question

wrnoof avatar image
wrnoof asked

MPPT on bulk when Quattro on storage.

Our Quattro is now at this instant charging in storage mode, but our BlueSolar is charging at bulk. Is this OK?

MPPT ControllersMultiPlus Quattro Inverter Charger
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Mike Dorsett avatar image Mike Dorsett commented ·
please can you provide more details about your system? If using parallel, independent chargers, then they both need to be set to the same voltage points.
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wrnoof avatar image wrnoof Mike Dorsett commented ·

The solar and MPPT were installed by the new boat dealer. So, I don't know the exact arrangement. I assume the Quattro and MPPT are parallel for charging the AGM house bank. I can't think of another arrangement for having dual chargers for the same bank.

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1 Answer
Justin Cook avatar image
Justin Cook answered ·

This is expected behavior, yes. The MPPT doesn't have a storage mode, instead starting every day with a new charge cycle, and the Quattro won't pop out of storage mode until the battery bank voltage drops below the rebulk voltage threshold (or until it's time for its refresh charge), which the bank probably won't fall to since it's being recharged by the MPPT.

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wrnoof avatar image wrnoof commented ·
I was thinking the MPPT would shift to float rather than stay in bulk. I think bulk voltage is higher than float or storage. Is there any danger of damage to the AGM batteries?
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Justin Cook avatar image Justin Cook ♦♦ wrnoof commented ·
The MPPT determines its charging schedule based on the battery voltage, so as long as it was programmed properly it's doing what it should!
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wrnoof avatar image wrnoof Justin Cook ♦♦ commented ·

Programmed properly may be an issue. The Quattro was installed by Dufour and the MPPT at the dealer in Annapolis. The two may not have communicated. I assume the Quattro uses the default charging profile: absorbtion @ 14.4v for up to 8 hrs, float @ 13.8v and storage @ 13.2v. This profile matches the default settings on the MPPT for absorption and float. The MPPT, however, is not set for the default but at switch position #3 or AGM spiral cell: absorption @ 14.7v and float @ 13.8v.


Should I use Victron Connect to switch the MPPT to the default setting? I am in Denver, and the boat is in BVI. So, I won't be around to monitor the results like overheating, etc. Also, the boat's batteries are not holding a charge, and, while sailing, the voltage drops below 13.4v (13.8v float less 0.4v rebulk offset). When that happens, the MPPT slips into bulk mode and will stay there until the absorbtion voltage, 14.7v under the current profile, is reached. Since the Quattro flips to absorption at 14.4v, the MPPT never gets to the 14.7v absorption threshold and is stuck in bulk. I suspect I should change the MPPT to the default profile and get new batteries.

I am wondering whether this likely mismatch between the Quattro and MPPT charge profiles has accelerated the demise of the batteries. Thanks for your help and advice. It's great.


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