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Robbo1_5@hotmail.com avatar image

Victron bmv712 incorrect SOC

Hi Guys

So ive got a victron bmv712. Running my canopy battery.

Have a bcdc redarc grounded on system grounds along with all loads.

Battery is lifepo4 150ah.

Yesterday i drew 33ah over night and 76% Soc assuming it would take a other 33ah to top back up. Had in sun for about 1hr and SOC was 100%?

How is this the case?

All wiring has been looked at thinking maybe something in settings might fix or voltage on bcdc an issue?


Help.


Thanks guys

BMV Battery Monitor
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2 Answers
Mark avatar image

I think that you have the sync parameters set too 'relaxed' for a solar setup - so the BMV auto resets to 100% SOC before the time when it is truely recharged to 100%.

Increase the 'charged voltage' setting to ~0.2v to 0.4v under the MPPT 'absorption voltage'. Also decrease the tail current % to ~2.5%, but also make sure that the MPPT settings charge the battery sufficiently to satisfy these thresholds.

The other parameters related to SOC tracking also seem to be incorrect for lithium.

Also take look at these BMV setup videos;

https://youtu.be/yMJ_vzB2avE

https://youtu.be/4ReljfO3k6M

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osaether avatar image

The BMV-712 synchronizes and calculates the SOC based on several factors; battery voltage, tail current, Peukert factor and so on. You might need to adjust these parameters. See section 2.2 Synchronizing the BMV in the manual.

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These are my settings


Does the unit need a couple of cycles to synchronise properly

Robbo avatar image Robbo Robbo1_5@hotmail.com ·

Charge efficiency on LFP's should be set to 98/99%, tail current 2-4%, charged voltage should be set around 0.3v below your absorbtion voltage.