data sheet here
for the part number S20K150. This varistor is rated for 150V. For those that don't know what a varistor is for, or how it works, they are basically cheap circuit protection. In this case, when a voltage greater than 150V is encountered, the resistance drops to practically 0. Basically it sacrifices itself in a dead short, across the power input wires, in order to save the electronics down stream from high voltage spikes. Since there is a 150V varistor across the input, it would go poof if you plugged it into 240V.
cecil-t it might be a good idea to edit your first post with the part numbers to show which EVSE can and can't use 240V so some poor schmo with the older EVSE don't kill them trying to plug them in to 240V if they don't read this far before trying it.