Mastervolt 77020115 MasterShunt 500 CZone Battery Monitor

The Mastervolt MasterShunt 500 CZone is a high-accuracy digital battery monitor designed to measure and distribute essential battery-bank information throughout an integrated marine, mobile or off-grid electrical system. Installed in the main DC connection near the battery bank, it measures current flow, voltage, state of charge and estimated runtime, then shares that information with compatible MasterBus, CZone and NMEA 2000 equipment such as chargers, inverter/chargers, displays and system-control devices.

Key Features

• Monitors battery voltage, current, state of charge and estimated time remaining
• Supports MasterBus, CZone and NMEA 2000 communication
• Measures up to 300 amps continuously
• Handles 400 amps for 10 minutes, 500 amps for five minutes and 600 amps for two minutes
• Programmable alarms for low voltage, low state of charge and high voltage
• Integrated real-time clock supports timers and automated system events
• Can initiate compatible generator auto-start and stop functions
• Service mode helps preserve stored battery history during maintenance
• Multiple MasterShunt units can be installed in parallel for higher-current MasterBus systems
• Accepts optional Class T or ANL main fuses
• Includes insulated protection around the high-current DC connections

Application Compatibility

The MasterShunt 500 CZone is intended for battery-powered systems requiring accurate monitoring and integration, including:

• Recreational and commercial marine vessels
• Motor yachts and cruising boats
• Recreational vehicles
• Emergency and specialty vehicles
• Industrial battery systems
• Mobile workshops and service vehicles
• Off-grid and infrastructure power systems

One MasterShunt monitors one battery bank. Additional units are required when separate battery banks must be monitored independently.

Battery and Electrical Specifications

• Product version: MasterShunt 500 CZone
• Battery voltage: 12 or 24 volts DC
• Later hardware version K also supports 36- and 48-volt DC systems
• Voltage measurement range: 0–60 volts
• Current measurement range: 0–500 amps
• Continuous current capacity: 300 amps
• Ten-minute current capacity: 400 amps
• Five-minute current capacity: 500 amps
• Two-minute current capacity: 600 amps
• Voltage accuracy: ±0.6%
• Current accuracy: ±0.8%
• Maximum monitored battery capacity: 9,999 Ah
• Normal idle consumption: 23 mA
• Power-saving consumption with MasterBus off: Less than 1 mA
• Supported battery types: Flooded lead-acid, AGM, gel and lithium-ion
• Protection rating: IP21

Displayed and Shared Information

When connected to a compatible Mastervolt or CZone display, the MasterShunt can provide:

• Battery-bank voltage
• Charge or discharge current
• Consumed amp-hours
• Remaining battery capacity as a percentage
• Estimated operating time remaining
• Charger and inverter operating status
• Power Sharing information
• Battery alarms and special system events
• Historical battery information

A separate compatible display is required to view this information locally. The MasterShunt itself does not include a customer-facing display screen.

Communication Compatibility

The 77020115 version supports:

• MasterBus
• CZone
• NMEA 2000

This distinguishes it from Mastervolt part number 77020110, which is the MasterBus-only version. Confirm the vessel’s network type before ordering.

System Automation

The MasterShunt can send battery information and event commands to compatible connected equipment. Supported system functions can include:

• Low-voltage warnings
• Low state-of-charge warnings
• High-voltage alarms
• Timed events
• Automatic generator starting and stopping
• Charger and inverter control
• Load-management actions

Available automation depends on the connected MasterBus or CZone devices and the way the system has been configured.

Fuse Compatibility

The MasterShunt includes a solid bus bar as standard. An optional main fuse can be installed within the housing using either:

• Class T fuse
• ANL fuse

The fuse is not included and must be selected according to battery-bank short-circuit capacity, cable size, connected equipment and applicable marine electrical standards.

Mastervolt specifically identifies Class T fusing for systems with high available short-circuit current, including many lithium battery installations.

Dimensions and Weight

• Height: 5.9 inches / 150 mm
• Width: 5.9 inches / 150 mm
• Depth: 2.6 inches / 65 mm
• Weight: 1.5 lb / 0.7 kg
• DC terminal hardware: M8 bolts
• Protection rating: IP21

Included Components

Mastervolt lists the 77020115 package as including:

• MasterShunt 500 CZone
• Battery-temperature sensor
• MasterBus terminator
• Insulating cover for the DC connections
• One-metre Mastervolt-to-CZone drop cable
• DC terminal covers and connection hardware

Package contents should be checked before installation, particularly when purchasing older or previously opened stock.

Fitment Notice

Part number 77020115 is the CZone- and MasterBus-compatible MasterShunt 500. It should not be confused with part number 77020110, which does not include the same CZone interface.

Confirm the following before ordering:

• Battery-bank voltage
• Maximum continuous and surge current
• Battery chemistry
• Required network protocol
• Fuse type and rating
• Number of battery banks to be monitored
• Compatible display or control interface
• Available mounting space near the battery bank

Support for 36- and 48-volt battery banks depends on the MasterShunt hardware revision. Verify that the unit is hardware version K or later before specifying it for those voltages.

Installation Notes

Install the MasterShunt as close to the battery bank as practical. The shunt must be positioned so that all current entering or leaving the monitored battery bank passes through the measuring connection. Loads or charging sources connected directly to the battery side of the shunt will not be measured correctly.

Use heavy-duty battery cables with properly crimped terminals and keep the conductors as short as practical. DC cable size and fuse protection must be selected for the installation’s maximum current and cable length.

The unit should be installed in a dry, protected location. Its IP21 rating does not permit direct exposure to rain, spray, bilge water or washdown. Mastervolt requires a compatible CZone tee connector when integrating the unit into a CZone network; the tee connector is not included.

When This Product Needs Replacement

Inspect or replace the MasterShunt if:

• Battery readings remain inaccurate after recalibration
• Current or voltage values are missing or unstable
• The device repeatedly loses communication with known-good network equipment
• DC terminals or the internal bus bar show heat damage
• The housing or insulated terminal covers are cracked
• Moisture intrusion or corrosion is visible
• The unit no longer stores battery history or state-of-charge information
• Alarm or automation events fail despite correct system programming

Before replacing the unit, inspect the battery connections, network cable, terminators, fuse, temperature sensor and system configuration. Incorrect wiring or a device connected on the wrong side of the shunt can produce inaccurate battery readings.

Compatible Displays and Accessories

• Mastervolt EasyView 5 display – 77010310
• Mastervolt SmartRemote – 77010600
• Compatible CZone Touch displays
• MasterBus network cables and terminators
• Mastervolt-to-CZone drop cable
• Compatible NMEA 2000 displays
• Class T fuse and holder components
• ANL fuse
• Additional MasterShunt 500 units for separate battery banks or supported parallel installations

The MasterShunt 500 pairs well with the Mastervolt CombiMaster 12/3000-160 Inverter/Charger for a fully integrated MasterBus/CZone power system.

Alternate Part Numbers

• Mastervolt product code: 77020115
• Product name: MasterShunt 500 CZone
• Unspaced catalogue reference: 77020115
• MasterBus-only version: 77020110 — not directly equivalent

Parts Desk Insight

The MasterShunt 500 is more than a standalone battery gauge. It acts as the battery-information centre for an integrated Mastervolt or CZone system, allowing chargers, inverter/chargers, displays and generator controls to respond to actual battery conditions. The 77020115 version is the correct choice when CZone or NMEA 2000 integration is required in addition to MasterBus.