question

Wildebus avatar image

BMV-712 stays 'alive' with Aux Power signal?

Simple question I think?

On the BMV-712, If the auxilary input, used for the Starter Battery, is at 12V, will the BMV still work and keep all the current data if the main power input is removed? So when the Main input is back, it will carry on where it left off in terms of data?


Unfortunately I didn't think to check this before I started a couple of battery discharge tests, and which I am now in the middle of so cannot check this with either of my BMV-712s in case the answer is no and I loose the SOC and Ahs used info when power is re-established.

(I am doing a full discharge test on a LiFePO4 until the BMS cuts out so expect to have the 12V cut out at some time)

BMV Battery Monitor
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Interesting situation. Please post the outcome! :)

4 Answers
Wildebus avatar image
Wildebus answered ·

Oh, I better close the loop on this ...

When the Main Battery cut out due to the BMS turning it off, the BMV turned off as well despite the Starter Battery being connected to Aux. So it is powered only by the Primary connection.

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Mark avatar image
Mark answered ·

From what I recall the BMV does not power up or remain powered from the aux voltage connection.

I actually power up the aux connection first to avoid an incorrect min aux voltage reading once the main power is connected.

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Shame that seems to confirm what I didn't want to hear, but a good idea there. I shall remember to do that in future.

Daniël Boekel (Victron Energy Staff) avatar image
Daniël Boekel (Victron Energy Staff) answered ·

Hi @Wildebus

I think it does, but not 100% sure...

edit: this answer proofed to be wrong.

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Wildebus avatar image
Wildebus answered ·

Well, I guess I am gonna find out in a few days! (unless someone out there has a 712 they could check and post?)

I'll connect the aux up to the starter anyway just in case it does stay powered.

I will have the data on the Venus GX (and so VRM) - but will need to switch that to power that from the Aux battery first or that will die as well of course! :)

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