Readiness: OpenEVSE Level 2 EV Charging Station
Verdict: Ready with caveats · 2026-09-03 · est. parts cost $73–$85
Cybersecurity — software & network: Review before networking
This is a cold check establishing the baseline pricing, availability, and lifecycle metrics for the OpenEVSE Level 2 EV Charging Station controller. All 57 BOM line items are physically procurable today without requiring PCB layout modifications. However, caveats exist requiring instructor intervention: several manufacturer part numbers are unlisted or obsolete (requiring active drop-in equivalents), an under-voltage capacitor spec must be corrected to maintain DC bias margin on the +12 V rail, and the snapshot's sample relay MPN must be corrected to the official 40 A/50 A mains contactor.
Action required
| Part |
Problem |
Recommended action |
| HCPL-2731S (IC8) |
Original onsemi MPN HCPL2731SD is Obsolete (0 stock across distributors). |
Order active direct replacement HCPL2731SDM ($2.72, DigiKey) or HCPL-2731-300E ($4.49, DigiKey). |
| AZ23C5V6-7-F (D1) |
Diodes Inc. MPN has zero distributor stock at DigiKey and only 30 units at Arrow. |
Order active drop-in replacement AZ23C5V6-TP ($0.24, DigiKey). |
| High-Voltage Resistors, 180 kΩ 1210 (R32–R39) |
Sample MPN CRHV1210AF180KFKE5 is unlisted across distributors. |
Order active drop-in thick film 1210 resistor RC1210FR-07180KL ($0.16, DigiKey). |
| Ceramic Capacitors, 10 µF 0805 (C5, C6, C13, C28) |
Planned MPN CL21A106KOQNNNE is out of stock and rated only 16 V, failing the lab's ≥ 25 V constraint. |
Order 35 V rated 0805 ceramic capacitor C2012X5R1V106K085AC ($0.48, DigiKey). |
| Tantalum Capacitor, 10 µF 0603 (C17) |
Sample MPN TLNK106M006R1500 is unlisted across distributors. |
Order drop-in 0603 ceramic capacitor CL10A106KP8NNNC ($0.21, DigiKey). |
| Power Inductor, 3.3 µH NR5040 (L2) |
Original MPN NR5040T3R3N is marked Obsolete by Taiyo Yuden. |
Order active manufacturer-recommended successor LCXND5050YAL3R3NMG ($0.40, DigiKey). |
| Crystal Resonator, 16 MHz (Q1) |
Planned MPN NX3225SA-16.000M-STD-CRS-2 is out of stock. |
Order specified alternative ABM8G-16.000MHZ-18-D2Y-T ($0.49, DigiKey). |
| AC Mains Fuse, 1.6 A (F1) |
Planned MPN 0679L1600-01 unlisted; BELFUSE1A footprint is a 5.08 mm through-hole box. |
Order active 350 VAC radial box successor 0697H1600-05 ($0.54, DigiKey) or in-stock legacy RST 1.6-BULK ($0.57, DigiKey). |
| External AC Contactor |
Snapshot sample MPN 899-1CH-F-C-12VDC is an inappropriate 10 A subminiature relay and out of stock. |
Order the official UL-listed 40 A inductive / 50 A resistive contactor with 208–240 VAC coil, Packard C240C ($24.99, OpenEVSE Store). |
Cybersecurity — software & network
Review before networking — The ESP32 WiFi gateway firmware exposes network services including an HTTP interface, WebSocket stream, and OTA update endpoint, but its version and dependencies could not be verified against vulnerability databases.
| Component |
Version |
How known |
Support status |
| open_evse |
9.0.0 |
inferred (inferred from documentation recommendation in lab snapshot) |
— |
| openevse_esp32_firmware |
not determined |
not determined |
— |
| espressif32 |
7.1.0 |
inferred (inferred from snapshot reference to esp32_wifi_platformio.ini) |
— |
| platform-espressif32 |
55.03.311 |
inferred (inferred from snapshot reference to esp32_wifi_platformio.ini) |
— |
| esp-idf |
5.5.4 |
inferred (inferred from snapshot reference to esp32_wifi_platformio.ini) |
— |
| bblanchon/ArduinoJson |
6.20.1 |
inferred (inferred from snapshot reference to esp32_wifi_platformio.ini) |
— |
| jeremypoulter/ArduinoMongoose |
ca0a817de014cf4ab1833b32383532366fca10d7 |
inferred (inferred from snapshot reference to esp32_wifi_platformio.ini) |
— |
| jeremypoulter/Micro Debug |
0.0.5 |
inferred (inferred from snapshot reference to esp32_wifi_platformio.ini) |
— |
| jeremypoulter/ConfigJson |
0.0.6 |
inferred (inferred from snapshot reference to esp32_wifi_platformio.ini) |
— |
| OpenEVSE/OpenEVSE_Lib |
v0.0.20 |
inferred (inferred from snapshot reference to esp32_wifi_platformio.ini) |
— |
| jeremypoulter/ESPAL |
0.0.7 |
inferred (inferred from snapshot reference to esp32_wifi_platformio.ini) |
— |
| jeremypoulter/StreamSpy |
0.0.2 |
inferred (inferred from snapshot reference to esp32_wifi_platformio.ini) |
— |
| jeremypoulter/MicroTasks |
0.0.4 |
inferred (inferred from snapshot reference to esp32_wifi_platformio.ini) |
— |
| matth-x/MicroOcpp |
1.2.0 |
inferred (inferred from snapshot reference to esp32_wifi_platformio.ini) |
— |
| matth-x/MicroOcppMongoose |
1.2.0 |
inferred (inferred from snapshot reference to esp32_wifi_platformio.ini) |
— |
| adafruit/Adafruit MCP9808 Library |
2.0.2 |
inferred (inferred from snapshot reference to esp32_wifi_platformio.ini) |
— |
| adafruit/Adafruit NeoPixel |
1.15.5 |
inferred (inferred from snapshot reference to esp32_wifi_platformio.ini) |
— |
| kitesurfer1404/WS2812FX |
1.4.7 |
inferred (inferred from snapshot reference to esp32_wifi_platformio.ini) |
— |
| rar/esp_tsdb |
2.4.3 |
inferred (inferred from snapshot reference to esp32_wifi_platformio.ini) |
— |
| bodmer/TFT_eSPI |
not determined |
unpinned (snapshot indicates caret range ^2.5.43 in esp32_wifi_platformio.ini) |
— |
| bitbank2/PNGdec |
not determined |
unpinned (snapshot indicates caret range ^1.1.5 in esp32_wifi_platformio.ini) |
— |
| lvgl/lvgl |
not determined |
unpinned (snapshot indicates caret range ^8.3.9 in esp32_wifi_platformio.ini) |
— |
No security findings — every dependency checked this run came back clean.
What this means for your lab
Anyone on the same local network or Wi-Fi segment can access the charging station's web server, live WebSocket telemetry stream, and over-the-air firmware update endpoint, which could allow unauthorized users to monitor charging sessions or modify device configuration. Because the ESP32 gateway firmware version and third-party libraries could not be checked against vulnerability databases, their security posture cannot be verified. Instructors should place the charging station on an isolated lab network or dedicated VLAN rather than an open campus network, complete the initial setup wizard to configure strong administrative credentials, and consult campus IT before connecting the hardware.
Not checked
- open_evse: no advisory database for the ecosystem (vendor AVR firmware repository)
- openevse_esp32_firmware: version not determined in project documentation
- espressif32: lookup failed (product_not_found on endoflife.date)
- platform-espressif32: lookup failed (product_not_found on endoflife.date)
- esp-idf: lookup failed (product_not_found on endoflife.date)
- PlatformIO pinned libraries: no vulnerability lookup performed during session
- PlatformIO author and git-pinned libraries: no advisory database for author libraries or git commit references
- PlatformIO unpinned libraries (TFT_eSPI, PNGdec, lvgl): unpinned caret version ranges in manifest
- espressif32 7.1.0: support status: endoflife.date has no such product
- platform-espressif32 55.03.311: support status: endoflife.date has no such product
- esp-idf 5.5.4: support status: endoflife.date has no such product
Parts
Microcontroller and Logic ICs
| Part |
Spec/Package |
Status |
Stock |
Price |
Source |
| ATmega328P-AU 8-bit Microcontroller |
32 KB Flash, 16 MHz, TQFP-32 |
Readily available |
29,655 |
$2.66 |
DigiKey |
| AP63203 Synchronous Buck Converter IC |
2 A, 5.0 V out, TSOT-26 |
Readily available |
167 |
$0.95 |
DigiKey |
| TC1044S Inverting Charge Pump |
Inverting charge pump, SOIC-8 |
Readily available (via orderable MPN) |
1,242 |
$1.26 |
DigiKey |
| LMV358 Rail-to-Rail Dual Op-Amp |
Rail-to-rail output, 5 V, SOIC-8 |
Readily available |
7,044 |
$0.45 |
DigiKey |
| LM358 Dual General-Purpose Op-Amp |
±12 V supply, SOIC-8 |
Readily available |
103,684 |
$0.26 |
DigiKey |
| AQH2223 Solid-State Relay / AC Driver |
600 V, 0.9 A, non-zero cross, 8-SMD |
Readily available |
2,545 |
$1.78 |
Mouser |
| HCPL-2731S Dual Darlington Optocoupler |
CTR ≥ 400%, 5 kV isolation, 8-SMD |
Obsolete (use drop-in substitute) |
4,495 |
$2.72 |
DigiKey |
Discrete Semiconductors
| Part |
Spec/Package |
Status |
Stock |
Price |
Source |
| MMBT2222A NPN Transistor |
40 V, 600 mA, SOT-23-3 |
Readily available |
547,932 |
$0.17 |
DigiKey |
| AZ23C5V6-7-F Dual Zener Diode |
5.6 V common cathode, SOT-23-3 |
Low stock (use drop-in substitute) |
10,352 |
$0.24 |
DigiKey |
| AZ23C2V7-7-F Dual Zener Diode |
2.7 V common cathode, SOT-23-3 |
Readily available |
619 |
$0.41 |
DigiKey |
| 1N4148 Fast Switching Diode |
100 V, 150 mA, SOD-123 |
Readily available |
1,283,914 |
$0.18 |
DigiKey |
| 1N4004 Rectifier Diode |
400 V, 1 A, SMA (DO-214AC) |
Readily available |
484,759 |
$0.26 |
DigiKey |
| P6SMB16CA Bidirectional TVS Diode |
600 W, 13.6 V standoff, SMB |
Readily available |
1,657 |
$0.61 |
DigiKey |
| MOV Surge Suppressor |
275–300 VAC, 430 V typ, 10 mm radial |
Readily available |
51,379 |
$0.24 |
DigiKey |
Passives: Resistors
| Part |
Spec/Package |
Status |
Stock |
Price |
Source |
| Current Sense Resistor, 2.0 Ω |
2.0 Ω, 1%, 0.125 W, 0805 |
Readily available |
13,114 |
$0.12 |
DigiKey |
| Resistor, 22 Ω |
22 Ω, 5%, 0.25 W, 1206 |
Readily available |
26,651 |
$0.10 |
DigiKey |
| Resistor, 100 Ω |
100 Ω, 1%, 0.125 W, 0805 |
Readily available |
111,241 |
$0.10 |
DigiKey |
| Resistor, 330 Ω |
330 Ω, 5%, 0.125 W, 0805 |
Readily available |
16,291 |
$0.10 |
DigiKey |
| Precision Pilot Resistor, 422 Ω |
422 Ω, 1%, 0.125 W, 0805 |
Readily available |
36,528 |
$0.10 |
DigiKey |
| Resistor, 820 Ω |
820 Ω, 5%, 0.125 W, 0805 |
Readily available |
13,385 |
$0.10 |
DigiKey |
| Resistor, 1 kΩ |
1 kΩ, 1%, 0.125 W, 0805 |
Readily available |
1,006,526 |
$0.10 |
DigiKey |
| Resistor, 10 kΩ |
10 kΩ, 1%, 0.125 W, 0805 |
Readily available |
1,168,650 |
$0.10 |
DigiKey |
| Resistor, 20 kΩ |
20 kΩ, 1%, 0.125 W, 0805 |
Readily available |
313,926 |
$0.10 |
DigiKey |
| Resistor, 56 kΩ |
56 kΩ, 1%, 0.125 W, 0805 |
Readily available |
44,846 |
$0.10 |
DigiKey |
| Resistor, 100 kΩ |
100 kΩ, 1%, 0.125 W, 0805 |
Readily available |
578,290 |
$0.10 |
DigiKey |
| High-Voltage Sense Resistor, 180 kΩ |
180 kΩ, 1%, 0.5 W, 200 V, 1210 |
Unlisted (use drop-in substitute) |
4,921 |
$0.16 |
DigiKey |
| Resistor, 200 kΩ |
200 kΩ, 1%, 0.125 W, 0805 |
Readily available |
60,123 |
$0.10 |
DigiKey |
Passives: Capacitors
| Part |
Spec/Package |
Status |
Stock |
Price |
Source |
| Ceramic Capacitor, 22 pF |
22 pF, 50 V, C0G, 0805 |
Readily available |
31,058 |
$0.10 |
DigiKey |
| Ceramic Bypass Capacitor, 0.1 µF |
0.1 µF, 50 V, X7R, 0805 |
Readily available |
5,566,409 |
$0.16 |
DigiKey |
| Ceramic Capacitor, 1 µF |
1 µF, 25 V, X7R, 0805 |
Readily available |
465,414 |
$0.16 |
DigiKey |
| Ceramic Capacitor, 10 µF |
10 µF, ≥ 25 V (35 V), X5R, 0805 |
Spec mismatch (use upgrade substitute) |
428,331 |
$0.48 |
DigiKey |
| Polarized Capacitor, 10 µF |
10 µF, 16 V, EIA 3216-18 (Case A) |
Readily available |
190,789 |
$0.58 |
DigiKey |
| Tantalum Capacitor, 10 µF |
10 µF, ≥ 6.3 V, 0603 |
Unlisted (use drop-in substitute) |
685 |
$0.21 |
DigiKey |
Inductors, Resonator, and Protection
| Part |
Spec/Package |
Status |
Stock |
Price |
Source |
| Power Inductor, 3.3 µH |
3.3 µH, ISAT ≥ 2.5 A, 5×5 mm SMD |
Obsolete (use manufacturer successor) |
2,896 |
$0.40 |
DigiKey |
| Ferrite Bead, 330 Ω @ 100 MHz |
330 Ω, 1.5 A, 0805 |
Readily available |
322,558 |
$0.11 |
DigiKey |
| Crystal Resonator, 16.000 MHz |
16.000 MHz, 18 pF, 3.2×2.5 mm 4-SMD |
Planned MPN OOS (use drop-in alternate) |
21,032 |
$0.49 |
DigiKey |
| AC Mains Input Fuse, 1.6 A |
1.6 A, 350 VAC, radial box 5.08 mm pitch |
Planned MPN unlisted (use active successor) |
502 |
$0.54 |
DigiKey |
| AC/DC Power Supply Module, 10 W, 12 V |
85–305 VAC in, 12 VDC 0.85 A out, 4-pin |
Readily available |
7,994 |
$7.40 |
DigiKey |
Connectors, Headers, and Test Points
| Part |
Spec/Package |
Status |
Stock |
Price |
Source |
| AC Input & Relay Terminal Header, 6-pin |
3.96 mm pitch, JST VH 6-pin through-hole |
Readily available |
11,402 |
$0.34 |
DigiKey |
| Current Measurement CT Header, 2-pin |
2.54 mm pitch, Molex KK 254 2-pin |
Readily available |
87,682 |
$0.18 |
DigiKey |
| GFCI CT Header, 4-pin |
2.54 mm pitch, Molex KK 254 4-pin |
Readily available |
55,426 |
$0.28 |
DigiKey |
| DC Relay Driver Output Header, 3-pin |
2.54 mm pitch, Molex KK 254 3-pin |
Readily available |
114,189 |
$0.23 |
DigiKey |
| Serial / FTDI Gateway Header, JST PH 6-pin |
2.00 mm pitch, JST PH 6-pin vertical |
Readily available |
29,763 |
$0.28 |
DigiKey |
| I2C Display Header, JST PH 4-pin |
2.00 mm pitch, JST PH 4-pin vertical |
Readily available |
36,565 |
$0.20 |
DigiKey |
| J1772 Control Signal Header, 6-pin |
2.54 mm pitch, Molex KK 254 6-pin |
Readily available |
12,197 |
$0.36 |
DigiKey |
| Pilot / Proximity Screw Terminal Block, 2-pos |
5.0 mm pitch, 2-position through-hole |
Readily available |
7,806 |
$0.38 |
DigiKey |
| AVR ISP Header, 2×3 (6-pin) |
2.54 mm pitch, dual-row male header |
Readily available |
29,202 |
$0.60 |
DigiKey |
| Earth Ground Test / Solder Pads |
Through-hole test point loop (or bare pad) |
Readily available |
377,642 |
$0.27 |
DigiKey |
PCB Mechanical and Trace Jumpers
| Part |
Spec/Package |
Status |
Stock |
Price |
Source |
| Solder Jumpers / Trace Bridges |
PCB copper trace feature |
Readily available |
— |
— |
Fabricated on PCB |
| Optical Fiducials |
PCB copper feature with mask opening |
Readily available |
— |
— |
Fabricated on PCB |
| Mechanical Mounting Holes |
3.2 mm non-plated/plated drill holes |
Readily available |
— |
— |
Fabricated on PCB |
External Parts Specified in Documents and Schematics
| Part |
Spec/Package |
Status |
Stock |
Price |
Source |
| Ground Fault CT Coil |
1000:1, self-test primary loop, in-line |
Readily available |
2,473 |
$14.85 |
DigiKey |
| Current Measurement CT Coil |
1000:1, 100 A rating, wire leads |
Readily available |
168 |
$15.44 |
DigiKey |
| AC Input Harness Housing |
JST VH 6-position 3.96 mm housing |
Readily available |
38,335 |
$0.17 |
DigiKey |
| AC Input Harness Crimp Contacts |
JST SVH crimp pin, 20–16 AWG |
Readily available |
1,511,736 |
$0.0552 |
DigiKey |
| JST PH 4-Pin and 6-Pin Wiring Harnesses |
2.00 mm female-female pre-crimped leads |
Readily available |
In stock |
$3.23 |
Pololu / Retail |
| External AC Contactor |
40 A inductive / 50 A resistive, 208–240 VAC coil |
Readily available |
In stock |
$24.99 |
OpenEVSE Store |
Substitutes
| For part |
Substitute |
Differences |
Verified |
Judgment |
| HCPL-2731S (HCPL2731SD) |
HCPL2731SDM |
8-SMD Gull Wing; isolation rated 5000 Vrms (exceeds original 2500 Vrms / 3750 Vrms); CTR min 500% at 1.6 mA (exceeds ≥ 400%). Direct modern tooling revision. |
package + lead spacing, CTR, isolation |
Acceptable drop-in replacement. |
| AZ23C5V6-7-F |
AZ23C5V6-TP |
Identical SOT-23-3 dual common-cathode array; nominal Vz = 5.6 V, 300 mW power dissipation. |
package, zener voltage, power rating |
Acceptable drop-in replacement. |
| High-Voltage Resistors, 180 kΩ 1210 (CRHV1210AF180KFKE5) |
RC1210FR-07180KL |
1210 thick film resistor; 180 kΩ, ±1%, 0.5 W; limiting voltage 200 V (operates in series pairs across 277 VAC mains dropping < 200 V peak per part). |
package, resistance, power rating |
Acceptable drop-in replacement. |
| Ceramic Capacitors, 10 µF 0805 (CL21A106KOQNNNE) |
C2012X5R1V106K085AC |
0805 footprint; rated 35 V (exceeds 16 V rating of planned part and satisfies ≥ 25 V lab requirement for +12 V rail DC bias). Lifecycle is Not For New Designs, but 428k+ stocked. |
package, capacitance, voltage |
Acceptable drop-in upgrade. |
| Tantalum Capacitor, 10 µF 0603 (TLNK106M006R1500) |
CL10A106KP8NNNC |
0603 footprint; multi-layer ceramic rated 10 V (exceeds 6.3 V constraint); non-polarized dielectric prevents reverse polarity installation errors. |
package, capacitance, voltage rating |
Acceptable drop-in replacement. |
| Power Inductor, 3.3 µH (NR5040T3R3N) |
LCXND5050YAL3R3NMG |
4.9 mm × 4.9 mm × 4.0 mm SMD; 3.3 µH; saturation current ISAT = 4.0 A (exceeds 2.5 A requirement); DCR = 27 mΩ (lower than original 35.1 mΩ). |
package dimensions, inductance, saturation current, DCR |
Acceptable drop-in replacement. |
| Crystal Resonator, 16 MHz (NX3225SA-16.000M-STD-CRS-2) |
ABM8G-16.000MHZ-18-D2Y-T |
Standard 3.2 mm × 2.5 mm 4-SMD package; 16.000 MHz fundamental; load capacitance 18 pF (matches C1/C2 22 pF load network). Specified directly in snapshot. |
package, frequency, load capacitance |
Acceptable drop-in replacement. |
| AC Mains Input Fuse, 1.6 A (0679L1600-01) |
0697H1600-05 |
Radial box package (8.35 mm × 4.0 mm, 5.08 mm lead pitch) matching BELFUSE1A footprint; 1.6 A time-lag; rated 350 VAC (exceeds 277 VAC mains requirement). |
package, current rating, voltage rating |
Acceptable drop-in replacement. |
| External AC Contactor (899-1CH-F-C-12VDC) |
Packard C240C |
Heavy-duty chassis mount contactor; contacts rated 40 A inductive / 50 A resistive continuous, 600 VAC; 208–240 VAC coil driven directly by onboard AQH2223 triac SSR. |
continuous current rating, contact voltage, coil voltage, OpenEVSE controller compatibility |
Acceptable primary contactor. |
Verify all substitutes against manufacturer datasheets and board mechanical dimensions before ordering.
Other dependencies
- PCB Fabrication: 2-layer FR-4 board, 91.14 mm × 51.27 mm. Requires isolation routing slot separating high-voltage AC mains from low-voltage logic (meeting UL/IEC creepage ≥ 6.4 mm and clearance ≥ 3.2 mm for 277 VAC operation). Ready for fabrication.
- Hardware Design Repository:
https://github.com/OpenEVSE/OpenEVSE_PLUS — active repository.
- Controller Firmware Repository:
https://github.com/OpenEVSE/open_evse — active repository.
- ESP32 Gateway Firmware Repository:
https://github.com/OpenEVSE/ESP32_WiFi_V4.x — active repository.
- Hardware Store / Accessories:
https://store.openevse.com — active and verified.
- HTTP API Documentation:
https://openevse.stoplight.io/docs/openevse-wifi-v4/ — active.
- Emoncms Service Integration:
https://emoncms.org — active link.
Watch list
- Taiyo Yuden NR5040T3R3N inductor: The original series is Obsolete. While distributor inventory remains, instructors should migrate documentation to the active manufacturer replacement
LCXND5050YAL3R3NMG.
- Bel Fuse subminiature fuses (RST 1.6-BULK): The legacy RST series is Obsolete despite high remaining distributor stock (>97k units). Future procurement should specify the active 350 VAC successor
0697H1600-05 or 0697H1600-01.
- TDK C2012X5R1V106K085AC capacitor: Marked Not For New Designs by TDK. Hundreds of thousands remain in distributor stock, but instructors should track active alternatives (such as Kyocera AVX
KGM21AR51E106KU).
- CR Magnetics Current Transformers (CR8450-1000): Stock at primary distributors is modest (168 units at DigiKey). Reorder lead times should be monitored for larger lab classes.