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Brad Carpenter avatar image
Brad Carpenter asked

Can the BMV-712 relay be set to turn off only on battery charge and NOT temperature?

I'm trying to use the relay to turn off an accessory circuit only on battery state of charge, and not temperature. I see the manual notes referencing a CHRG mode for the BMV relay mode in section 7.3.1, which seems to exclude the temperature settings of the BMV-712 Relay Default mode.

However, when I tested the BMV-712 on CHRG mode, the relay still turned off with the temperature settings. I could not tell a difference between CHRG mode and Default mode.


Has anyone else had this issue? Is this a bug, is there another setting I need to change, or do I need to reset/reboot the system for these types of changes?

From the manual:
"CHRG
Charger mode.


The relay will close when the state of charge
falls below setting 16 (discharge floor) or when
the battery voltage falls below setting 18 (low
voltage relay). The relay will be open when the
state of charge is higher than setting 17 (clear
state of charge relay) and the battery voltage is
higher than setting 19 (clear low voltage relay).
An application example is to start and stop
control of a generator, together with settings
14 and 15."

BMV Battery Monitor
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4 Answers
kevgermany avatar image
kevgermany answered ·

If you look at 4.2.2 it becomes clearer. Charger mode adds 14 and 15. Guessing you have something in the temperature settings, 26-29 which is causing the combined effect. I assume you have the correct temp sensor wired to the battery positive.


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klim8skeptic avatar image
klim8skeptic answered ·

Have you tried 11~default and setting 16, 17~SOC at your soc targets?

11~CHRG adds in voltage targets on top of the soc targets.

12~invert relay might have to be flipped.

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Brad Carpenter avatar image
Brad Carpenter answered ·

Thanks Kevgermany for replying quickly.

Yes, I have a Victron temperature sensor connected to the battery and shunt with temperature settings to stop below-freezing temperature charging. However, I wanted to use the BMV-712 Relay to turn off electronics only with respect to battery voltage, but I see a combined effect for both SoC and Temp settings. I'm assuming from your post that the BMV relay will always look at temperature settings in either Default or Charger Mode.

I don't see section 4.2.2 in the "Manual - BMV-712 Smart" as you mention. I'm looking at the BMV manual Rev 10 - 12/2022. Has the reference to 4.2.2 for the BMV-712 you mention moved/been changed?

Also, do you know of a work around in the settings, or do I need to abandon my use of this relay?

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kevgermany avatar image kevgermany ♦♦ commented ·
Sorry for the confusion, I was working off a downloaded pdf, but seems it's been superceded and improved.

It's a single relay that will operate for any of the settings it's configured for, singly or in conjunction.

@klim8skeptic suggestion about alarms is the best way. But using them will be difficult.



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Brad Carpenter avatar image Brad Carpenter kevgermany ♦♦ commented ·
Thanks! I have found that the Charge Controller temperature setting is really the temperature I should be relying on, so I've changed my design to use the BMV-712 temperature settings for only the electrical accessories circuit.
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Brad Carpenter avatar image
Brad Carpenter answered ·

klim8skeptic I have tested the State of Charge (SoC) limits/voltage once, and it worked as planned. However, I wanted the BMV Relay to function only on SoC and NOT on temperature, but still let the BMV-712 tell the charge controller (not connected to the Relay) to stop charging with respect to temperature limits I set. I wanted a relay that only looked at SOC/voltage.

I'm assuming this is not what the BMV relay is designed to do/maybe it's a feature I need to request.

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klim8skeptic avatar image klim8skeptic ♦ commented ·

If you dont want the temperature to control the relay, turn it off. That will disable temp control of the relay, still allow temp alarms and temp readings.

screenshot-20230104-111114.jpg

If you dont have a temp sensor, set the aux port to none in the misc settings. if you do this the relay temp settings disappear (?).

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screenshot-20230104-111114.jpg (155.1 KiB)