How to connect the shunt SPF102MOD to the WatchMon

How to correctly connect the Shunt to the WatchMon1.


Raw parts

  • SPF102MOD from Sendyne Corp.
  • MOLEX 33472-0401 Connector Housing, Polarisation A, Black, MX150 Series, Receptacle, 4 Ways, 3.5 mm.
  • MOLEX 33012-3002 Rectangular Power Contact, MX150 Series, Tin Plated Contacts, Copper Alloy, Socket, Crimp, 20 AWG.

Recommended cabling used should be twin twisted pair (4 core) 20-24AWG multi-strain.

  • BELDEN 8723 060U500 Multipair Screened Cable, 2 Pair, 22 AWG, 0.325 mm².
  • Dekoron instrumentation cable IEC183AA004.
  • CAT5 network multistrand cable (not solid core).

Wiring to the shunt plug as follows:

Pin Colour Function
1 Black Isolated Ground
2 Orange Isolated TX outbound from Shunt to RX inbound  in WatchMon
3 Red Isolated 5vdc supply
4 Yellow Isolated RX inbound to Shunt from TX outbound of WatchMon

Molex connector wiring

  Molex Connector Assembly

The shunt needs to be installed on the negative terminal of the battery, pay attention to the orientation of the shunt. If the orientation is reversed the system will report charging when actually discharging. This can be corrected in configuration by enabling the reverse sensor state. As a rule of thumb the plug side of the shunt should be away from the negative battery terminal.

Photo below includes a latching contactor that can engage or isolate the battery when required.  

Connect the shunt positive sensor lead to the postitive of the pack, its best for this to be on the battery side of any contactors/ isolators such that the shunt is able to detect the battery voltage even when disabled. The shunt monitor does not consume power from the battery but is supplied from the WatchMon supervisor. 

The WatchMon terminal strip is connected as follows:

Pin Colour Function
12 Red Isolated 5vdc supply
13 Orange Isolated RX inbound  to WatchMon
14 Yellow Isolated TX outbound from WatchMon
15 Black Isolated Ground

NB: There are a number of shunt current options available, with the voltage sensor range adjustable. 

 When making cables for the shunt complete using the following steps:

Step 1 - Start with twisted pair cable

Step 2 - Adjust using wire strippers

Step 3 - wire stripped

Step 4 - add ferrells / boot lace

Step 5 - crimped and trimmed to length to attached to WatchMon

Step 6 - shunt end cable

Step 7 - prepare pins for shunt connector

Step 8 - push pins all the way to white connector

Step 9 - Completed connector

Step 10 - insert into the shunt

Step 11 - connector attached

Step 12 - connector and watchmon

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