# BMV-712 Smart Battery Monitor RJ12 Cable

**URL:** <https://community.victronenergy.com/t/bmv-712-smart-battery-monitor-rj12-cable/46967>\
**Category:** DIY\
**Tags:** bmv, marine\
**Created:** [13 October 2025 16:30 UTC](https://community.victronenergy.com/t/bmv-712-smart-battery-monitor-rj12-cable/46967 "2025-10-13T16:30:01Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![Tartan33R](https://avatars.discourse-cdn.com/v4/letter/t/e495f1/32.png) [@Tartan33R](https://community.victronenergy.com/u/Tartan33R)\
**Post date:** [13 October 2025 16:30 UTC](https://community.victronenergy.com/t/bmv-712-smart-battery-monitor-rj12-cable/46967/1 "2025-10-13T16:30:01Z")

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I’m wondering what the electrical characteristics are on the RJ12 cable connecting the shunt and display on the BMV-712. It appears to power the display, so part of it must be analog. Is the current signal digital or analog?

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**Author:** ![MikeD](https://dub1.discourse-cdn.com/victron/user_avatar/community.victronenergy.com/miked/32/1522_2.png) [@MikeD](https://community.victronenergy.com/u/MikeD)\
**Post date:** [13 October 2025 19:02 UTC](https://community.victronenergy.com/t/bmv-712-smart-battery-monitor-rj12-cable/46967/2 "2025-10-13T19:02:10Z")

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The data connections are digital, TTL serial data. The protocol can be found in the Victron technical documents.

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**Author:** ![Tartan33R](https://avatars.discourse-cdn.com/v4/letter/t/e495f1/32.png) [@Tartan33R](https://community.victronenergy.com/u/Tartan33R)\
**Post date:** [13 October 2025 23:47 UTC](https://community.victronenergy.com/t/bmv-712-smart-battery-monitor-rj12-cable/46967/3 "2025-10-13T23:47:59Z")

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A replacement PCB for the BMV-712 shunt is \<$30. At that price, I have a hard time believing that there could be a microprocessor on there doing analog to digital conversion and sending serial data out the RJ12 port. I looked through the Victron technical documents and what I found was in reference to VE.Direct, which is the port on the display, not the shunt.

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**Author:** ![UpCycleElectric](https://dub1.discourse-cdn.com/victron/user_avatar/community.victronenergy.com/upcycleelectric/32/36895_2.png) [@UpCycleElectric](https://community.victronenergy.com/u/UpCycleElectric)\
**Post date:** [14 October 2025 00:16 UTC](https://community.victronenergy.com/t/bmv-712-smart-battery-monitor-rj12-cable/46967/4 "2025-10-14T00:16:37Z")

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IIRC (If I Recall Correctly)  
Not much on the PCB, two caps and two fuses (description in the archived forum somewhere) with 6 wire for (in no particular order):

- Batt+ Power supply
- Batt+ Voltage sense
- 2nd Batt+ Voltage sense / Midpoint Voltage sense / Temp sensor (BMV specific)
- Current sensor-
- Current sensor+
- GND / Batt-

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<div class="post-metadata">

**Author:** ![Tartan33R](https://avatars.discourse-cdn.com/v4/letter/t/e495f1/32.png) [@Tartan33R](https://community.victronenergy.com/u/Tartan33R)\
**Post date:** [15 October 2025 23:46 UTC](https://community.victronenergy.com/t/bmv-712-smart-battery-monitor-rj12-cable/46967/5 "2025-10-15T23:46:29Z")

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Pictures of the PCB seem to confirm that there is no signal processing occurring at the shunt level.

 ![PCB BMV 702_712](https://europe1.discourse-cdn.com/victron/original/3X/1/8/183ca1719e77e0ac2ad85fc0dc23deca9b5ca9c6.jpeg)

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<div class="post-metadata">

**Author:** ![MikeD](https://dub1.discourse-cdn.com/victron/user_avatar/community.victronenergy.com/miked/32/1522_2.png) [@MikeD](https://community.victronenergy.com/u/MikeD)\
**Post date:** [6 August 2026 05:20 UTC](https://community.victronenergy.com/t/bmv-712-smart-battery-monitor-rj12-cable/46967/6 "2026-08-06T05:20:13Z")

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All analogue. uV reading from the shunt resistance on 2 pins, supply V1,V2 and gnd on 3 others.