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All of the OEM Replacement portable units and permanent home installation units appear to cost well over $1000. So I decided to look into other options such as building my own. I found the project and decided it was my best option.

At this point I have built one of three units. The page for my particular OpenEVSE build can be found at EVSE_by_4Dolio along with various other peoples builds. This is an auto-sensing Level 1 & Level 2 J1772 EVSE compliant charging solution with GFI protection. It uses Open Hardware and Software so it can be built to suit whatever ones needs are. The current limits are programmable but default to 12A at Level 1 and 16A at Level 2. My unit is built with 30A components so I will eventually increase the level 2 limit to 24A. I have yet to add true energy monitoring but intend to add that feature in the form of current measurement, reporting, and perhaps logging. Stay tuned as the project progresses...


  • When assembling the display be aware of how stand offs will attach.
  • 10AWG wire is difficult to attach to terminal blocks when the block is mounted inside the enclosure, but easy to attach while the terminal block itself is not yet mounted in the enclosure.
  • Devise a better crimp on terminal block connector than those used.
  • The L6-30 Extension cable is cut in half. The plug end used with the Open-EVSE. A 110vac plug is added to the receptical end of the L6 cable for use as an adapter cable for 110vac Level 1 use. (If desired)
  • I tinned (with solder) the ends of the wires that attach to the Open-EVSE so to keep them from fraying when attached to the screw terminals. Note that depending on the wire gauge used one may need to remove some strands to keep the tinned wire small enough to fit. None of these carry high power so small gauge wires can be used.
  • I did not solder the internal high power AC connections but rather left them as blade connections. I am not certain of these connections current carrying capacity and am open to comments and input on whether these should be changed. I chose not to solder them as I may want to modify things inside this Enclosure #1 which I am using for development purposes. The other terminal block connections are more than capable of carrying the potentially high currents.

Parts List

Key: Items with letters in the quantity field have multiple options:

  • e = Various enclosures.
  • f = Various fuse/breaker options
  • d = Only needed if adding a display
Part Source Cost Quantity Link
Open EVSE Plus Board w/ integrated power supply Open EVSE $150.00 1
J-1772 cable, 30 amps (A3435-PEV) Leviton $133.98 1 +$12.19 shipping
30A AC Plug L6-30 Stay Online $33.00 1 Good for the plug and an adapter cable
RELAY GEN PURPOSE DPST 30A 12V (PB486-ND) Digikey $13.03 1
TRANSFORMER GROUND FAULT WIRE LD (582-1018-ND) Digikey $10.65 1
BOX NEMA ECONOMY 5.9X5.9X3.54 (377-1787-ND) Digikey $20.62 1e
PANEL INTERNAL 4.9" X 4.9" (377-1939-ND) Digikey $4.80 1e
BOX ABS 7.62X4.47X2.47" TR BL (HM1056-ND) Digikey $9.35 1e Alternate Enclosure 6.0x3.3x2.0 $7.23 4.8x2.6x1.6 $5.40
2" plastic 4-40 M-F standoffs (4813K-ND) Digikey $0.63 8 7/16"
Terminal Blocks - Barrier Blocks Digikey ~$5.00 2 euro 4x 30A 10-18AWG $1.77 euro 4x 30A 10-18AWG $1.49 euro 3x 30A 10-18AWG $1.31 Barrier Block 5x 50A 6AWG $12.85
FUSEHOLDER 1/4" 30A 250V PNL MNT (283-2850-ND) Digikey $3.69 2f
FUSE BLOCK 3AG 1POS SOLDER (F1497-ND) Digikey $1.13 2f
FUSE 250V SLO-BLO 3AB 30A (F1779-ND) Digikey $1.68 2f
CIR BRKR THRM 30A PUSH-RESET (302-1268-ND) Digikey $5.37 2f Replaces Fuses
CONN TERMINAL STRIP 4CIRC 10MM (WM15910-ND) 10-18WG Digikey $1.77 2c
CONN TERMINAL STRIP 4CIRC 12MM (WM7725-ND) 8-20AWG Digikey $1.94 2c
STANDOFF M/F HEX 4-40 NYL .250"L (4800K-ND) Digikey $0.397 8(10)
STANDOFF M/F HEX 4-40 NYL .500"L (4802K-ND) Digikey $0.442 0

STANDOFF M/F HEX 4-40 NYL 1.00"L (4806-ND) Digikey $0.476 0
STANDOFF M/F HEX 4-40 NYL 2.00"L (4813K-ND) Digikey $0.528 4(10)
HEX NUT 1/4" 4-40 100/PK (H216-ND) Digikey $0.0149 100
MACHINE SCREW PAN PHILLIPS 4-40 (H542-ND) Digikey $0.0886 100
AdaFruit RGB LCD Shield kit AdaFruit $24.95 1d or
Premium Female/Female Jumper Wires - 40 x 6" AdaFruit $6.95 1d (Handy if adding a display)
Liquid Tight Strain Relief Alliedelec $3.20 2 11-21 mm or 14-25 mm or 14-25 mm black
Nut for Strain Reliev Alliedelec $0.68 2 PG-29 Nut Grey or PG-29 Nut Black
Shipping costs DigiKey, AdaFruit, StayOnline ~$25.00 1
Crimp Connectors/PCB connectors various ~$10.00 1
Hardware (nuts & bolts) various ~$5.00 1
USBtinyISP AVR Programmer Kit-USB SpokePOV Dongle AdaFruit $22.00 ? (Optional)

Parts Cost

Parts for 1 to 3+ builds

  • $150.00 - OpenEVSE 1x v4 plus
  • $293.42 - - 2x 30 Amp J1772 Connector with 25 Ft. Cord
  • $ 80.64 - - 2x L6-30 Cord 6 Feet
  • $188.00 - - Relays, Breakers, Current Sensors, Enclosures
  • $25.00 - - 1x RGB LCD Shield Kit w/ 16x2 Character Display
  • $ 36.30 - - 4x Strain Relief, 10x Nuts
  • $ 73.04 - - Stand Offs, Screws, Nuts, Terminal Blocks
  • $853.96 - Total

  • $50.00 - - 2x RGB LCD Shield Kit w/ 16x2 Character Display
  • $300.00 - OpenEVSE 2x v4 plus
  • $150.00 - - 1x 30 Amp J1772 Connector with 25 Ft. Cord
  • $ 40.00 - - 1x L6-30 Cord 6 Feet
  • $1393.96 - Total including Remaining parts for 3 units (464.65 each)

Assembly Reference

Labelled OpenEVSE Board.
(top left )(6Pins) ISP = ??Unknown?? Programming header
(top right)(4Pins) I2C = Connection for Display            

(left) AC Test 2 (Connect to AC Input, after relay) ??Confirm??
(left) AC Test 1
(left) AC Line 2 (Connect to AC Input, after fuse)
(left) AC Line 1
(right) (2Pins) FTDI ??Unknown??
(right) K1772 Pilot (???? colored wire)
(right) Ground
(right) Relay Coil 12v (To Relay, polarity does not matter)
(right) Relay Coil 12v
(right) (2Pins) CT coil ??Unknown??
(right) (2Pins) CT Self Test (future) ??Unknown??
Back side of OpenEVSE
Display Pins near buttons, (Pin3=Yellow, Pin4=Green, Pin5_to_Pin4, 6,Space,7,8,9,10, Pin11=Red, Pin12=Orange)
Display connects to 4 "IC2" pins. (Red, Orange, Yellow, Green (Corner of Board))

Build Photos of Enclosure 1

Build Photos of Enclosure 2

Build Photos of Enclosure 3

Related Photos

Photos related to the enclosures, high power garage wiring.