Voltage and current readings look ten or hundred times too large. Why?

Victron Modbus TCP registers use scale factors. Voltage values are transmitted multiplied by 100, and current values by 10. If your client does not apply these scale factors automatically, divide the raw register value accordingly. The ModbusCloud template handles this internally, so raw inflated values indicate the template is not applied or the wrong unit ID is in use.

The gateway connects but all registers return zero or unavailable. What now?

The most common cause is an incorrect unit ID. The GX device assigns a unit ID per connected battery based on its device instance, not a fixed value. Open the GX device interface, go to Settings, then Services, then Modbus TCP, then Available services, and locate the com.victronenergy.battery entry to find the correct unit ID for your battery.

History registers like deepest_discharge and charge_cycles return empty values on a CAN-bus battery. Is the template broken?

No. History registers such as deepest discharge, charge cycles, and mid-voltage are populated only by BMV battery monitors. CAN-bus BMS-connected batteries do not expose those fields over the com.victronenergy.battery service. The corresponding registers will return no data on BMS batteries; this is expected behaviour documented by Victron.

The time_to_go register reads zero. Does this mean the battery is empty?

A value of zero in the time_to_go register is a special case that means the battery is currently charging, not that runtime is exhausted. A genuinely low remaining runtime will return a small positive value. Cross-check with the soc register to confirm the battery state before raising an alert.

Free Modbus template: Victron Battery

Name: Victron Battery
Brand: Victron
SKU: 92721892-bbeb-4f21-9e14-7d422cc5b731

Victron Battery is a Modbus TCP template for battery monitors and CAN-bus BMS-connected battery systems integrated through a Victron GX device. The template covers the full com.victronenergy.battery register space: real-time readings for voltage, current, temperature, state of charge, and state of health; a comprehensive alarm set covering low and high voltage, temperature, cell imbalance, fuse, and charge current conditions; deep history data including cycle count, deepest discharge, and lifetime energy throughput; and BMS-reported charge and discharge limits. Use this template in ModbusCloud to centralise battery health monitoring across any Victron installation without custom scripting.

Registers (84)

84 read / 0 write

Name	Address	Function	Type	Unit	Access
voltage DC battery bank voltage in volts.	259	FC03	uint16	V	R
starter_battery_voltage Auxiliary starter battery voltage in volts.	260	FC03	uint16	V	R
current Battery current in amperes, positive when charging.	261	FC03	int16	A	R
temperature Battery temperature in degrees Celsius.	262	FC03	int16	°C	R
mid_voltage Mid-point voltage of the battery bank in volts.	263	FC03	uint16	V	R
mid_voltage_deviation Deviation of mid-point voltage from ideal balance.	264	FC03	uint16		R
consumed_amphours Amp-hours consumed from the battery since last full charge.	265	FC03	uint16		R
soc Battery state of charge, 0 to 100 percent.	266	FC03	uint16	%	R
alarm General alarm flag: 0 = no alarm, 2 = alarm.	267	FC03	uint16		R
low_voltage_alarm Low battery voltage alarm state.	268	FC03	uint16		R
high_voltage_alarm High battery voltage alarm state.	269	FC03	uint16		R
low_starter_voltage_alarm Low starter battery voltage alarm state.	270	FC03	uint16		R
high_starter_voltage_alarm High starter battery voltage alarm state.	271	FC03	uint16		R
low_state_of_charge_alarm Low state of charge alarm: 0 = no alarm, 2 = alarm.	272	FC03	uint16		R
low_temperature_alarm Low battery temperature alarm state.	273	FC03	uint16		R
high_temperature_alarm High battery temperature alarm state.	274	FC03	uint16		R
mid_voltage_alarm Mid-point voltage imbalance alarm state.	275	FC03	uint16		R
low_fused_voltage_alarm Low voltage alarm on fused battery connection.	276	FC03	uint16		R
high_fused_voltage_alarm High voltage alarm on fused battery connection.	277	FC03	uint16		R
fuse_blown_alarm Fuse blown alarm: 0 = no alarm, 2 = alarm.	278	FC03	uint16		R
high_internal_temperature_alarm High internal temperature alarm state.	279	FC03	uint16		R
relay_status Battery monitor relay state: 0 = open, 1 = closed.	280	FC03	uint16		R
deepest_discharge Deepest recorded discharge depth in amp-hours.	281	FC03	uint16		R
last_discharge Depth of the most recent discharge in amp-hours.	282	FC03	uint16		R
average_discharge Average discharge depth across all recorded cycles.	283	FC03	uint16		R
charge_cycles Total number of charge cycles recorded.	284	FC03	uint16		R
full_discharges Total count of full discharges recorded.	285	FC03	uint16		R
total_amphours_drawn Cumulative amp-hours drawn from the battery lifetime.	286	FC03	uint16		R
history_min_voltage Lowest battery voltage recorded in history.	287	FC03	uint16	V	R
history_max_voltage Highest battery voltage recorded in history.	288	FC03	uint16	V	R
time_since_last_full_charge Time elapsed since the last full charge event.	289	FC03	uint16		R
automatic_syncs Count of automatic synchronisation events performed.	290	FC03	uint16		R
low_voltage_alarms Cumulative count of low voltage alarm events.	291	FC03	uint16		R
high_voltage_alarms Cumulative count of high voltage alarm events.	292	FC03	uint16		R
low_starter_voltage_alarms Cumulative count of low starter voltage alarm events.	293	FC03	uint16		R
high_starter_voltage_alarms Cumulative count of high starter voltage alarm events.	294	FC03	uint16		R
min_starter_voltage Lowest starter battery voltage recorded in history.	295	FC03	uint16	V	R
max_starter_voltage Highest starter battery voltage recorded in history.	296	FC03	uint16	V	R
low_fused_voltage_alarms Cumulative count of low fused voltage alarm events.	297	FC03	uint16		R
high_fused_voltage_alarms Cumulative count of high fused voltage alarm events.	298	FC03	uint16		R
min_fused_voltage Lowest fused connection voltage recorded in history.	299	FC03	uint16	V	R
max_fused_voltage Highest fused connection voltage recorded in history.	300	FC03	uint16	V	R
dc_discharged_energy Cumulative DC energy discharged from battery in watt-hours.	301	FC03	uint16	Wh	R
dc_charged_energy Cumulative DC energy charged into battery in watt-hours.	302	FC03	uint16	Wh	R
time_to_go Estimated runtime remaining at current load; 0 means charging.	303	FC03	uint16		R
soh Battery state of health, 0 to 100 percent.	304	FC03	uint16	%	R
charge_max_voltage Maximum allowable charge voltage reported by BMS.	305	FC03	uint16	V	R
discharge_min_voltage Minimum allowable discharge voltage reported by BMS.	306	FC03	uint16	V	R
charge_max_current Maximum allowable charge current reported by BMS.	307	FC03	uint16	A	R
discharge_max_current Maximum allowable discharge current reported by BMS.	308	FC03	uint16	A	R
capacity_in_amphours Nominal battery capacity in amp-hours.	309	FC03	uint16		R
timestamp_1st_last_error Unix timestamp of the most recent error event.	310	FC03	int32		R
timestamp_2nd_last_error Unix timestamp of the second most recent error event.	312	FC03	int32		R
timestamp_3rd_last_error Unix timestamp of the third most recent error event.	314	FC03	int32		R
timestamp_4th_last_error Unix timestamp of the fourth most recent error event.	316	FC03	int32		R
min_cell_temperature Lowest individual cell temperature in degrees Celsius.	318	FC03	int16	°C	R
max_cell_temperature Highest individual cell temperature in degrees Celsius.	319	FC03	int16	°C	R
high_charge_current_alarm High charge current alarm state.	320	FC03	uint16		R
high_discharge_current_alarm High discharge current alarm state.	321	FC03	uint16		R
cell_imbalance_alarm Cell voltage imbalance alarm state.	322	FC03	uint16		R
internal_failure_alarm BMS internal failure alarm state.	323	FC03	uint16		R
high_charge_temperature_alarm High temperature during charging alarm state.	324	FC03	uint16		R
low_charge_temperature_alarm Low temperature during charging alarm state.	325	FC03	uint16		R
low_cell_voltage_alarm Low individual cell voltage alarm state.	326	FC03	uint16		R
victron_state Operational state of the Victron battery system.	1282	FC03	uint16		R
error Active error code reported by the battery or BMS.	1283	FC03	uint16		R
system_switch Battery system switch status, open or closed.	1284	FC03	uint16		R
balancing Cell balancing active flag: 0 = inactive, 1 = active.	1285	FC03	uint16		R
number_of_batteries Total number of battery units in the system.	1286	FC03	uint16		R
batteries_parallel Number of battery units connected in parallel.	1287	FC03	uint16		R
batteries_series Number of battery units connected in series.	1288	FC03	uint16		R
number_of_cells_per_battery Cell count per individual battery unit.	1289	FC03	uint16		R
min_cell_voltage Lowest individual cell voltage in millivolts.	1290	FC03	uint16	mV	R
max_cell_voltage Highest individual cell voltage in millivolts.	1291	FC03	uint16	mV	R
shutdowns_due_error Total count of shutdowns triggered by errors.	1292	FC03	uint16		R
diagnostics_1st_last_error Error code of the most recent diagnostic fault.	1293	FC03	uint16		R
diagnostics_2nd_last_error Error code of the second most recent diagnostic fault.	1294	FC03	uint16		R
diagnostics_3rd_last_error Error code of the third most recent diagnostic fault.	1295	FC03	uint16		R
diagnostics_4th_last_error Error code of the fourth most recent diagnostic fault.	1296	FC03	uint16		R
allow_to_charge BMS permission flag for charging the battery.	1297	FC03	uint16		R
allow_to_discharge BMS permission flag for discharging the battery.	1298	FC03	uint16		R
external_relay External relay state controlled by the battery system.	1299	FC03	uint16		R
history_min_cell_voltage Lowest cell voltage ever recorded in history.	1300	FC03	uint16	V	R
history_max_cell_voltage Highest cell voltage ever recorded in history.	1301	FC03	uint16	V	R

Victron Battery

Overview

Use cases

Installation

Things to watch for

Registers (84)

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