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MPPT & Multiplus Dual Charging & avoiding overcharge

Greetings,

Could only find a single post on this topic. So I have a Multiplus 12/3000/120 and a MPPT 100/50 newly installed in my travel trailer.

What is the best way to go about configuring the chargers that avoids overcharging the batteries when both solar is available and shore power on the Multiplus? I am fearful of overcharging the batteries when both units have available power for charging.

Only thread I found mentioned disabling one of the chargers. I find this to be a poor solution as I do NOT want to have to manually monitor the chargers and remember when to turn them on or off. I would expect Victrons products to be intelligent enough to not overcharge when both sources are available but that's more hope than reality at this point. Please help! Thanks!!



MultiPlus Quattro Inverter Chargerbattery chargingmppt charging
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WKirby answered ·

You can have multiple chargers all acting independently if you like. To prevent overcharging, you simply make sure that they are all aiming for the same Absorb Voltage and Absorb time.

Once the absorb Voltage is reached then the charging current will back off to maintain the Voltage eg 14.8V. Independently, they won't synchronise perfectly, one may switch to float slightly arlier than the other and one may charge with more current than the other, but if the settings are the same then overcharging should not occur.

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Sportswagoneer answered ·

I’ve ben wondering about this...

With a 3x100A LFP BMS, limiting charge current in general is irrelevant. My objective would be to limit the total absorption time when my boat is connected both to shore power and an active MPPT charger during the week.

Currently, the MPPT will run through one or more Bulk-Absorption-Float cycles each day. I’d like to limit this to say once a week.

As far as I have researched the GX options, they say ”Don’t use ESS for marine applications” while the DVCC requires an active ESS to take control of the MPPT charging cycles (rather than just current limiting them.) Am I trying to solve a non-problem or am I missing something in the system manuals?

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Currently, the MPPT will run through one or more Bulk-Absorption-Float cycles each day. I’d like to limit this to say once a week.

Not really.

Your Mppt will go through a full bulk>absorb>float charge cycle once per day.

Should the battery voltage fall lower than float voltage (minus rebulk voltage) the mppt will attempt to charge the battery back to the absorb voltage.

If the battery gets back to absorb voltage, the mppt will go to float. Thats good.

If the battery fails to get to absorb voltage, there is probably not enough energy to harm the battery. Thats ok.

Should the solar harvest be bad enough that the mppt restarts several times a day, that sucks. Not enough energy to harm battery.

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customfab answered ·

Thanks WKirby. Exactly what I did and my manual monitoring shows both seem to be working together well.

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klim8skeptic answered ·

If you have a GX device, DVCC can be used to set a "limit charge current".

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