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How to set up MPPT correctly.

I’m new to solar, but my RV has panels and a large AGM battery bank (~1400 ah). I’ve noticed that when my Victron MPPT charge controller is on, the victron reads a battery charge of ~13.34 volts. When I turn off the charger, the victron measures the batteries at 12.88v. My coach’s electrical panel shows a voltage of 12.8v whether the charger is on or not.

When I charge my batteries off of 50a shore power, they charge to ~13.2 volts.

should my batteries be charging to north of 13v from the solar panels / charger?

Should I adjust some settings on thr MPPT controller?

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MPPT SmartSolarmppt charging
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1 Answer
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Kevin Windrem answered ·

A charging source may read slightly higher than the battery itself due to voltage drop in the wires between them. However, you are reporting over a 0.5 volts of drop at under 4 amps. That's a bit over 1/10 of an ohm.

Check the wiring between the MPPT output and the battery for a wire size that's too small, very long or other reasons there might be that much resistance.

Keep the wire length between the MPPT and battery to a minimum.

If all else fails, install a battery monitor. The MPPT will then use that voltage rather than it's output voltage for controlling the charging profile.

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Related Resources

Additional resources still need to be added for this topic

MPPT product page

VictronConnect manual

PWM or MPPT

MPPT calculator

MPPT codes