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doublebubble avatar image
doublebubble asked

BMV 700 & MPPT SETTINGS

Just some advice please, we have an 800ah battery bank, three sets of solar panels with there individual Victron mppt's and a Victron BMV700, 12/3000/120 Multiplus, half way through the day all three mppt's go into float but the BMV700 still says 93% charged with a -65amps, when we run our generator with the Multiplus in charge mode it will go into float so I assume the batteries are full, but the BMV700 still reads 93 to 95% charged, can anybody advise on what settings to adjust in the BMV so everything is synced together.

BMV Battery Monitor
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JohnC avatar image JohnC ♦ commented ·

Hi @doublebubble

Without knowing what your batteries are it's impossible to recommend anything. Also your "-65amps" is a puzzle?

Your batts are only full when they can't accept much current, so don't assume SOC is correct until you've tuned in the BMV.

Can you supply screenshot of existing settings?

Familiar with the manual? https://www.victronenergy.com/upload/documents/Manual-BMV-700-700H-702-712-EN-NL-FR-DE-ES-SE.pdf


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doublebubble answered ·

Thanks for the reply John, the batteries are 4 x Lifeline GPL-16T 6v connected in parallel with a total of 800ah, the batteries are now 12mths old with our last set lasting over 12yrs, the mppt's are 2 x 100/30 and 1 x 75/15 for their own separate panels, as described above I noticed the other day that the mppt's were in float mode with the batteries being at 13.9v and not putting in any considerable charge so it would seem that the BMV would never get to 100%, here are some shots of the settings, note that it's showing full charge noq as we are back in the marina on shore power, all mppt's are set for battery life. The pictures are of the BMV settings and the 100/30 mppt whicch the other two mppt's have the same settings.screenshot-20201206-075016.jpgscreenshot-20201206-074928.jpg


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JohnC avatar image
JohnC answered ·

@doublebubble

Yeh, that's better. Can see now, twas dark before.. :)

Your BMV isn't synchronizing because it's Charged Voltage is set higher than the mppt Float V. Try lowering it to (say) 0.3V lower than Float, so 13.5V. Now it can sync to 100% while in Float.

But it may sync too early now with that default Tail set to 4%, which for you is 32 Amps. This is actually quite important, and you need to ask yourself whether you consider your batts are really charged to 100% when they can still accept 32A at float V. It depends on the battery characteristics to a degree, and other practical things like length of day, temp, and suchlike. I use 0.5%, but that may be too low for you, and that's what you need to determine.

Also, if you find your SOC trending downwards each day, having synced to 100% the day before and needs syncing upwards daily, you could raise the Charge Efficiency Factor a little. You can go too far with this of course, and you'll know that when it shows 100% and still accepting charge higher than you've decided as a practical level.

Have a go, and come back as you need.



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doublebubble answered ·

Thanks John very helpful, I'll have a play around and see how it goes.

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