Adding a pin to the main connector


  • Hello, I am interested in using the signal relay1 - user defined  normally closed (pin 1) of the main connector. What are the specs and pin type I would need? My request is from the need to draw more than 700 ma through the relay circuits. I want to use a Blue Sea’s ML 7700-12 v latching battery switch device that draws up to 7 amps (very short duration about 20 ms per their data sheet) is there some way I can use my REC BMS 4S to do so directly? I’m not familiar on how to do that if even possible using the “Digital Outputs “ described in the manual.


  • Tine, can you help with inquiry please. @tine  

  • Thanks to Ben for finding this link and wiring diagram from Cruisers Forum. See attached wiring diagram In this configuration the power for switching is drawn from the red wire, not the orange and brown https://www.cruisersforum.com/forums/f166/merged-lifeypo4-1000ah-winston-prismatic-cells-and-all-electric-galley-201795.html

  • Thank you for the diagram, but I am looking to control the Blue Sea’s unit from the REC BMS. Can you help with that configuration?

  • TE Connectivity crimps 770854-1 may be used.  See ABMS manual for adding extra connections. There is a 3.15 A Slow blow fuse with a 2x3A @ 12 VDC internal relay. We do not recommend to drive 7A bi-stable latching relay directly since the small internal signal relay may weld together or the fuse may blow. A capacitor inverter circuit may be used as proposed or BSLCR driver + 2 relays since BLUE SEA use s different logic in opposite to open collector transistor coil drive inside the BSLDR.

  • I am running into this same issue.  Was planning to connect the Relay NC wire to drive the  bistable relay per the cruiserforum schematic . I am surprised the Relays NC wire was not populated in the wiring harness. This makes the job more difficult.

  • I found a solution for adding pins.  Since I am not using all the OPTO wires in the harness,  remove two of those and move them to the RELAY NC pins on the AMPSEAL connector.   Detailed Instructions on how to remove and insert wires/terminals into the harness can be found here: https://www.youtube.com/watch?v=K3d2u-a7udQ  

  • An even better solution is to use Blue Sea Systems 7713 or 7718 which operates like a Normally-Open RELAY,  instead of the 7700 which needs a special circuitry to connect.   It appears the 7713/7718 model has this circuitry built-in.

  • Thanks Blaine, very helpful information.

  • Regarding the 7amp  max draw when switching.  That current craw comes from the 15Amp fused power supply (red wire), *NOT* the NO (brown) or NC (orange) switch circuit.  So I don\'t think the BMS internal relay will be at risk of overload.

  • Quote from Blaine Kubesh on February 23, 2021, 7:38 pm
    Regarding the 7amp  max draw when switching.  That current craw comes from the 15Amp fused power supply (red wire), *NOT* the NO (brown) or NC (orange) switch circuit.  So I don\'t think the BMS internal relay will be at risk of overload.
    With the 7713 the power to switch comes from the main input 3/8 lug as per Blue Sea tech support.  The BMS will only see a 13mA load when holding the 7713 in the closed state.  

  • Does anyone have a wiring diagram for the ABMS and the REC BSLRD  and the Blue Sea 7713? thanks  

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