Ambibox ambiCHARGE Home :: Open Energy Management System

Overview

This bundle implements the Ambibox ambiCHARGE Home charger as an OpenEMS EVSE Charge-Point for charge management. Bidirectional discharge (Vehicle-to-Home) management is not standardized in OpenEMS yet and is out of scope of this bundle.

The implementation is based on the protocol description "User Interface (Modbus TCP) - v1" and the EVCC Ambibox charger implementation (evcc ambibox.go).

Modbus/TCP protocol

All values are 32 bit (2 Modbus registers, big endian, most significant word first). Each physical connector occupies its own register block; one OpenEMS component is configured per connector.

Table 1. Input Registers (FC4)
Offset	Parameter	Datatype	Unit
0	Sleep	int32	0: awake; 1: asleep
2	Current AC	float32	A
4/6/8	Current AC Phase 1..3	float32	A
10	Voltage AC	float32	V
12/14/16	Voltage AC Phase 1..3	float32	V
18	Power AC	int32	W
20	Power Factor	float32	-
22	Grid Frequency	float32	Hz
26	Energy AC import	float32	Wh
28	Energy AC export	float32	Wh
30	Voltage DC	float32	V
32	Current DC	float32	A
34	Power DC	int32	W
36	Number Phases	uint32	-
38	Minimum PowerAC	int32	W
40	Maximum PowerAC	int32	W
42	Inverter State	enum(uint32)	-
44	Inverter Error	enum(uint32)	flag set
46	Inverter Temperature	float32	°C
48	Capacity (EV battery)	float32	Wh
50/52	Min/Max State of Charge	float32	%
54	State of Charge	float32	%
56	State of Health	float32	%
58	Time to full SoC	uint32	s
60	Number Cycles	uint32	-
62/64	Min/Max Charge Power (EV)	uint32	W
66/68	Min/Max Discharge Power (EV)	uint32	W
70	Battery State	enum(uint32)	-
72	Battery Temperature	float32	°C
74	Battery Error	enum(uint32)	flag set
76	Control Mode	enum(uint32)	-
78	Power DC (Battery)	int32	W
80	Charge Protocol	enum(uint32)	-
82	Session State	enum(uint32)	-
84	EV connected	bool	-
86	Seconds to departure	uint32	s
88	Departure SoC	float32	%
90	Departure Energy	uint32	Wh
92/94	Min/Max Energy Request	uint32	Wh
96	EvCharger Error	enum(uint32)	flag set
98	Energy AC import session	float32	Wh
100	Energy AC export session	float32	Wh
102	Replug Required	bool	-

Table 2. Holding Registers (EV Charger)
Offset	Parameter	Datatype	Unit
0	Target Power AC	int32	W (negative value = charge, see below)
2	Wake Up	uint32	1 (only valid value)

Target Power AC sign convention

Following the EVCC implementation, a negative target power value commands the charger to charge the electric vehicle; positive values would discharge it (which is not used by this bundle). The OpenEMS channel SetTargetPower is positive for charging; the sign is inverted when writing the Modbus register.

Source Code