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Tom avatar image
Tom asked

BMV-712 State of Charge

I have a BMV-712 monitoring (3) SuperPack 200Ah Victron Batteries.

Currently, the phone app is showing the batteries have an 82% state of charge but the voltage is 12.94V. I talked with tech support where I purchased the batteries and have confirmed that the BMV is setup correctly and that I need to use the batteries for the BMV to accurately indicate state of charge. We have been living in our van for more than month.

Why is the BMV showing 82% state of charge but the store where I purchased the batteries noted that the DC Input low alarms pre-alarm for the attached Multiplus should be set at 12.0v and DC Low Input-shutdown is 11.80?

Thank you!

BMV Battery MonitorSuperPack
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Ulrich avatar image
Ulrich answered ·

Hello Tom,

The BMV-700 not only calculates the state of charge from the voltage, it also measures the incoming and outgoing current. Since your battery needs more than 100% current to reach a state of charge of 100%, you have to set the BMV-700 very precisely. There are a lot of videos from Victron Energy on their YouTube channel (https://www.youtube.com/channel/UCMWYxDjwpyQGw6zg5p9SNhw).

All devices must of course be set to the correct battery type.

Please make sure that all cable cross-sections are sufficiently dimensioned and that all lengths between all batteries and the busbar are the same length. The inverter and the solar charge controller must be connected to the busbar.

I hope I was able to help you, if you have any questions, I'll be happy to help you.

greetings

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Tom avatar image Tom commented ·

Thank you Ulrich...I appreciate the advice. Right after I posted this I found the Victron YouTube Channel and I have watched the videos associated with the BMS-712.

All of the cable lengths are the same and I verified cable cross sections with the retailer prior to the installation of our third battery. Batteries, MPPT, Multiplus, Cyrix-Li-CT and BMS are connected to the same busbar.

Shore power is connected to the Multiplus which is connected to the busbar. I do notice that when charging off shore power, voltage reaches 14.2V but when charging via the Cyrix-Li-CT or solar/MPPT voltage hovers around 13.5v with 100% capacity. Do you have some thoughts on the why two voltage levels are different?


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