OpenEVSE

Local-LAN driver for OpenEVSE Level-2 EV charging stations running the OpenEVSE WiFi v4 firmware (the ESP32-based gateway board). The driver polls /status and /config, surfaces telemetry as device attributes, and exposes control verbs (enable / disable / sleep / current-limit) via the unit's documented HTTP endpoints and the RAPI passthrough at /r?json=1&rapi=....

Prerequisites

• OpenEVSE controller hardware with the OpenEVSE WiFi v4 firmware (formerly "OpenEVSE WiFi Gateway"). The earlier v1/v2 EmonCMS-only firmware exposes a different, smaller HTTP surface and is not supported by this driver.
• The EVSE must be joined to the building LAN. The boot AP (SSID OpenEVSE_xxxx) is for commissioning only.
• A DHCP reservation on the unit's MAC. The driver talks to a fixed IP — there is no mDNS resolution path.
• If you set an HTTP password on the unit (Settings → Security on the EVSE web UI), record it for the username + password attributes here.

Setup steps

1. Reserve the OpenEVSE's IP on your DHCP server.
2. Verify the API in a browser at http://<ip>/status. You should see a JSON document with state, amp, voltage, and wh fields. If it returns a login challenge, the unit has a web password set.
3. In GEM, Admin → Devices → Add Device, pick driver openevse, set ip. If the unit has a web password, also set username (default openevse) and password.
4. Save. Telemetry attributes will populate after the first poll cycle (~10s).

Attribute reference

Required

Attribute	Type	Description
ip	string	LAN IP of the OpenEVSE WiFi v4 controller.

Optional

Attribute	Type	Default	Description
port	int	80	HTTP port.
username	string	openevse	HTTP basic-auth username. Ignored when no password is set.
password	string (secure)	—	HTTP basic-auth password set in the OpenEVSE UI. Auto-encrypted by GEM's secure-attribute hook.
status_interval	int	10000	Poll interval in ms.
request_timeout	int	10000	HTTP request timeout in ms.

Telemetry attributes (set by the driver)

Attribute	Type	Source
evse_state	string	/status.state mapped to not_connected, connected, charging, sleeping, disabled, vent_required, diode_check_failed, gfci_fault, no_ground, stuck_relay, gfci_self_test_failed, over_temperature, over_current. Unknown codes pass through as state_<n>.
evse_state_code	int	Raw /status.state numeric code.
charging_current_a	float	/status.amp (milliamps) ÷ 1000.
voltage_v	int	/status.voltage. Some units without an active CT report 0 between sessions.
charging_power_w	int	charging_current_a × voltage_v.
session_energy_wh	int	/status.wh — energy delivered in current session.
session_seconds	int	/status.elapsed.
pilot_amps	int	/status.pilot — current pilot signal duty cycle (amps).
ambient_temp_c	float	/status.temp1 ÷ 10 (skipped when the sensor returns the "no sensor" sentinel -2560).
mcp9808_temp_c	float	/status.temp2 ÷ 10.
ds3231_temp_c	float	/status.temp3 ÷ 10.
wifi_rssi	int	/status.srssi.
uptime_seconds	int	/status.up.
override_state	string	Current manual override (active, disabled, sleeping, or absent).
charge_rate	int	Current configured charge rate in amps (/status.charge_rate).
divert_active	bool	True when divert mode (solar) is currently sourcing — /status.divertmode == 2.

Commands

Command	Args	Effect
get_status	—	Returns /status JSON.
get_config	—	Returns /config JSON.
enable	—	Enable charging (RAPI $FE).
disable	—	Disable charging entirely (RAPI $FD).
sleep	—	Sleep mode — allow plug-in but no charge (RAPI $FS).
set_current_limit	amps (6–80)	Set soft current limit (RAPI $SC <amps>). Clamped to panel max by the ESP.
override	state (active/disabled/sleeping or null)	POST /override. Null clears the override. Falls back to RAPI on older firmware that lacks /override.
restart	—	POST /restart — reboots the ESP.
rapi	cmd (string starting with $)	Raw RAPI passthrough. Advanced — use sparingly.
refresh	—	Force an immediate status poll.

Zone address format

This driver does not use zones (supports_zones: false). All telemetry and control live on the device row.

Known limitations

• Current-limit clamping. set_current_limit is silently clamped to config.max_current_soft by the firmware. Requests above panel max appear to succeed but the unit holds the lower value.
• voltage may read 0. Units without an active CT report 0 voltage between sessions. Treat 0 as "no measurement" rather than a fault.
• Firmware quirk on /override. Older OpenEVSE WiFi v4 builds (pre-4.1.x) do not expose /override. The driver detects the 404 and falls back to the equivalent RAPI command. Pure v1/v2 firmware is not supported at all.
• RAPI return strings, not JSON. RAPI replies are $OK/$NK strings; the driver normalizes them to {ok:true} / {error:'rapi NK'}. The raw ret string is included for debugging.
• MQTT / Emoncms reporting paths are not used. The driver is HTTP-only. If you have an existing MQTT integration on the unit it will continue to publish in parallel.

Troubleshooting

• 401 Unauthorized on /status or /config. The unit has a web password set but no password attribute is configured in GEM. Set both username and password.
• charging_current_a flickers between 0 and a small value. Normal between sessions — the pilot duty cycle still draws a few mA on the CT. Use >= 1A thresholds for triggers.
• evse_state stuck at disabled after a restart. Send enable (RAPI $FE); some firmware persists the disabled state across reboots.
• set_current_limit appears ignored. Compare against max_current_soft in get_config — the ESP clamps silently.