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krby avatar image
krby asked

Powering off BMV 7-series , what will I lose?

I have a Multiplus-II hooked up to LiFePO4 in a portable box. I'm considering replacing my DROK voltage readout with a BMV 7-series (likely the BMV 700) so I can actually track amp-hours in and out. This box isn't used often, it's for local power outages, camping, events, etc. So I hooked up one of those big red marine/RV round switches to connect/disconnect the battery from the Multiplus. The switch goes has OFF, Precharge, ON positions, giving me a pre-charge circuit to avoid the "big spark from capacitor charge up" problem.

Since I leave this box sitting for months at a time, I'd like to be able to completely turn it off, with a BMV-700 (and the others in the family) what info/settings do I lose if the BMV unit loses power? It would be great if amp-hours isn't lost, but I suspect it will be. If overall settings are lost, that's kind of a deal breaker.


Multiplus-IIBMV Battery Monitor
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2 Answers
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klim8skeptic answered ·

@krby The BMV 700 will defintly lose the SOC and probably the consumed Ah as well.

I would not recommend that a BMV 700 / 702 be left permanently connected to the battery, as it will consume 2.2Ah from the battery per month (more if the relay is active).

You could use a a BMV 712 and leave it permanently connected to the battery as it has a lower power consumption of only 720mA per month.

If you are OK using a phone app (Victron Connect) to connect to the monitor, a SmartShunt might be a better option, no display to get knocked around, and no buttons for ppl to fiddle with. The SmartShunt has 720mA power consumption per month, and a good option to be left permanently connected.

Always store your Li batteries with a near full SOC.

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krby avatar image
krby answered ·

Thanks for the feedback! I wanted to double check your numbers. I found these datasheets:
* 700-series: https://www.victronenergy.com/upload/documents/Datasheet-BMV-700-series-EN.pdf
* 712: https://www.victronenergy.com/upload/documents/Datasheet-BMV-712-Smart-EN.pdf

The 700-series are shown as having <4mA of current draw with the backlight off. That is 0.004A * 24hrs/day * 30days/month = 2.88Ah per month worst case, 2.12Ah is I assume 3mA instead of 4mA.

The 712 is shown as <1mA so 0.001A * 24 * 30 = 0.72Ah per month, likely a little under.

Just as you said, the 712 is much better for drain! Appreciate the tip, I would have missed that because I don't need need the Bluetooth connectivity. With this low level of draw, I'll just leave it connected all the time! If I'm doing the math right, with a 712, 24V 200Ah battery would get down to 50% in over 138 months!



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