EV Beetle Conversion Project

 The Type 1 AC inlet from a Nissan Leaf, fitted into the location where the fuel filler used to be. I cut off the top of the fuel inlet, preserving the mounting holes and created a 3D printed part to epoxy on to it so that the inlet could be screwed in to place.  Quite pleased with this, although it still need to actually finish wiring to the front of the car where the charger will live.

 The wall boxes for charging EV's aren't actually chargers, they are just a fancy 240v (some can also be 3 phase) outlets.  The protocol is pretty simple, and can be found on Wikipedia. https://en.wikipedia.org/wiki/SAE_J1772 There's basically 2 signal lines, Pilot Proximity and Control Pilot, the control pilot is a 1 khz PWM signal, where the duty cycle represents the maximum current the car is allowed to draw. The proximity pilot is a fix resistance, one of 2 values. On denotes the plug is connected, another that the release button is pressed so the charger can immediately stop drawing current and so stops arcing. Inside the wall boxes are simply a EVSE protocol controller, an RCD, possibly a GFI and a relay/contactor. They are insanely expensive for what they are, so I've designed a simple circuit board that makes use of an Arduino Pro Nano, a cheap and widely available micro controller and a simple program that implements the bare minimum of the protocol.  The code

 I picked up a 3.3kw charger from a Mitsubishi Outlander from Ebay for just over £150 delivered. This little unit is a CAN Bus controlled charger that's pretty flexible, it also has a pretty powerful DCDC converter built in to keep the 12v battery charged from the main pack, it requires liquid cooling. You only need 2 messages to control the charger, ID:  0x285 with byte 2 set to  0xb6 will load the control pilot to signal to the EVSE that a charge is requested. ID 0x286, the second byte sets the charge current desired (current * 10, so 30 for 3 amps), what ever is used to send these signals will need to watch the voltage to ensure it doesn't go over your desired battery voltage, it'll increase the voltage up to 420V I'll be using either a Teensy or Arduino to control it in the car, but here I've just got SavvyCan spitting out the messages and we're charing at 3 amps. :D  https://github.com/jamiejones85/DBC-files contains the DBC files to interpretate the CAN me

Having deliberated over battery pack options, I was convinced I would go for a pack from a BMW plug in hybrid or the Outlander PHEV, but a pack from a Golf GTE popped up on eBay for £500 delivered, which was too good to let pass by, at 8.8kwh it works out at £57 per kilowatt hour, a bargain. Tearing it down wasn't the easiest task, and with 350v - 400v under there, a little nerve wracking. The lid was glued down with some serious adhesive. The pack consists of 4 modules, each module is 2 strings of 12 cells, with a cooling plate between them for liquid cooling. Each of the 12 cells has a BMS slave board, which reports the voltage of cell cell to the BMS master, along with the temperature of the string. Each module can store just over 2 kwhs. The modules communicate with the master via a CAN Bus network that's internal to the battery. I've put up a GitHub repo with a DBC file for interpreting the reported frames https://github.com/jamiejones85/DBC-files if you are looking at