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I think that in my spare time I will try to make one. An instructable will be made for anyone else who wants to attempt to make one.
I am (slowly) working on my own charger, mainly as a way to learn about it.
My goal is a portable charger that can be used when going to a friend's house either for a few hours (i.e. to share a meal) or overnight. To keep light and compact, I decided to design it for a 30Amp circuit (24A continuous). In a typical house, the laundry area is near or in the garage, so I picked a cloth dryer as my plug of choice.
This is a very basic but safe unit: it has a GFCI, and it implements the full diode check protocol.
Parts wise, I ordered a 30A cable from a supplier in Arizona which name's escape me at the moment. I was about $300~$400. I'm using a 30A contactor, from Digikey. The GFCI is a "donut" model meant for a hot-tub (available from any hot-tub and spa supplier). I have a tiny power module that takes anything from 90VAC to 240VAC and outputs 24V. From there I create +/-12VDC and +5VDC to power my processor. The "brain" is an Arduino Mini-pro. I have most of the code written which takes only a few KBytes. There is a relay under control of the Arduino that can control the main contactor, in series with the GFCI: as a result, for power to be present, both the GFCI and the J1772 protocol must be happy.
The whole thing fits in a outdoor grade box (meant to be used for industrial control boxes), sourced from McMaster-Carr. I think it is 7" x7" x5". There is no user interface other than the GFCI reset and test buttons. I figure most cars have plenty of indicators built-in to let the user know what is happening. A possible extension would be a Bluetooth serial port module that would allow me to use my mobile phone as an interface... I figure I'd get the basics right first and the bells and whistles later!
I will post some updates and pictures here soon.
 
I am (slowly) working on my own charger, mainly as a way to learn about it...

Cool! I know you are definitely a 'maker' of all sorts of things.
Sorry to correct you, but as you probably know, the "charger" is in the car. So people tend to refer to these things as the EVSE or charging equipment.

...Parts wise, I ordered a 30A cable from a supplier in Arizona which name's escape me at the moment...
Probably these guys:
J1772 Adapter
 
Cool! I know you are definitely a 'maker' of all sorts of things.
Sorry to correct you, but as you probably know, the "charger" is in the car. So people tend to refer to these things as the EVSE or charging equipment.


Probably these guys:
J1772 Adapter

Yes, I got the cable from Tucson EV. I just noticed a significant drop in prices: the 70A model (plug + cable) is now down to $250. This is a lot less than I paid for my 30A cable a few months back! I hope this will lead to more DIY projects.
 
A Leaf friend bought his EVSE at Lowes.

My Nissan Leaf Forum View topic - GE Announces WattStation Electric Car Charger
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