SC303 & SC503 Digital Shunt User Manual

Version: V1.3

1. Introduction

Simarine's high precision SCX03 (SC303 & SC503) active digital shunt measures voltage, current and temperature of the battery or battery bank.

It can be used for monitoring current draw of heavy consumers (inverters, bow and stern thrusters, anchor winches) and current generators (shore power chargers and solar panels). Additionally, it allows monitoring tanks for fuel, fresh and grey water.

Innovative combination of shunt and tank level module. SC303 is an active combo shunt for PICO battery monitor with 2x voltages, 2x tank level or temperature, 1x socket for temperature sensor with JST connector and 1x current sensor up to 300A for up to 75V systems. It can be used for monitoring current draw of heavy consumers (inverters, bow and stern thrusters, anchor winches) and current generators (shore power chargers and solar panels). Additionally, it allows monitoring tanks for fuel, fresh and grey water. SC303 is capable of measuring continuous current up to 300 A and suitable for maximal power of 3600 W at 12 V or 7200 W at 24 V
Innovative combination of shunt and tank level module. SC503 is a high precision combo shunt for PICO battery monitor with 2x voltage, 2x temperature, 1x socket for temperature sensor with JST connector and 1x current sensor up to 500A for up to 75V systems. SC505 is capable of measuring continuous current up to 500 A and suitable for maximal power of 6000 W at 12 V or 12000 W at 24 V.

2. Safety

Electrical specialists with proper safety equipment should make installation of Simarine electronics. When working with batteries, you should wear protective clothing and eye protection.

CAUTION: Batteries contain acid, a corrosive, colorless liquid that will burn your eyes, skin, and clothing. Should the acid come in contact with eyes, skin or clothing, wash it immediately with soap under fresh water for at least 15 minutes, and seek medical support immediately.

CAUTION: Do NOT connect anything to a damaged battery. It could heat up, catch fire or explode.

CAUTION: Lead-acid batteries can generate explosive gases during operation. Never smoke, allow flames or sparks near the battery. Make sure to keep sufficient ventilation around the battery.

3. Overview

The SC503 unit features the following ports and connections:

A - Battery Input Side
B - System Output Side
C - 2x SiCOM port
D - 1x JST socket for temperature sensor
E - 2x Voltage & 2x Resistance input

4. Installation

CAUTION: Install the shunt module in a clean dry place, protected from accidental spilling of liquids.

Remove the shunt cover by unscrewing four screws on top of the shunt cover.
To install the shunt, use the supplied voltage cables and find a place no further than 3 m away from the battery/battery bank. You can fix the shunt with the supplied screws using two holes on the bottom of the casing.
Connect all cables.
Place back the shunt cover and screw the four screws on the cover of the shunt unit.

4.1 Cables

For the SiCOM connection, use the supplied cable. If not possible, use the following table to determine the right cable type:

Cable length	Cable type
< 5m	No limitations
>= 5m	2x2x0.25 mm² Twisted pair (recommended)

4.1.1 Power cable

Minimum power cable cross-section requirement at maximal temperature of insulation 70 °C (160 °F).

Continuous current	Area
500 A	220 mm²
400 A	150 mm²
300 A	95 mm²
200 A	50 mm²
100 A	25 mm²

CAUTION: Failure to observe the required cable cross-section can damage the shunt, wiring, or cause a fire.

5. Connecting

For proper function of Simarine's SC303/SC503 digital shunt, it is necessary to take the following steps:

Disconnect the battery/battery bank plus and minus terminal, for safety reason.
Connect the shunt to Simarine's PICO via the SiCOM port.
Connect shunt voltage sensing input to a battery terminal.
Connect the temperature sensor to the shunt and place it near the battery/battery bank (optional).
Connect batteries/batteries bank minus or plus terminal through the shunts IN terminal.
Connect all consumers and charging sources to the OUT terminal on the shunt.

Each correctly connected shunt needs to be configured. This is done via PICO in an easy way. The configuration process is described in PICO's manual.

• PICO manual & other user manuals: https://simarine.net/manuals

It is recommended that the shunt is installed in the negative line if possible.

CAUTION: After connecting the shunt, make sure that all the connections between cables and shunt are tight. Loose connections may cause sparks, heating and even a fire. It may also damage the shunt.

5.1 SCX03 installed on the minus terminal of the battery

Diagram illustrating the connection of the Simarine SCX03 shunt to a PICO battery monitor. The PICO unit is connected to the SCX03 shunt via a SICOM port. The SCX03 shunt has terminals for voltage inputs (U1, U2), ground (GND), resistance/temperature (R1, R2, NTC), and a JST socket for a temperature sensor. The diagram shows the shunt installed on the negative terminal of the battery bank. Connections are made from the battery to the shunt's 'IN' terminal and from the shunt's 'OUT' terminal to a switch panel distributing power to various loads such as a refrigerator, lights, inverter, autopilot, and other nautical instruments. Optional connections for tank level sensors (voltage or resistance type) are also indicated. The diagram also shows connections for accessory and ignition switches.

6. Technical specifications SC303 & SC503

SC303

Parameter	Value
Operating Voltage range	6 – 35 V
Temperature range	-20 – 70°C (-4 – 158 °F)
Power consumption at 12V	0.8 mA
Current Measuring range Per channel	0.01 - 320 A
Accuracy	± 0.6 %
Resolution	0.01 A
Sampling rate	100 ms
Maximal current Continuous	300 A
Peak current (<1min)	700 A
Peak current (<5min)	400 A
Voltage drop at 300 A	50 mA
Maximal voltage on connections	35 V
Voltage inputs Range	0 - 75 V
Accuracy	± 0.2 %
Resolution	1 mV
Sampling rate	100 ms

Parameter	Value
Resistance inputs Range	0 Ohm - 65 kOhm
Accuracy	± 3 %
Temperature sensor - NTC 10k Range	-15 – +80 °C
Accuracy (-10 – 60 °C, 14 – 140 °F)	± 3 %
Connectivity	Up to
Batteries	1
Temperature sensors	3
Voltage sensors	2
SiCOM RJ9 Sockets	2
Installation and Dimensions Dimensions	120 x 120 x 60 mm 4.72 x 4.72 x 2.36 in
Battery connection	M 10 bolts

SC503

Parameter	Value
Operating Voltage range	6 – 35 V
Temperature range	-20 – 70°C (-4 – 158 °F)
Power consumption at 12V	1.2 mA
Current Measuring range Per channel	0.01 - 700 A
Accuracy	± 0.6 %
Resolution	0.01 A
Sampling rate	100 ms
Maximal current Continuous	500 A
Peak current (<1min)	1000 A
Peak current (<5min)	700 A
Voltage drop at 300 A	50 mA
Maximal voltage on connections	35 V
Voltage inputs Range	0 - 75 V
Accuracy	± 0.2 %
Resolution	1 mV
Sampling rate	100 ms

Parameter	Value
Resistance inputs Range	0 Ohm - 65 kOhm
Accuracy	± 3 %
Temperature sensor - NTC 10k Range	-15 – +80 °C
Accuracy (-10 – 60 °C, 14 – 140 °F)	± 3 %
Connectivity	Up to
Batteries	1
Temperature sensors	3
Voltage sensors	2
SiCOM RJ9 Sockets	2
Installation and Dimensions Dimensions	120 x 120 x 60 mm 4.72 x 4.72 x 2.36 in
Battery connection	M 10 bolts

7. Troubleshooting

7.1 Negative current values

If PICO is showing the wrong sign for current value, check if the shunt is correctly installed. This means the battery/battery bank minus (optionally plus) terminal is connected to the IN terminal on the shunt. If this is not the case, you can reinstall the shunt or simply switch the IN and OUT terminal via the shunt configuration on PICO.

7.2 Shunt is not visible on PICO

If the shunt is not visible on PICO's menu, check the following:

Is the shunt properly connected via the SiCOM port to the PICO
If you are using your own SiCOM cable make sure it has the right square and is twisted.
Check if the voltage sensing input is correctly installed and doesn't have the plus and minus terminal switched

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