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daviddp asked

Setup BMV 700 for lithium batteries


I have a BMV700 monitor and lithium batteries, but the monitor is showing the batteries are at 100% state of charge before they are really fully charged I have charged the batteries until the charger shuts down and reset the monitor so it knows full soc and it will give me a % reading while the batteries are discharging, but in the morning when the sun comes up the monitor will show 100% within an hour.

Is there a setting I need to change on the monitor for lithium, or charge rate so it will give me an accurate reading.

Regards David

BMV Battery MonitorVEConfigure 3installation
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1 Answer
Mark avatar image
Mark answered ·

First thing that I would check is if you have correctly entered in the battery bank capacity / Ah (20h discharge rating).

If this is correct, then you might have the sync parameters set too low / wide. For solar I would set the sync voltage to be about 0.2 to 0.4 below absorption voltage, the tail current percentage to ~2 to 4% & the time to ~2 to 5 min.

Other than this, for lithium the peukert exponent should be ~1.05 & the charge efficiency ~98 to 99%.

If you still have trouble, post up some screen images of your MPPT settings, MPPT history & BMV settings so that we can review.

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daviddp avatar image daviddp commented ·

Thanks Mark

I checked the controller settings and below is what I had it set at.

Batetery capacity - 300ah

Tail current - 4

Charge tetection time - was set at 10min I have now changed to 4

Peukert exponent - 1.05

Charge efficiency - 99%.

My solar charger is a Victron mpg 150/45 but I don’t have the Bluetooth so can’t get any screen shots for you, would you recommend that I purchase the Bluetooth dongle.

Regards David

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Mark avatar image Mark ♦♦ commented ·

What about charged voltage?

It's best to set this to just below absorption voltage.

About your MPPT, if you are using the rotary preset dial to select the charge curve then you can check the voltages in the manual. But yes a Bluetooth dongle would be helpful.

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