Leveraging the SOC State for the BMV-712

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keithd311 asked Oct 10, '19

Leveraging the SOC State for the BMV-712

I am new to using the BMV-712 monitor and was hoping to be able to use the SOC percentage display to usable battery capacity in my RV installation. I would like to have the SOC measurement on the screen to show the value for the usable battery capacity - meaning with my lead acid battery, I am only able to use up to 50% of the battery before it needs to be recharged in order to prevent damage to the battery. With the current settings on my monitor, it shows a SOC value of approximately 50% when the battery charge is half used up. Is there a way to set the BMV-712 so the SOC at 50% battery charge would show 0% SOC? I know there is a small battery "fuel gauge" on the display as well, but SOC would be easier to read.

Thanks in advance for any help!

SOC

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edgargw22 commented · Oct 15, 2019 at 09:54 PM

following...

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Answer 1 · 2019-10-16T06:11:04Z

wkirby answered · Oct 16, 2019 at 06:11 AM

You could halve the battery capacity setting in the configuration. Setting this to 100Ah for a 200Ah battery would have the effect of showing 0% when 100Ah has been taken from a 200Ah battery - for example.

This does present a new set of problems. If you discharge beyond this 0% point then you have no idea you're doing it or by how much. Also when you do start to charge again the BMV will start counting up right away. Let's say you accidentally discharged to a real 40% SOC, you will only see 0%, not -10%. When charging again, and the BMV shows 1% you actually be at 41% not 51% and the whole thing goes out of sync.

It's better to measure the actual battery capacity and stop discharge when the BMV shows 50% to give you a true measure of the SOC of your battery.

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keithd311 commented · Oct 16, 2019 at 06:27 PM

Thanks you for the answer. Was hoping there was a setting I was missing somewhere. I don't want to add another level of complexity, so I will train my eyes to watch the fuel gauge and know that 50% SOC really means Zero! Thanks for the out of the box thinking!

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